All language subtitles for [English (auto-generated)] Python In-Depth Tutorial 2022 _ Python Tutorial For Beginners _ Python Programming _ Simplilearn [DownSub.com]

hi everyone welcome to the simplyland

youtube channel this session will be

about python for beginners before we

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we from simplyland bring you this

beautifully designed organized and

upgraded python full course for

beginners for 2022.

now let's get started with today's

agenda first we will start with the

briefing on python programming language

then we will learn to install python on

windows and write our first program in

python after that we will start with

basic concepts that is variables and

data types in python numbers in python

python object types and type conversion

strings in python and operators in

python

now understanding the basic concepts we

will educate ourselves with if

statements in python followed by the

python loops python loop coding

techniques control statements in python

and conditional statements in python

with that we will develop a good hold on

the basic concepts now moving on

we will start with python lists tuples

dictionaries

and list comprehension in python

followed by python functions and lambda

function

further we will have hands-on map filter

and reduce function in python moving on

we will get ourself educated with

classes in python inheritance in python

iterators and generators in python

string formatting in python scopes and

arguments in python oops concepts in

python and operator overloading in

python

finally

we will be encountering some language

building concepts

that is modules in python

packages in python file handling in

python exception handling in python

and our concluding concept that would be

sorting in python what is python

python is a high-level object oriented

programming language developed by guido

van rossum in 1989 and was first

released in 1991.

python is often called a batteries

included language

due to its comprehensive standard

library

a fun fact about python is that the name

python was actually taken from the

popular bbc comedy show of that time

monty python's flying circus

now

let's look at the top features of python

first so python has a simple structure

and a clearly defined syntax this allows

the learners to pick up the language

quickly so it is easy to learn and use

python can run on different operating

systems such as windows linux and mac

making it a portable language it enables

programmers to develop the software for

several competing platforms by writing a

program only once

third python is freely available at the

official website since it is open source

this means that source code is also

available to the public

now python uses an object-oriented

approach that encapsulates code within

objects

python provides a collection of

libraries for various tasks such as

machine learning web development and

data analysis

and finally in python you don't need to

assign the data type of the variable

when you assign some value to the

variable it automatically allocates the

memory to the variable at runtime

now with that

let's move on to the users of python

programming

so python programming language is used

to develop desktop applications and

build web applications too

it is popularly used in the field of

data science machine learning and

artificial intelligence to analyze data

build predictive models and make

business decisions python is also widely

used in game development

now

let's see some of the popular python

frameworks and libraries

python can be used for web development

using frameworks like xango flask

pyramid and cherry pie

now you can build graphical user

interfaces using libraries and

frameworks such as

tkinter or just kinter

you can also use pi gtk by qt or pygs or

python javascript

now python is also used to perform

machine learning tasks using libraries

such as tensorflow pytorch scikit-learn

matplotlib and scipy

you can also perform mathematical

computations using numpy and pandas

now let's look at the best ids that you

can use to write programs in python and

perform specific tasks

so we have jupyter notebook which is

part of the anaconda distribution that

is widely used these days even for our

demo in this video we'll be using

jupyter notebook i'll show you in a

while then we have the visual code

editor from microsoft this is also one

of the preferred

ides by learners and companies

then we also have the popular text

editor called sublime text editor

then we also have pycharm followed by

python idli and spyder as our top ides

now let's look at the top companies that

are using python in our day to day work

so we have google quora facebook even

netflix spotify and instagram now there

are other top product based service

based and startups that also use python

programming

okay

now with this theory let's

move to our jupyter notebook where i'll

show you how to write basic python code

so i have my anaconda distribution of

python already installed and i'm working

on a

windows system so

i'll search here for

jupyter notebook

you can see here i have my jupyter

notebook anaconda 3 installed let me

just open it

now this will open on a web browser

you see here this is my chrome browser

okay

so

here i have some python notebooks

already created

now for our demo let me go ahead and

create a new one

so here i'm going to

click on new

and then i'll select python3

this opens

in a

new tab

and here i can write whatever code i

want

all right

so first

let's

see how you can print a simple

sentence or a text in python

now to print something you can just use

the print function

if i write print

within brackets suppose i want to print

my country that is india

now india is actually

a string so i need to pass in within

double quotes

so this is it if you want to print

something you can just use the print

function and pass within the function

whatever you want to print

and now to run this cell

i just need to

click on this run button or you can hit

shift enter to run this cell

i'll just hit shift enter

you can see it here it has printed

india for me

all right

now let's say

you want to

perform some

simple mathematical calculations that

also you can do it suppose i want to

find the sum of

10

plus

50.

i'll just run this cell you see here

it gives me 60. it's very simple

similarly if you want to find the

product of

let's say three numbers i'll write let's

say 40 multiplied by 2 multiplied by 5

if i run this

you get the result that is 400

which is correct

ok

now to store our

values we can

take the help of a variable

suppose

if i write x

equal to

7

this means that my value 7 is stored in

the variable that is x

you might be aware that in other

programming languages also we have

variables and data types which i am

going to

tell you now

so here i have assigned my value 7 to

the variable x

now let me go ahead and print what is

there in x

if i run this cell

there you go

it gives me 7 which means x holds the

value of 7.

now if you want to check the data type

of x you can use the type function in

python

so if i write

type of x

and if i print it

it will also result

in the type of data that x is holding

you can see here the first print

statement prints the value of x that is

7 and the second print statement gives

me the type or the data type of x which

says it is of class integer or

int cool

now

let me show you how you can use

the input function to take user inputs

suppose

i have a variable x

where i want to store some

numbers

i'm going to use the

int function and inside the in function

i'll give my input function

so when i run it

it will ask the user to input a number

i'll write

enter

number

x

okay

similarly

i'll just copy this

come to the next line

i want to create another variable called

y

which will have another number i will

write enter number

for y

and then

i am going to

print

the addition

so i'll write

addition of

x and

y is

give a colon

and then

i'll pass in the operation within

brackets that is x plus y

okay

so essentially what i am doing here is

i am

assigning the value of

my first number to x then i'm assigning

the value of my second number to y and

then i'm finding the

sum of x and y

let me

show you the result if i hit shift enter

it is asking for the user input because

i had defined my input function

so

it is asking

enter number x let me

give my number as let's say 30

i'll hit enter

again it is asking for my

buy input let's say i'll give

60

and then i'll hit enter

there you go it has written me the

addition of

30 and 60 that is 90. you can see the

message as well addition of x and y is

90.

cool

now

let me show you

how to add two strings

and we'll compare the results when you

add two strings and two numbers so

basically

when you add two strings

it is going to merge both the strings or

concatenate both the strings

the way to do is i'll just copy the

let me copy all the three lines of code

from the top i'll paste it here

now i'm going to remove the

integer function that i had used

the integer function was actually used

to

typecast the

input to integer

but now i am going to take the values

in terms of

text or string

now let's see the difference

if i run this

let's say i'll enter my

number as 10 and then

my second number would be let's say 20

if i add 10 and 20

it is going to merge both the numbers

and return me 1 0 to 0.

so

when you add two strings

it is going to return you

the merged value of both the strings

all right

now let's go ahead and explore some of

the popular data types in python

now i am giving a hashtag and typing

data types this means

anything followed by the hash represents

a comment

so

in other programming languages also we

have comments similarly in python if you

want to write a comment you can give

a hash and

pass in the comment

so first let's see i have a variable

a

which has a value of 7

or let's say 10

now if you were to find

the type of

value that a

variable is holding you can use the type

function if i run this it gives me

integer because 10 is an integer

let's say i want to find

the type of value

minus 7 is

now if i run this again minus 7 is an

integer let's say

i want to know

what 3.5 is actually if i run this it

gives me float because 3.5 has a

floating point or a decimal point

similarly let's see

another example i'll write minus 2.4566

if i run this again this is also a float

value

similarly

now let's write a complex number

which has a real part and an imaginary

part

let's say i write

7

plus

10 j

if i run this there you go this is a

complex number hence it has returned

the value is complex

now

if i just write 10 j let's see what it

represents

again it's a complex value

now let's pass in a boolean value

suppose i write true

now true and false are boolean values

so ideally our python should return

boolean only there you go you can see it

has returned us boolean

now let's move ahead and

explore some of the

popular objects in python so we'll start

with

list

list is one of the popular objects in

python

now to

declare a list i'll

create a variable called let's say l1

i'll give an equal to

and within square brackets i'll pass in

my list

list can hold data of multiple data

types

i'll show you now so john here is a

string

i'll give something like 1 0

2 could be the employee id of john

i'll give

usa let's say the

country to which jon belongs to

and i'll give a floating point value

let's say 180.5

assuming it's centimeters and this is

john's height suppose

if i run this

you see i have created my list and if

you

want to print it i'll just write l1

there you go

so here i have my

list l1 printed

now suppose you want to

check the

type of l1

you can use the type function again and

pass in the

variable that is l1

there you go

it tells that l1

has the values in the form of a list

similarly you can create

list

of the same data type let's say

only of numbers

okay

now if i just print l2 you can see

2 has only numbers

similarly you can check the

type of l2

run this it is also a list

okay

now another popular object in python is

called a tuple or tuple

now the only difference between

a list and a tuple is that lists are

mutable which means once you declare a

list you can change the values

while tuples or tuples are immutable

which means that once you declare a

tuple you cannot change the values

now another difference is that

list is written within square brackets

but when you assign a tuple it is within

normal

braces or round brackets as you say

so i'll create a tuple called tup

and within

brackets

i'll

give the values let's say

i want to give the

values of vehicles or cars

so brands of different car we have in

this tuple let's say bmw then we have

audi

next we have mercedes

let's say

jaguar

okay

now

you can use the print statement to print

the tuple

and let's say i also want to print

the type so i'll use the type function

and pass in my variable that is tup if i

run this

you can see the first print statement

prints the

values present in the tuple top and then

we have the type

you can see it is of type or class tuple

now next we have our

third object

which is called a dictionary

i am giving comment here for readability

okay

now dictionary consists of key value

pairs and

again mutable objects just like list

which means you can change the values of

the dictionary once they are assigned

and dictionaries are written within

curly braces

let's say i want to create an employee

dictionary

so i'll give my variable name as

employee

and then

start with my

curly braces

first

i'll give the key

say

the name and then we have the

name of the person in terms of value

that is john

next we have his age

let's say ages 29

now one thing to remember here is the

keys should be passed within double

quotes

and the value is a string you can pass

within quotes

but if the value is an integer or a

floating point

number you don't have to pass within

quotes

let's say i want to have the

salary of john as well

again salary is in terms of numbers so

you don't have to pass it within

quotes

let's say

the third information or the fourth

information i have about

john is the company in which he works

let's say

john

works at oracle

so i have my dictionary defined

now

i'll write print

my dictionary employee

and then

i also want to check the

type

okay

let's print

there you go so the first print

statement prints the dictionary employee

and then we have the

data type of

my dictionary employee that is dict

which means dictionary or dict

the fourth python object we are going to

discuss is called a set

now even

a set is created using curly braces like

how we have used in the dictionary but

the difference is sets do not contain

key value pairs

but

they can only contain unique values now

let me show you what i mean

let's say i want to create a set

that has only unique values of months so

within

curly braces i'll pass in my

month names let's say jan

then i have

feb

then i have mar for march

let's say apr for april

so this is a set

and if i want to print i can just

pass in the

variable name that is month let's run it

okay you can see it here it has printed

my set which is not in an order

okay

now you can also check the

type of the variable that is month

if i run it you can see it here it is of

type

or class set

now the difference i want to show here

is as i mentioned

set can only contain unique values

suppose i have another value of

month let's say february feb

if i run this

i'll remove this

if i run it you can see here

still

my set has only unique values so it does

not consider any duplicate values

all right

now moving ahead we will explore how to

extract certain values from the

python objects we'll be using different

techniques bait indexing or slicing

okay

so if i go to the top i had created a

list called

l1

let me print l1 again

okay so these are the values that i have

in my list

l1

now let's

say i want to print

the first element

in my list l1

the way to do is i'll use my print

statement

i'll give my variable name that is l1

and within square brackets i'll give the

index

let's say one

if i run it

it gives me the value 102 the reason

being

in python the index values start from

zero

so this the first value is at index zero

then the second value is at index one

the third value is at index two and the

fourth value is at index three

so if you have to

find what is there at index

3

i just need to replace

1 with 3.

if i run this

you see it here it gives me

180.5

which we had assumed to be the height of

john in centimeters

now you can also do this without even

using the print statement that is the

beauty of python

if i write l1 and within

square brackets let's say i write

2 if i run this

it gives me usa because

usa is the value that is present at

index 0. so

very important thing to remember while

indexing or slicing

is that the index values start from 0

and not 1. so if you had to find the

value

where john is present

you need to use

0 instead of 1. if i run this it will

return me john

ok

now you can also use negative indexing

let's say i write

l1

-1

you can take a guess

what this will return

if i run this

it returns me 180.5

when you use negative indexing

it will start from the

last position so minus 1

is actually this index

let's say i'll write minus 3

and see the result it gives me 102 which

is fair enough if you start from

the back this is minus 1 usa is at minus

2 and at minus 3 we have 1 0 2

all right

also you can use slicing

let's say i'll write l1

within square brackets i'll give let's

say

from 1

to

3

so i want

all the values present from the first

index which is this

till

the third index but

excluding the third index

if i run this it gives me

102 which is at the first index and then

usa which is at the second index now in

python

the

last index is exclusive it is not

included so in case you wanted to print

180.5 as well we have to change this

from three to four

now if i run this

you get

180.5 as well

okay

moving ahead

there are some basic

functions that you can use

with python objects for example if you

want to

add any

value to your list l1 you can use the

append function

suppose i write l1

dot

append

let's say i want to add the

vehicle or the car

that john has

let's see i'll write append

range rover

if i run this

and let's print l1 again

you can see it here we have appended or

added a new value to our list l1

cool

now you can also use the reverse

function

in python if you want to print the list

in reverse order

so let's see

i want to print the elements present in

l1 in reverse order

i just need to write my variable that is

l1

followed by dot and the reverse function

it's very simple

if i run this

and i will print l1 now

it prints my list in reverse order here

it was from

john all the way till range rover

once i reverse it it starts from range

rover and all the way to john

cool

similarly

you can

also

extract specific values from tuples and

dictionaries let me show you

i'll just go to the top and

okay so we had created a tuple called

tup

let me print that tuple again

so these are the values of the different

brand of cars we have in the tuple

let's say

you want to find

the car that is present in the second

index so you can just write

2 within square brackets

so i have my double name followed by the

square brackets and then i have my index

if i run this you get more cities and

again

in python tuples the index values start

at zero and not one so bmw is at index

zero audi is at index one mercedes is at

index two you see it here and then

jaguar we have it index three

again you can use slicing by using colon

and you can also use

negative indexing let's say i'll change

the value from

2 to let's say -3

see the result you see here we have audi

because this is minus one

mercedes is at minus two and aud is at

minus three

okay

now

you can extract the values in the

dictionary

by using the keys in the dictionary

let me go to the top and

see the dictionary that we had created

it is employee let me print it

now in jupyter notebook you can also use

the tab to auto complete a variable name

or a function name

is one of the features that jupiter

notebook provides

so here we have the employee

dictionary

and let's say

you want to

print

the value

of salary

the way to do is

i'll write print

employee

dot i can use the get function

and within the get function

i'll pass in my

key for

salary

if i run this you see here it gives me

2 lakhs 50 000 which is the salary of

john

similarly if you want to let's say

update any value in the dictionary you

can use the update function

suppose

i want to update

the company of john

from oracle to let's say

google

the way to do is

i'll write

my dictionary name that is employee

followed by the update function

and then within curly braces

i'll pass in

my key that is company

give a colon

and change it to

let's say google

now

i can just

print my

employee dictionary

there you go

so from company oracle we have changed

it to google now

so these are some of the very

crucial features or important features

that are available in python which helps

you do

a lot of calculations and data

manipulations

all right

next

let's see how to use

an if else

condition or any file statement in

python

like in any other programming languages

be it c c plus plus or java you have if

else statements

in python also we have a full statements

so basically you check some condition

and return a value

suppose i have a variable called a which

has a value of let's say 400

and then i have a

variable called b which has a value of

250 okay

now

i'll use if condition i'll write if

b

is

greater than a

then

print

b

is

greater

now you will

also have an else statement i'll write

alif which means else

if

a is equal to equal to b

colon then

print

a and b are equal

finally i'll write my else statement

else

print

a

is

greater

so what i am doing here is i have

assigned two variables a and b to value

400 and 250 respectively then i am

writing an if else condition so i am

checking a condition

if b is greater than a which means i am

comparing if 250 is greater than 400 in

case it is true then print b is greater

else if

both the values if they are same then

print a and b are equal

otherwise print a is greater

let's run it and see the result

this is fair enough

it prints me a is greater because

b is not greater than a so 250 is

definitely not greater than 400

so this

condition fails even the alif condition

fails only the final condition else is

true that is a is greater than b

so this is a simple example

of using the files

condition of the file statement in

python

now moving ahead

let's see how to use a while loop in

python

now using the while loop you can execute

a set of statements as long as a

condition is true

let me show you a very simple example

i'll write

i equal to 0 so i've assigned value of 0

to i

then i'll write while

i

is less than

8

then

i am going

to

add

i so i'll write i equal to

i plus 1

i'll use another condition if

i

equal to equal to

4

give a colon

and then i am going to use a statement

called continue

i'll print i

so

using the continue statement you can

stop the current iteration and continue

with the next iteration

let's print the result and see

okay

so here

we are checking if i is less than 8 so

first value is 0 0 is less than 8 then i

am incrementing the value of i to 1 so i

becomes

1 now so from 0 it becomes 1

then i am printing i

this condition continues

until we have the value of i equal to 4

so if the value of i is equal to 4 i am

skipping the current iteration so if you

notice the result after 3 we have 5 so

we have skipped

printing 4 and

gone to the next value of i which is 5

so the loop runs till this condition

fails

so

when i is

not less than 8

the loop terminates

all right

finally in our demo let's see how a for

loop works so a for loop is used for

iterating over a sequence that is either

a list a tuple a dictionary a set or a

string

so let me go ahead and create my tuple

tup

equal to

let's say i have

the same brand of cars we have bmw

then i have audi

let's see i have

more cities

i have

jaguar

and then

i have bmw again

all right

i'm going to print

the values present in the tuple one by

one so for that i'm going to use a for

loop so i'll write for

a variable x

in

my tuple

i'll say

print x

so what it will do is

this randomly assigned variable x will

iterate through all the elements in the

tuple and print them one by one

let's hit

shift enter to run it there you go you

can see here i have all the

different

car brands printed one by one

cool

so this brings us to the end of our demo

session on introduction to python let me

go to the top and tell you what we did

so first i told you how to print any

set of statements or any string text

numbers in python you just use the print

statement or the print function

you can also perform very

simple mathematical calculations using

python

then you can also check the data type of

the variable using the type function

then we saw how to use the input

function here we inputted an integer and

then we found the sum of both the

integers x and y the value was 90.

in the next example we removed the

integer function by considering our

values as strings and then we saw the

difference in the results so when you

use strings

the addition operation will concatenate

or merge both the strings or the numbers

then we saw the different data types we

saw

about integer data types about floating

data types boolean data types

if i scroll down we saw

the important

python objects like list

then we had

tuple then we saw how to write a

dictionary how to create a set then we

saw the difference between

list and tuples and even

how set can take only

unique values

then we used some

indexing operations to extract specific

values from lists tuples dictionaries

we also

learned some of the important functions

these are all inbuilt functions that

python gives us

to perform manipulations and operations

in python

so you used append then we saw how to

use reverse

now let me just go ahead and show you

another

function an inbuilt function in python

i'll just insert a

cell below this

suppose you want to find the length of

your list

you can use the length function or len

function that is

inbuilt in python i'll just pass in

ln followed by

my

list that is l1

if i run this

it gives me the result 5 because you can

see it here

my list has 5 elements in it you can

count it so the length becomes 5.

similarly you can also

check the

length of the tuple

let me insert a cell here as well

suppose i write lin

of my tuple that is tup if i run it

again

it says 5

now this was the earlier tuple that we

had created

later we actually created

another tuple

let me show you

okay so this was the tuple it has

taken this new tuple which has five

values in it so the length becomes five

let me go to the top

okay and after that we learned how to

use if else

followed by how to write a while loop

and then finally we saw how to

use a for loop in python

in this session we will learn how to

install python and install numpy scipy

matplotlib and pandas libraries then we

will install the anaconda distribution

in our system

so let's start

as you all know python is an interpreted

language so you need to install a python

interpreter so for that we will go to

the browser

and search for python dot org

now we will move to the downloads page

and choose the latest version of python

to download and the latest version is

python 3.9.5

we'll click on the download

once the installer has downloaded open

it

now you can see the installation window

for python

you have to double check both the boxes

add python 3.9 to path

and click on install now

as the installation completes you can

see a screen that says the setup was

successful now click on close

now to check whether the python has been

installed successfully on the system or

not we will run a command on the command

prompt let's open the command prompt

click on start

and write cmd

now to check whether the python is

installed or not we will run the command

python minus minus version

python space minus minus

version

and press enter so here we can see that

python 3.9.5 version is installed in the

system so yeah python is working in the

system now we'll run some commands for

python

so for that first we will type py

and press enter

and now we will write the basic command

that is

print

bracket

hello world

semicolon and press enter

as you can see hello world is printed

here so yeah python has started working

in our system

now we will install libraries of python

we will be using pip to install numpy

sci-fi matplotlib and pandas library and

before installing the libraries make

sure the latest version of pip is

installed in your system so to check

that we will run a command in command

prompt

we will open the command prompt

and write a command

pip space minus minus version

and press enter

as you can see the pip version is

21.1.1 and it's being downloaded with

the python 3.9 so it's the latest

version we have downloaded

so now

we have to keep one thing in mind before

installing scipy matte protlib and

pandas library first we need to install

numpy library

so for that we will run a command

pip

space

install

numpy

and press enter

depending on your internet speed it will

get installed

as you can see the numpy library has

been installed and there's a warning

that our pip version is 21.1.1

and we should upgrade it to 21.1.2

that is the latest version available so

we'll upgrade the pip version for that

we will write a command

python

space minus m space

pip space

install space minus

upgrade space

pip

enter

okay so we made a mistake here in the

command so the mistake is we have

written only one minus sign before the

upgrade we have to write two minus signs

before the upgrade

so we'll write the command again

python

space minus m

space

pip space

install space minus minus upgrade

space

pip and then press enter

and now depending on your internet speed

the pip version the latest version will

be installed on your system

as you can see they have uninstalled the

pep version 21.1 and they have installed

the latest version that is 21.1.2

we have installed the first library that

is numpy and that's the basic

requirement

for the installation of scipy library so

now we will install the scifi library

so for that we will write the command

pip install scipy

pip space

install

space sci-fi and press enter

and depending on your internet speed it

will be downloaded

now you can see that the scipy library

has been installed successfully and here

you can see

that the requirement already satisfied

numpy so we have firstly downloaded the

numpy library so that we can easily run

the scipy library

now we will download and install pandas

library for that we will write the

command

pip space install

pandas

and press enter

and this will also

install depending on your internet speed

we can see that the pandas library has

been successfully installed now we are

left with matplot lib library so now we

will install that for that we will write

the command

pip space

install

mat

load lift and press enter

as we can see the matplotlib library has

been successfully installed

now we have installed all the four

libraries

so if you want to check whether the

library is installed on your system or

not

you can write a command to check that

first you have to write python and press

enter

first we will check for numpy library

and for that we will create a array

for that we will write the command

import

numpy

s and p and press enter

if you don't get any error it means that

the library has been installed

successfully so now we will create an

array

a equal to

np dot

array

1 comma 2 comma 4

comma

5 comma 7 comma

9

comma

d type

equal to

we'll set it for float

press enter and we want to print this

array

like print

array

created

a

and press enter

you can see the output error created one

two four

and five seven nine

so the numpy library is working fine

so we will check for other libraries for

that

we will write

import

space

mat port live

and press enter

if you don't get any error it means that

the library has been installed

successfully

so for the rest also we can

write the same commands import

pandas and press enter

we do not get any error so the library

has been installed successfully and we

are left with sci-fi so we'll write

import

space sci-fi and press enter

so here also we didn't get any error so

the library has also been installed

successfully

now we will see what anaconda is

anagona is a free and open source

distribution of python and our language

here we have conda which is a package

manager system similar to papen python

so now we will see how to download

anaconda and then we will explore its

features

to download anaconda first we will open

the browser

and search for the keyword anaconda

we have to visit the official website

that is www.anaconda.com

and now we will click on the products

section and choose the individual

edition as it is open source edition and

it is free of post

now we will scroll down

here is the toolkit for the individual

edition and will click on the download

on clicking the download we are directed

to the bottom of the web page and here

we can see the different versions

available for windows that is 32 bit and

64 bit

we will download the 64 bit and it is of

size 477 mb so it will take ample amount

of time to download

we will download it

as the download completes click on the

application file

now click on next

the license agreement will appear

now click on i agree

then you have to select the installation

type

if you want to install for a single user

click on just me

i'll select for all users and click on

next i am installing for me

so i'll click

next

then it will ask for installation

location

after selecting location click on the

next

my for me the location is fine so i will

click next

then advanced installation options will

appear if you have already installed

python on your system as we have

installed already so we do not have to

click on this section

we will only click on this section and

press install

it will take time to install

after the installation is complete click

on next

then click on next

and uncheck both these options

and click on finish

as you can see the installation has been

completed

now

we'll go to start and type anaconda

we can see that

anaconda prompt and anaconda navigator

are visible

first we will open anaconda navigator

it's initializing and adding features

here you can see some pre-installed

applications

and tools that are already installed in

the anaconda

and if you want to install any other

tool you can

like you can install our studio python

professional orange 3 blue is

in the anaconda

and you already have spider qd console

powershell prompt jupiter notebook

jupyter lab ibm watson studio cloud

datalore cmd.exe prompt

so now we will open an upunder prompt

now let's see which version of conda is

installed in the system for that we'll

write a command conda space info

and press enter

here we can see that the corner version

is 4.10.1

now we will launch jupyter notebook for

that we will write the command

jupyter notebook

and press enter

you can see that the jupiter notebook

has initiated

now create a folder where you want to

store the projects and rename

accordingly

so to create folder

will create the folder in onedrive

sorry

i will create the folder on desktop

new

folder

we will click the untitled folder

and rename it

and rename it as

python

1

now minimize the window

and

open the desktop

you can see that the python one

directory is created

and now we will click on the python one

folder

and create a python 3 notebook

as we have created a python 3 file in

the jupyter notebook now we can run the

python commands on it so we will run

some commands

and first we will run a basic command

that would be print

print

india

and we will run this command media is

printed here

i'm going to run some

operators

like we will

print

7

into eight

and

the run so it's 56

and we'll also run an exponential

operator

print

to 6.4

so you can see

16 the result comes out

so now to save this file first we'll

rename it

demo one

rename

and we will save it

save and checkpoint

now you can check in the directory you

have created python one

that it is being saved as demo1 in this

session we will learn to write a program

in python ideally then we will see a

program to add two numbers and

afterwards we will run a program in

jupyter notebook

as you all know python is an interpreted

language so we require a python

interpreter to work upon while

installing python in our system we also

get python idi automatically installed

but before writing a program in python

ideally we will write a program on

command prompt

so for that first we will open command

prompt

we will click on start and write cmd

and click enter

now the command prompt appears

first we will check the python version

pip space minus minus version

and press enter

you will see the python version 3.9

now

we will start writing the python program

for that first we have to write the

command p y and press enter now we can

start writing our program

we will write a basic program on

division

for that we will assign a value

5

to a variable a

and

value 10 to the variable b

and we will divide b

by a

and we'll print the value

of c

press enter

as you can see we have got an output 2.0

now we have run a program on command

prompt successfully now i will write a

program in python ideally

so to write a program in python idli we

will see some steps

first we have to open the python ideally

then click on file menu and choose the

new file

and

after writing the program we have to

save the program with dot py extension

and then we can click on the run menu

and then we will see a run module and we

have to click on that

now we'll see it practically for that we

will click on start

and search for id ali

and now we'll click on python ideally

now we will follow the steps as we have

seen now

we will click on file menu and choose

new file a new window will appear

here we will type the program to get two

numbers inserted by user and add them

but before writing this program let's

understand this program

so python program on adding two numbers

first we have to get an int value

inserted in variable a for that we will

write the command a equal to

int

round brackets input round bracket

started for the message we have to put

it in inverted commas and the first

number colon round bracket close and

another round bracket close

now we will insert an end value in

variable b

for that we will write the command b

equal to int round bracket started input

around bracket started for the message

we will put the message in inverted

commas and the second number colon

and then we will close this message

by round bracket and another round

bracket closing

then we will assign a variable c

and add the operation a plus b for that

now we'll print

a message that would be addition of two

numbers equal to that would be an

inverted commas

comma c

as c variable will store the result of a

plus b

all the statements in the program will

get executed line mainly now we will

execute this program on python ideally

so for that we will write our program

here

that would be a equal to

and

round bracket start

input

round bracket

inverted commas

enter first number

invited commas close

round bracket close

be equal to

end

input

round bracket started inverted commas

for message

enter second number

inverted commas

round bracket close

now we will assign the operation a plus

b in variable c for that we will write c

equal to a plus b

and now we will print c

before executing this program we will

save this program file

save as

we will save it as demo1

and we will write the extension py

and press save

as the program is saved now we will run

this program by click on this run menu

and then click on run module

you can see the program has been

executed now we will write the first

number that would be 10

press enter and second number will write

6 and press enter we will get 16 as an

output

so we have executed the program on

python ideally

now we will see some best python ids

in the market

for that

the best python ids in the market are

jupiter notebook visual studio code

sublime text pycharm

python ideally and spider notebook among

all these ids we have worked with python

ideally now we will write a program in

jupyter notebook

for that you have to install jopeta

notebook

i have installed anaconda distribution

and it has python id already installed

if you want to know how to install

anaconda distribution go and check the

video in python playlist

so let's open jupiter notebook for that

first we'll click on start

and write

jupyter notebook

and click on the jupyter notebook

anaconda 3

and we will wait to get it started in a

browser

now we'll select the location where we

want to store the program

we will select the location in onedrive

desktop

and i've created a python 1 folder there

so here we'll create a new python 3

notebook

and

name it as

first python

program

and now here we can start writing a

program

here we will write a program to multiply

three numbers

so for that we will get all the three

integers inserted by the users in three

variables and then we will operate the

operation multiplication

so for that we will write the command a

equal to end round bracket started

input

round bracket and here we will print the

message

enter

first number

colon

and then

noted commas clause and the round

bracket clause now we will enter

another integer in variable b

for that we will write the command equal

to end round bracket

input

round bracket started inverted commas

enter second number

colon

and then we will close the inverted

commas and the round brackets

and now we will get the third integer

inputted by the user in variable c for

that we'll write the command c equal to

in

round brackets input round brackets

inverted commas

enter

third number

colon

inverted commas close and round bracket

close now we will assign the operation

of multiplication in variable d

that would be by the command d equal to

a

into

b

into c

now we'll print the variable d

and for that we will also print the

message

multiplication

of three numbers

and close the inverted commas and then

we will

insert a comma and then write the

variable d

as d contains the output of a into b

into c now we'll click on the run

command

and now we will enter our first number

that would be

five

and press enter then the second number

four

then the third number six and then press

enter

and then we will get the output of

multiplication of three numbers as 120.

now we have successfully run the program

on jupyter notebook so in this video

we will learn what is a variable in

python

then

we'll understand what are object

references

we'll also see the different rules for

python variables and finally

we'll understand variables in detail

with hands-on demonstration on the

jupyter notebook

so variables in python hold an object of

a particular data type python variables

are containers for storing data values

we do not need to declare variables

before using them or declare that data

type like we do in other programming

languages such as java or c plus plus

python is not statically typed

a variable is created the moment we

assign a value to it

a variable is a name given to a memory

location

so here we can see

we have a variable called car and it has

a value called bmw now this value is of

type string since it is written within

double quotes

variables can have values of multiple

data types

now python also allows you to assign

values to multiple variables in one line

so here you can see i have assigned

x y z to audi bmw and mercedes in one

single line

all right

now let's look at object references in

python a python variable is a symbolic

name that is a reference or pointer to

an object

once an object is assigned to a variable

you can refer to the object by that name

so here we are assigning an integer

value of 50 to the variable a

so assignment creates an integer object

with a value of 50 and assigns the

variable a to point to that object as

you can see here so a is the variable

and it is pointing to the object that

has 50 value

now let's see another example so in this

case

we have

assigned

a variable a which has a value of 50 and

then we have created another variable

called b

that has the value stored in a

now python does not create another

object in this case

it creates a new symbolic name or

reference called b

which points to the same object that a

points to

so here you can see

both a and b

are pointing to the same object that is

50.

okay

now

in this example

python creates a new integer object with

a value of 100 and b becomes a reference

to it we will explore all of these in

our demo

now

there are some rules for python

variables

let me just

read all the

and we will explore all these rules in

our demo session

so first a variable name

must start with the letter or the

underscore character

a variable name cannot start with a

number a variable name can contain only

alphanumeric characters or underscores

so you can see from a to z 0 to 9 or

just underscore

variable names are case sensitive so

here you can see i have written

date

in three different types and

these

are read as different variables and not

the same variable

and then

there are several techniques to write

multi-word variables you have the camel

case you have the pascal case and we

have the snake case don't worry about it

we'll explore these

in the demo

now let me take you to my jupyter

notebook where we will understand

variables in detail

okay so i am on my jupyter notebook and

i have

my title as variables in python

so let's start

with my first variable let's say i have

a variable called a and i am assigning

50 to it

now you must be aware 50 is of type

integer

so

this a variable is now

holding an integer value

now if you want you can just print a

if i hit shift enter

it will give me the value of 50.

now to check

the data type of a you can use the type

function now we have covered data types

in detail in our previous video if you

want you can have a look at it

so i will write type of a if i hit shift

enter it gives me the integer type

okay

now

let me show you another function called

id if i write id of a

let's run it it gives me a number this

is a long number

now the id function in python returns a

unique id for the specified object so

here object is a

so all objects in python have its own

unique id

the id is assigned to the object when it

is created

now what if

i assign

100 to a this time and let's see

the id of a

if i run it you can see here the values

are different than the previous one

so every time the id function will

return a unique id for the specified

object

all right

now

we learned in our theory section that

you can assign multiple variables in a

single line now let me show you how to

do it

suppose

i'll write x

comma y comma

c

so these are the three variables

and i want to assign

three values to them

so let's say x will have 50

in y i want to store let's say

168.6

and

my z

will have

a string or a text value let's say

simply loan

all right

let's run it

okay

now you can

print them one by one

you can see here x has 50

y has

168.6

and z has

simply learn of type

text you can check the

data types if you want let's say i want

to check the data type of y

it gives me a float because 68.6 is a

float

you can check the data type of

z

it is of type string

okay

now you can also perform the same

operation of assigning

multiple variables in a single line in

another way let me show you how to do it

suppose i want to assign

the same

value to three different variables let's

say i want to assign the value of 10 to

x y and z

so i'll write

x equal to y equal to z equal to

i'll write 10.

if i run it

and let me print them one by one you can

see here x is 10 y is 10 and

z is also 10.

now there is

another way to do it that is

i'll pass in my variables x comma y

comma z

and then

i can write 10 comma 10 comma 10

this will return the same result

okay

now let's look at the

rules for writing variable names

so these rules we had discussed in the

pbt section

now we'll explore them one by one so the

first rule is a variable name

must start with a letter or the

underscore character

so

let me just give a comment first

rules

for variable

naming

so the first rule says a variable name

must start with a letter or the

underscore character so if i write let's

say

some random variable name abc equal to

100

this is

valid you can print it

abc it gives me 100.

now

you can also write the variable name as

a

followed by any number

it should be integer number

if i write 102 equal to

let's say

this time

i'll

give a string let's say

india and let me print it

it works perfectly fine

now we also said the name must start

with an underscore

i can start with an underscore and then

write let's say 123

is equal to 70.5

now let me print it

now this works as well so you can start

your variable name with an underscore

followed by a letter or numbers

let me show you another example this

time i follow the underscore with

letters let's say

dog

i'll just give

any random dog name let's say i have a

dog called puppy

and let's see i'll print it

this also works

okay

now

you can have multiple underscores in

your name as well

suppose i'll write

underscore

name

underscore each

this is my variable name

i'll write

let's say

stuart

36

and let me print it

i'll write underscore name underscore

age

this is also a

valid variable name so you can have

multiple underscores in your variable

name

now

the next rule is a variable name cannot

start with a number

so if i write

let's say 4

name equal to

gilly

and if i try to print it

it will throw an error so you cannot

have a variable name starting with a

number

all right

now

let me

scroll down

the next rule is a variable name can

only contain alphanumeric characters and

underscores

so if i write at the rate

then let's say

age

equal to

40 if i run this

it throws me an error because at the

rate is not recognized and it is not

a valid variable name

similarly let's say i'll write

name

dollar

age

equal to let's say 40

again this is not recognized dollar you

cannot use it in your variable name

the next rule is

variable names are case sensitive

so suppose i have a variable called car

which is all in lower case

and

my car has a value let's say bmw

now if i were to print car it gives me

bmw

suppose i have another variable which

starts with a capital letter

c followed by lowercase ar

if i were to assign

car to let's say tata

and i print it

it returns me tata and not bmw so you

should keep in mind that variable names

are case sensitive

now similarly i can also have a variable

in all upper case let's say

my

car is of toyota brand

i made a spelling mistake

okay now if i print car

it gives me toyota

so

these are the different

types of using case sensitive variables

now another important

thing to note is

in python reserve words cannot be used

as a variable name

so let me open a new tab and here you

will search for

reserve

keywords

in python

let me open this link

or any other link for your reference

you see here

these are all

your keywords in python and these cannot

be used as variable names let's try

using a few of them let's say i'll use

break

let's assign

a value to variable break equal to let's

say

60 if i run it it gives me an error

invalid syntax break you can't use

similarly let's use

another keyword let's say i'll use for

this time

we have a keyword

called for you can see it here

suppose i write

for

equal to

i have

let's say virat

if i run this it throws me an error

again

let's try one more keyword

do we have try as a keyword yes we have

you can see here try is a keyword

if i write try equal to

any random value i'll pick this time i'm

giving a floating number let's say 140.5

if i run it again it throws me a

error

but

you can use

an underscore and then

you can give that keyboard let's a try

i'll assign the same value

and let's say we'll print it this will

work fine since

the variable name is no more a keyword

because we have an underscore

in the beginning

ok

now let me show you some

basic operations that you can perform

on python variables let's say we have

a equal to 100 and let's say b equal to

200

you can assign

an operation to another variable called

result let's say i want

the operation to be an addition

operation

and let's

go ahead and print result

you can see it has given us 300 because

in result we are storing

the addition of a and b so 100 plus 200

is 300

now similarly

you can perform

many operations like let's say this time

we'll perform a subtraction operation

so this time i'm storing

a minus b in result and let's go ahead

and print result you can see here 100

minus 200 is minus 100

then you can also have

let's say result equal to

a

by

b

and let's print it

fair enough we have 0.5 because 100

divided by 200 is 0.5 similarly you can

also have

integer division suppose i write 100

divided by

say 40

and i'll

print the result

you see here it has given us 2.5 but

what if i want to perform an integer

division so i'll add

one more forward slash here and let's

run it it gives me only two so it has

truncated the 0.5

okay

now moving ahead

let's say i have a variable called

country

and

i have

india in it

so country is my

variable name and it is pointing to the

object that has

india as the value

i can print the

variable

you see here i have india

and now if you want you can perform some

extraction operation

suppose if i write country

within square brackets if i write

3

it gives me

the character that is present at the

third index so i is present at the 0th

index n is at the first index d is at

the second index and i is at the third

index let's say i want everything that

is present

until the third index it gives me ind

so this 3 is exclusive it will only

return us

the values present at the zeroth index

the first index and the second index

okay

now let me show you another interesting

example

suppose i have a list that is called

cars

and i have a list of

car names

let's say i have

bmw

then i have

ferrari

and let's say

i have toyota

i'll run it and i'll print my

list that is cars you can see here

there are three car names

and now what if i want to

put each of these car names in different

variables so i can write x comma y

comma z

and

i'll write equal to cars

if i run this

now what it will do is it will assign

each of these values to

x y and z respectively now if you want

to print x you can see here

x has bmw then y has ferrari and z has

toyota

so this is another way to assign

values to variables

from a list

okay

now

you can also

use variables in the print

function or the print statement suppose

i write x

equal to let's say it has simply learned

now

i can print a message let's say

welcome

to

i'll give a space

close the quotations

give a plus sign and i'll give the

variable name

if i

run it you can see here

the message is printed welcome to

and the x which has the value of simply

loan so welcome to simply loan okay

now another thing to note in python is

that you cannot add an integer and a

string suppose i have x as the variable

and it has a value let's say 20

and then

i have y which has

the string simply learn

now string can be put in double quotes

or in single quotes you can use

whichever way you want

suppose i print

x

plus y

let's see the result

it gives us an error so you cannot

print

or add

an integer and a string so you need to

convert one of these

values

now there are several techniques to

write multi-words variables

you can use the camel keys to write

multi-word variables

so here each word except the first

starts with a capital letter

so i'll just give a comment here and

write

camel case

and

the way to write is

apart from the

first word

all the words

start with the capital letter

suppose i write my department equal to

marketing

so here

the first word my

the m starts with a small letter while

the second word department the d starts

in a capital letter so this is an

example of a camel case

if i

want to print it i can write my

department

and run it it gives me marketing

let's see another example

i have let's say car brand

so you see here

car brand are two words

but

the first word starts with a

small letter while the second word has

an uppercase

b

let's say my car brand is hyundai

now you can print it

there you go all right

moving ahead

we also have

pascal case where each word starts with

a capital letter

suppose

i have a variable called my name

is

let's say nathan

here you can see my and name are two

different words and

both the words start with a capital

letter so this is an example of pascal

keys

if i run it

let me just print it first okay you see

here i have my name similarly let's say

we have another pascal case

multi-word variable which is age now

where

age has a caps and now

has n caps so this is also an example

of a pascal case variable let's say my

age now equal to 30

i'll print each now

it returns me

30.

now one thing to note here is if i write

let's say age now

if i do this it gives me an error

because your variables names are case

sensitive so we haven't created any

variable which

has small a and small n in each now

okay

now

the third way to write a multi-word

variable is called as snake case

so

if you want i can

give a comment

saying snake case

so here each word is separated by an

underscore character

so let's say i have a multi-word

variable which is city underscore

address

and let's say the city is

new york

now if i print it

you have new york so this is an example

of a sneak case where

each word has a

underscore in between you can have

multiple underscore between each word

suppose i write my

current

age

equal to 35 let's say

so i have

my current each

i run it

okay there is some mistake here i have

missed an r

you see here it says 35 so this is also

an example of a snake case where each

word is separated by an underscore so

here we have two underscores

all right now let me go to the top and

let me brief you what we did so first we

saw an

integer

value variable

we saw how you can check the

data type of the variable using the type

function then we explored about the id

function

we saw how you can

pass in

variables or multiple variables in a

single line

then

we saw how you can assign the same value

to three variables in one line

now this is another method to do the

same operation

now

then we looked at the

different rules for naming variables

your variables can start only with a

letter or an underscore

and that letter can be followed up with

numbers as well and you can have

similarly numbers after

underscore you can also have characters

after underscore

you can have multiple underscores

but your variable name cannot start with

a number

and it cannot have special characters

like

at the rate or

dollar symbol

these will throw an error

now you can see

your variable names are case sensitives

so here we defined car in three

different ways

and all the three

give us different results

another important thing we saw was

you cannot use

keywords python keywords as variable

names we saw break for and try

now we perform some

basic mathematical operations we also

saw how

you can perform some extraction

operation using string values in python

then we saw another way to

assign the values of a list to different

variables

we saw how you can use the variable name

in a print statement

then we saw how

you cannot add an integer

with a string

we explored the camel case

then we saw

how you can

write multi-word variable using pascal

case and finally we looked at

snake keys

so in python

every value

has a certain data type

the variables in python hold an object

of a particular data type

since everything is an object in python

data types are actually classes and

variables and instances of these classes

now there are various data types in

python

first we have the numeric types which

are essentially numbers so under numeric

types we have integers floating point

numbers and complex numbers

then we have x type data which are in

the form of strings

the third type of data that is available

in python are called as sequence types

which consists of less tuples and range

we have already seen about lists and

tuples in our previous video

and in python we also have dictionary

objects as mapping data types

in the previous video you saw how to map

key value pairs using dictionaries

next

we have set data type now sets are

unordered collection of unique items

python also supports boolean data types

and finally we have

binary types of data which include bytes

byte array and memory view

now let's head over to the jupyter

notebook where we will learn about these

data types in detail

so here i am on my jupyter notebook and

i have titled my notebook as data types

in python rec is for recording

so let's first start with numeric data

types

i'll give a comment using

a hash tag

i'll write

numeric

data type

okay

let me define a variable called num

in which i'll store a value of seven

now let me go ahead and print

the data type of

my variable num so for that i am using

my

function as type

if i

run this using shift plus enter you can

see here it tells me that

num variable is holding a value of type

integer

now you can also

use a print statement

i can write something like print

num

comma

i can give a message as ease of

type

i'll give another comma and then i'll

use my function type of

num

let's see the output

you can see it here

it

first

gets the value that is stored in the

variable num so 7

is of type and then it prints the

classes of type class integer

all right

i've just increased my

size of the notebook

next

let's declare

the same variable num and this time

we'll store the value as let's say 10.8

now you can see here there's a point

which means

this is a decimal

or a floating value if you can check the

type of num it gives us

num is holding a value of type float

now let's say

i'll take a negative number let's say

minus 10.8 and we'll see the type of

num

again minus 10.8 is also of type float

now let's say i'll declare

a complex variable let's say

8

plus

6

j

now this is

a complex number

which is again of type

numeric data type

if i want to check the

data type of num it gives me complex

because 8 plus 6 j is of

complex data type

okay

now if you want to extract the

real and the imaginary

parts of a complex number you can do it

something like this

you need to pass in the variable name

followed by a dot

and

the attribute name

is real to extract the

real part of the complex number if i run

this you can see here it has returned

the real part of the complex number

which is 8. now if you want to print the

imaginary part you can use num dot

imeg which is for imaginary if i run

this there you go it gives us the

imaginary part which is 6

okay

now in python you can also perform

conversion of data types so you can

convert between different data types by

using type conversion functions such as

end float str etc

so let me define a

variable called num

which has a value 7.8

now

what i am going to do is

i'm going to create a variable called b

which is going to store the

integer part of num which means

initially i had defined num as 7.8 which

is a floating point number i want to

convert this num to integer type now

and

let me go ahead and

print

my b and i also print

the type of num

and

i'll then print

the type

b

let's

run this and see the result okay

so if you see here clearly

when i see

print b it has returned me 7 which is of

type integer so it has truncated the

decimal part

present in 7.8

again if i print type of num so num is

holding 7.8 it is of type float after

converting the float value into integer

it has given me int

okay

similarly

let's say we have another

number

minus 90.5

and

if i were to check the

type

i would write print type of num

then let's convert

this to integer

so i'll write print

in top num let's see the results okay so

initially minus 90.5 is of type float

after we converted

our

num

to integer it gives us minus 90 so it

has truncated the decimal point part

all right

now let's say i'll create another

variable let's say c equal to

let's say i'll write float

of

b

now if you remember

our b

holds a value of 7 if i were to convert

b to float again

i can use the float type conversion

function and let's go ahead and print

c

if i run this you can see here

previously

b was holding an integer of 7 now it has

converted that integer into a float

value so it is 7.0 now

okay

now moving ahead

let's see

about

boolean data types

so if i have a variable let's say

r

equal to

let's say it has a value called true

which is a type of boolean value

and let me go ahead and print the type

of r

it gives me

boolean

now let's say i'll write

num greater than c

let's

go to the top if you see here

num is holding a value of minus 90.5

and my c is holding a value of 7.0 i am

checking

if num is greater than c if i run this

it gives me false because

minus 90.5 is less than 7.0 and not

greater than 7.0

suppose

i create a variable

boolean or b double o l

and i'll store that value

num greater than

c

and let's

print

the type of boolean

i'll use type

of my variable that is bull

let's run it you can see it here it

tells us that

this particular operation is now holding

a data type of boolean

if you are getting confused we can

change the

variable here let's say i'll write

b underscore bull

and similarly i'll write here b

underscore bull

let's run it

you get the same thing

all right

now moving ahead

let's

explore how

string data types work in python

i'll give a comment as

string data types

scroll down

ok

so string data types or string values in

python are passed within

quotations suppose i have a string

called str1

and it has a value let's say

python programming so this is a text

value

i have another string let's say str2

which has a value

let's say simply learn

now

let's run this

okay

now if i were to check the type

of str1

it should give me string so str here is

a string

now you can also perform extraction

operations from the string suppose you

want to extract

the value that is present in my first

string that is str1 at index number five

let's run it

okay there is some error here

okay so this should be str1 and not strl

let's run it again

it returns us n

now let's count what is present at the

fifth index

so from our previous introduction to

python video you might be aware that in

python the index number starts with 0 so

if you count

p is at index 0

y is at index 1

t is at index 2 h is at index 3 o is at

index four and then

n is at index five so hence str one of

five returns and

similarly if you can

check for

other string that is string two let's

say i want to see the value that is

present

at minus

four

let's run it

it gives us e

now if you use a negative indexing

operation it will start counting from

the backward position so here

n is at minus 1 r is at minus 2 then you

have a

at minus 3 and e is present at -4 so

hence str2 of minus 4 returns e

cool

now you can also perform slicing

operation

suppose

i write str str1

i want everything that is present

between the zeroth index to

the fifth index

i'll run it

it gives me

h pytho so if you check

in string one

it will start counting from the zeroth

index and go up to

the fourth index and exclude the fifth

index

so in my string 1 if i start counting

from the 0th index so it is 0 1 2 3 and

4 so it will

print from p till o

and that's the result

okay

now you can also use some inbuilt

functions with string

suppose i write str2

dot

find

so i want to find the index where my

m is in simply learn

so i'll

write m within quotations and print it

it returns me 2

if you check again

so s is at 0th index 1 is at the first

index and m is present at the second

index

ok

moving ahead

let's explore a few sequence data types

so we'll start with

list data type

ok

now

first of all let me go ahead and

declare a variable called split 1

equal to

and this will have some

text let's say this

is

orange

then

i'm going to create another variable

called l1

equal to

i am going to

my variable or my

string that is split 1

using the split function

and i'm going to split using the comma

so you can see here my string has comma

i'm going to separate each of these

words with a comma

and let's print l1

if i run this you can see it here

initially my split 1 was of type string

and now we have converted

split 1 to a list you can see this this

is a list and it is present inside

square brackets to verify

you can use the type function so i'll

write type of

split one

it should return string you can see it

here str

and now if i write

type of l1

it gives me a list

okay

now let's see a few more examples i'll

create another list called

list1

and let's see it has some values

the alphabet a

we have

the number one which is in terms of

string again because i have passed in in

quotes

let's say i have india

let's make it consistent with single

quotations

and

let me

print what is inside list1

if i run it i get my list

now you can check the data type

if i write type of list one it gives me

it is a type

list

now you can also perform certain

operations on list suppose you want to

add a few elements to your original list

for that i'm going to create another

variable called list 2

and let's say list2 has some values

let's say b comma

2. now

if i write

list 1

plus

equal to

list 2

and let me go ahead and

print

list one

let's see the result

there you go so our initial list had

three elements a1 and india and now we

have merged or concatenated two more

elements b and two and hence this

becomes our final list

okay

now moving ahead

let's see

one more sequence data type that is

tuple or tuple

now list and tuples we have already

covered in our previous video on

introduction to python if you need to

brush up what list and tuples are you

can check the previous video

so i'm going to create a tuple that is

top1 and i am going to

store some values

tuple you can create using braces

i have some value let's say a

b

c

d

and let's say e

or let's just restrict it to d

now you can check the type of tup1

you can see here dup1 is of type tuple

now

i'll create another tuple let's say tup2

and

it has some values let's say e

f

and let's say g

now

if i

write

dup1

plus

equal to dup2

and if i print

my tup1

i get the result

of a merged

tuple

which has values of both top1 and tup2

you can see here our original tuple had

abcd and then we merged the second tuple

and it has

and it has given us efg as well and

hence this becomes the final tuple

you can also perform some basic

operations on tuple let's say i'll write

dup1 multiplied by 2.

you can see the result here

it has printed

my original tuple twice

okay

now moving ahead

let's see our mapping data type

that is dictionary

again dictionary is also covered

in our previous

introduction to python video

you can also have a look at that video

now the way to declare a dictionary

is

i'll create a variable

dict 1

and dictionaries are

written using curly braces

and have key value peers

so i'll write my first key as one and

let's see

this dictionary is about animals

and i have let's say lion

as my first animal in the dictionary

then i'll create my second key

let's see the second animal i have is

tiger

and let's see

my third element

is

a dog

let me run it

and print

my dictionary

you can see this

we have the dictionary printed

now if you want to check the type you

can write type of

dict 1

it returns us dict which means

dictionary

you can also print the length of

dict 1

and it gives us 3 which means our

dictionary has 3 elements

ok

now moving ahead

we'll explore

our set data type

now as we understood that sets are

unordered collections of

values

and these values are always unique

so i'll write set one

let me give a space

equal to

again sets are written within curly

braces

i'll create a set

let's say it has some duplicate entries

as well

and i'll print my set one

it returns only the unique values so it

has dropped

this 5 which was duplicated

you can check the type of set 1

it gives us it is of type or the object

is of type set

now

suppose

i have

another set called set 2

which has values let's say

a

comma

b

and let's say we have some numbers three

and four

i'll tell you the operation that i'm

going to do

i'm actually going to

do an or operation

so i'm going to print

set 1

or

set

2

so this is an or operator in python

let's print the results you can see here

it has printed

all the values that are present inside

set 1 or set 2.

so in set 1 we have 1 2 3 4 and 5

and in set 2 we have a and b

so it has dropped 3 and 4 because these

are not unique and

3 and 4 are also present in set 1.

suppose i were to perform an and

operation

i'll write set1

ampersand

set 2.

if i run this

you can see here it has only printed

the unique values that are present in

both set one and set two so three and

four are the unique values and hence it

has printed three and four

let's say

i'll write set one minus set two

let's see the results

it gives us only those values that are

present

in

set 1

and are not present in set 2 which is

this

let's see the result if i write set 2

minus set 1

so this will return the unique values

that are present in set 2 and are not

present in set 1.

so a and b are the unique values that

are present in set two hence it has

printed as a comma b

okay

now

another data type we had discussed was

range

so range is basically a function if i

write x equal to

range

4

and i'll print x

it gives us from 0 till 4 because in

python the first index starts from 0 and

goes

till 4 so the range is from 0 to 4.

now you can also print the type of x

it returns us a range

now we'll see

some binary data types

binary data types are not very often

used in python but it is better if you

know

binary data types can be written as x

equal to

b let's say i have a string

i'll write within double quotations

hello world

and let me go ahead and

print

my variable x

you see here

we have hello world

and now

let's print the type of x

you see here this is a binary type which

is bytes

i'll show you another operation let's

say you want to extract a specific

value

from a particular index

from this

binary data

so again you can use the

indexing operation

suppose i write print

i want to extract the value present at

the fourth index

it gives me one one one now this is very

interesting

let's

deep dive into this

let's check

what is present at the fourth index of

my string

so h is present at the zeroth index

e is at the first index

l is at the second index the second l is

at the third index and we have o

at the fourth index

so

when we are trying to print the index

position it is actually returning us the

ascii value of small o

now here i have a

doc open which is from ibm documentation

if you see

the

ascii value of small o or lowercase o

you will find

that the ascii value is one one one and

hence it has written us one one one

let's try for

another

index number let's say i want to find

the value which is present at index

number

minus

2

and if i run it

it gives me 108

so minus 2 means it will start from the

last index

so minus 1 is d and minus 2 is l

let's see what is the ascii value of l

if you see it here the ascii value of l

is 108

and hence it has written as 108. so this

is how

the binary data types work in python

now let's convert some

sequence objects to other type of

objects let's say i have a string

called s which has

something like

messy is from

argentina

now you can check

the type of s

fair enough it tells us that messi is

from argentina is of type string

now

what i'm going to do is i'll use my list

function

and pass in my variable that is s so

that it converts s to a list

and let me go ahead and print my l

you can see here

my string s has now been converted into

a list

and this is the result

see here these are all

list elements present inside square

brackets

now if you want you can check the type

of file

it should return us

list

and you can see it here

now suppose

i have

another list let's say l1 which has

some

numbers let's say

one 15

3

6

0

8 4 and 3

let's see we also have one

okay so this is a list you can check

type of l1 fair enough it tells us that

this is a list

now i want to convert this list l1 to a

set

now as we know that set only contains

unordered unique elements

so if i write s equal to

i'll use the set function and then i'll

pass in my list variable that is l1

and let's print s

it only returns me the unique values

present in the list so it has dropped

the

duplicate elements such as

three and one

now you can check the type

of s it gives us set

okay

so that brings us to the end of this

demo session on

data types in python let me go to the

top and

i'll brief you what we did in this demo

so first we looked at

the different numeric data types so we

saw integer data type then we saw

floating data type

we also had

complex data types

we saw how to extract a real part in

imaginary part from a complex number

then we used

some type conversion functions to

convert the numeric data types from one

data type to another so here we

converted a floating type data to an

integer type data

similarly

we saw how to use boolean data types

then we saw about string data types we

also performed some basic operations of

using

indexing method to extract

different values

we also saw how you can use slicing to

extract a range of values from your

string we use the find function to find

the index of a particular

character in the string

then we learnt the important

sequence data types like list

then we had

tuples

and then we learned about

mapping data types such as dictionary

we also looked at set data type

now

later on we explored about

range data type and we looked at binary

data types we saw how

binary data type returns ascii value of

a certain character

finally we converted

strings to list and then we saw how to

convert

list to sets

first we will learn different number

data types in python then we will learn

type conversion between number data

types and after that we will understand

how to represent binary hexadecimal and

octal numbers in python and then we will

understand different number functions in

python

a programming language needs to have

support for numbers to carry out

calculations in python the numbers are

categorized into different data types

types are implemented in python as

classes

there are three numeric types in python

int for integers float for decimal

numbers and complex for complex numbers

let's explore these data types in

jupyter notebook

i have opened my jupyter notebook and

now let's see different data types in

jupyter notebook

for example first we'll assign a number

to a variable

num variable equal to 7

and now we'll check the type of this num

variable for that we'll write the

command type

round brackets num round bracket close

and then we'll run this command

we will get int as the data type

now we will assign a decimal number to

the num variable that would be num equal

to 7.7

and now

we will check the type of the num

variable and

run this command

what we get is the float float as the

data type for the num variable

now we will assign a complex number to

the num variable

and we will check the type for this num

variable

and run the command we will get the

complex data type as the result

now if you want to get the real part of

this complex number

you just have to write the command num

dot real

and just execute the command you will

get 6.0

as the real part of this complex number

here you can see you just quote the

number in float data type

the complex number in python are stored

in flow data types whether it's the real

part or it's the imaginary part now

we'll see the imaginary part

num dot image

and now you will run this command you

will get 7.0

here also you can see that the imaginary

part is also stored as float

in python for complex number

now we will perform different arithmetic

operations with these data types

first we'll mention

arithmetic operations

now we will assign numbers to the

variables and perform different

arithmetic operations for that we will

assign

17 as a number to the variable num1

num1 equal to 17

and

the second variable num2 we will assign

the number 25

and now we will perform

different arithmetic operations first

we'll start with addition

so write the simple command that would

print

num1 plus

num2 and just run that command

you can see the result as 42. it's as

simple as that in python you just have

to write print and in round brackets

just write the operation you wanna

execute

now we will see the subtraction part

we'll write print

num2 minus

num1

and execute this command and we'll get

the result as 8.

now we see multiplication

print

num1

into

num2

and execute this command and we'll get

the result as 425

now we will divide

print

num2

divided by

num1

and execute this command

and we'll get 1.47

here you can see as we have assigned int

values to the num1 and num2 variable we

got the result for addition subtraction

and multiplication as in data type only

but for division we got it

as float

this is because python always gives the

output for division in decimal numbers

only

just to have minimum accuracy loss so

if you want to just get the output of

the division

as an end value you just have to perform

this

print

num2

and two slash signs and then num1 and

then execute the command

you will get one as the output so to

just get into the output of the division

you can use two slashes

next command we'll see is to raise a

number

to another number

so to just get 2 to the power 4 we will

write the command print

2

2 asterix symbols

and

4.

and just execute this command you will

get the output as 16

we got 2 to the power of 4

by just using two aztec symbols now to

get the remainder of the division

we just have to use the modulus symbol

so for that

print

4

modulus

2 and just execute the command

you will get 0 as the remainder

you can perform the same operations on

float numbers and complex numbers

now we will see

an arithmetic operation on complex

number

so we will assign a complex number to

variable

that would be g

equal to 1

plus

5 j

and another variable we will assign the

value 2

plus

3 j

and we will assign the operation

i equal to

g

slash h that is the reason

and

print the output

and will execute the command

we will get the following result for the

division of two complex numbers

now we will see type conversions in

python for that we will move

there are mainly two types of

conversions between numbers in python

first is using arithmetic operations

that is implicit type conversion and

second is using built-in functions that

is explicit type conversion

let's understand the concept of

conversion with the help of jupiter

notebook

so here

we will write first convergence

first we will assign a number

to a variable that would be a equal to

196

and we have seen in the previous

examples that its type is int

now if we put this number in two double

quotes

and now we'll check its type

that would be type

a

and run the command we'll get it as

string

so in python when we just put a number

in double quotes it will see it as a

string

and to get this number as an int

we just have to use explicit type

conversion for that we will write

b

equal to

int

a

and now we will check its type

type b

and run the command

we will get into

the data type for the b variable

the a variable is still the string data

type

and b variable has now turned as int

data type

and now

to turn a as a flow data type we can

write

c

equal to

float

a

and check its type

type

c

and run the command and here we can see

that it has turned into the float data

type

so a is still the string data type but c

has been converted the a variable into

the float data type

we can also convert the a string data

type into complex data type

just

we have to write t equal to

complex

and in brackets we have to write a

and we can check its type

and we can

print

the t complex number and we have just

execute the command

and we can see

that the complex number is 196 plus 0j

and we can also check its type

by just

writing print

type d

and we will run the command and we can

see that the class is complex

for the variable d we can define the

complex data type by different methods

one of the method is

we just have to write print

complex

and in round brackets we just have to

assign both real and the imaginary

numbers that would be 3 comma 6

and just execute the command

and here we got a complex number that is

3 plus 6 j

now we have seen the explicit type

convergence

now we will see some implicit type

convergence that is using arithmetic

operations for that we will assign

a float number that would be 2.6

to a variable

equal to 2.6

and

b equal to

6

and we will assign an arithmetic

operation that would be

c equal to a plus b

and

print the output

and execute the command

by using just arithmetic operations we

have seen that the addition of a float

number and the integer number turns out

to be a float number

so now we have seen the implicit type

conversion example

now we will see the representation of

binary hexadecimal and octal numbers in

python

all the integer numbers can be

represented as binary hexadecimal and

octa

to represent it as binary in python we

have to prefix it by using 0 small b or

0 capital b and for octal

we can prefix it by using 0

small o or 0 capital o

and for hexadecimal we can use 0 x or 0

capital x let's see this representation

in jupiter notebook

first we will write representation of

binary hexadecimal and octal numbers

now

we will first see

binary to decimal conversion

for that

we will first write

0

b

1 1 0

1 1 0 0 0

and then we'll just run it

and see 216 as the decimal conversion of

this binary number

now we'll see the same for the octal

for that we'll write 0

small o

12

and just run this command

and we can see that it has turned 10

in the decimal number system

for hexadecimal we will write

0

small x

and 12

and just run the command

and we can see 18 as the decimal

conversion of the hexadecimal number

system

we can also use 0 capital x

12 and just on the command

we'll see 18 the same output as of 0

small x 12.

let's see some operations with fractions

for that first we will comment fractions

now we will import the fraction module

for that we'll write from

fractions

import

fraction

s

f and first i will

execute the addition operation for

fractions for that will write print

f

1 comma 3

just for the fraction numerator would be

1 and the denominator would be 3

now we'll write the operation addition

and f

the second fraction that would be

okay we will write the same only one

comma three

and on execution of the command we will

get two by three as the output

we can also perform different operations

okay we will

just see the reciprocal of the fraction

for that we will write print

one

upon

f

five comma six

and just run the command

here we can see the reciprocal function

that would turn out to be six by five

now we will explore different number

functions

first one that we would explore would be

absolute

absolute function would turn any

negative number into the positive number

for that

we will just assign a number that would

be x equal to minus

9.8

and

we will just apply the absolute function

abs on the variable x

and just run the command

here we can see that has turned x equal

to minus 9.8 to 9.8

now

we will see some different functions for

that we will import the math

module

import

math

and we have different values stored in

the math module for example pi

we'll print the pi value print

math dot pi

and run the command

here we can see the value of the pi

3.1415926535893

we also have exponential value in math

module

for that we will write the command print

math dot e and execute the command

here we will get the value

2.718281828459045

for the value of e in the math module

now we will also see

exponential to the power 10

for that we will write the command print

math dot

exp

round brackets

10

and execute the command

we will get the value 22026.465

we can also perform log operations

for that we will write the command

print and we will get the log of 1000 to

the base of 10.

for that we'll write

math

dot

log

to the base 10

the would be

1000 and we will execute the command and

we will get 3.0

you can also get the factorial by the

math module

all right print

math

dot factorial

factorial of

6

and we'll execute the command and we

quote the factorial of 6

that is 720

now if we want the square root of a

number we will write the command

print

math dot

sqrt

and in round brackets we will write the

number for which we need the square root

we will write 25 and execute the command

and we will get 5.0

this square root number gives the float

number as its output

and we can also find out the maximum

numbers from a bunch of numbers for that

we have to write the command

max

round brackets

and the bunch of numbers from which you

want the maximum value

like 1 comma 33 comma 55 comma

7 comma 99 and just execute the command

you will get the maximum number that

would be 99 and if you want the minimum

number

you can write the command min

and in round brackets just write the

bunch of numbers

1 comma 3 comma 66 comma 88 comma

seven

and just execute the command

you will get the minimum number that

would be one

now you'll see the ceiling function for

that we'll write the command

print

math

dot c

and in round brackets we'll write the

number for which we want to use the same

function minus

43.5

and execute the command

you will get minus 43

so what the scenic function does is

it would give the highest value or the

greatest value for the number we have

entered in the ceiling function

now we will see the floor function for

that we'll write the command

print

bracket math dot floor

and we'll write the number for which we

want to use the floor function

minus

43.5

and execute the command

we will get minus 44.

so the floor function will give the

output value

just

below the or just the lowest value

of the value entered by us in the floor

function

now we'll see the power function for

that we'll write the command print

math dot pow and in round brackets

will write the number

2

and the power which we want that would

be 6

and just execute the command

here we can see

that 2 to the power 6 we have got the

output value as 64.

now we'll see some trigonometric

functions

first we'll see cos of x

like python number method cos returns

the cosine of x radians for that we will

write the command

print

math dot

cos of 0

and just run the command it will give 1

as the output

so

this method returns a numeric value

between -1 and 1 like which represents

the cosine of the angle

we will see another example for course

for that we'll write

print

math dot cos

and in brackets we'll write the angle

math

dot pi

and we'll execute the command

and we'll get the output as -1

now we'll see 10 trigonometric function

so the python method 10 it returns the

tangent of x radians

for that we will write the command

print

math.10

of angle 0

and we will execute the command

we will get 0 as output this method

returns a numeric value between -1 and 1

which represents the tangent of the

perimeter x

we will also see another example for tan

we'll write

print

math dot

10

math

dot

pi by

4 and execute the command

it gives us

0.999999 that turns out to be 1.

now we will explore some random number

functions for that we will write the

command

import

random

and import the random module

now we'll see the first function that

would be rand range for that we'll write

the command print

random dot

rent range and in circular brackets we

will write the range from which we want

the random number

that would be 10 comma 20 and execute

the command here we go 12 as the random

number

now we will define a list that would be

x

equal to

square brackets

one

two

three

four

and five

now we'll see another function

that would be choice and it would give

any random number from string

list or tuple

so for that we'll write the command

print

random dot

choice and in circular brackets we'll

write

or we will pass any list string or tuple

here we will pass this list

x and execute this command

we will get the random number three so

we are going to talk about object types

in python then we will see the different

type conversion functions that are

available in python

then we see the different types of type

conversion

all right

now let's look at the different types of

objects in python

so we have less

you have tuples numbers strings

dictionaries sets you even have file

objects

then you can see we also have other code

types such as boolean and none

then we have

program unit types like functions

modules and classes

now we will touch upon most of them in

the demo section of this tutorial then

we also have implemented related types

all right

now let's see how you can convert one

data type to another using type

conversion

so python provides two types of data

conversion techniques one is called the

implicit type conversion and the other

is called the explicit type conversion

now in implicit data type conversion

python can automatically

convert one data type to another data

type this process does not need any user

involvement

while in external conversions

users

convert the data type of an object to

required data type by using predefined

functions that are listed here so you

can see here we have the different

functions so if you want to convert a

specific value to an integer you can use

the int function we have the float

function

now we have something called as ord so

the ord function

accepts a string of unit length as an

argument and returns the unicode

equivalence of the past argument now we

also have

hex and oct so

the hex function

is used to convert an integer number to

its corresponding hexadecimal value

similarly the oct function will convert

the corresponding

or let's say we'll convert an integer

number to its corresponding octa decimal

value

we have tuple list set dictionary str is

for string you can convert a number into

a complex number by providing its real

and imaginary part

we also have this chr or the character

function

now this is how the basic general syntax

looks like you have the required data

type followed by the expression

okay

so let's head over to our jupyter

notebook and learn the different types

of objects as well as

look at the type conversions in python

okay so here i am on my

jupyter notebook let's first

look at

number objects so i'm giving a

comment

as number objects

all right let's see i have a variable

called num

which is equal to let's say 2

now

it's very simple that 2 is an integer

so if you want to check the type

you can just use the type function and

it gives us int which means integer so

here 2 is of

a type called number object

let's say you want to pass a floating

value

that's a 2.0

see the results

2.0 is of type float and again

2.0 or 2.0

is a number object

now you can perform various operations

on number objects suppose you want to

add a few numbers

so let's say 321 plus

365

and i'll say add

it gives us the addition of these two

numbers which is 686.

now let's say

you want to

perform a multiplication operation

let's say 62 multiplied by 2.5

if i hit shift enter it gives me the

multiplication of the product of these

two numbers that is

55.0

now

python by default will

convert the result to a floating point

number if there is one integer and this

one float

if you want to return the exponent of a

number let's say i want to know 2 raised

to the power 4

so i'm using double asterisks to

represent the exponent operator

if i hit shift enter it gives us 16. so

it's basically

two multiplied four times

now you can also

import specific libraries so let's say i

want to import the math library

and i want to print

the value of pi so here i have written

import math and then

using the module math i am

trying to find the value of pi let's run

it you see here it says 3.141 so on and

so forth

now you can also

import the random module let's say i'll

write

import random

and then

let's say i want to print a random

number

you can use the random dot

random function let's run it

you see here this is a

random value that

python has generated if i run it again

this value changes let's run it again

again this value changes

okay

now we'll shift our focus to

understanding string objects in python

so i'll give a comment string objects

let's say i have a string

a is equal to and let's say the string

has india

okay

now if you want you can print a it says

india

now suppose i want to

extract

the value that is present at the zeroth

index of the string so the way to do is

i'll pass in my

variable name that is a and within

square brackets i'll give the index

value that is 0. now one thing to

remember in python the index value

starts with 0 and not 1. so if i do

a of 0 it gives me i because i is

present at the 0th index

now let's say i want

the last value

in this string india so i need to return

a for that i can use negative indexing

by using minus 1

if i do minus

1 it gives me

a which is the

element present at the last index

now let's say

i'll write a

1 and colon

let's run it

you see the result here it says ndia

which means python has returned

everything starting from the

first index

till the last index

so here colon means you need to return

everything that comes after the first

index

now

let's see

i'll write

print

a

and i'll add

let's say xyz

run it

you see here

this xyz has been concatenated with the

value that was present inside a that is

india so the result is india followed by

xyz

okay now

if i write a multiplied by

7

it will print

india 7 times without a space

you can see it here

cool

now let's say you want to replace

certain values

in the string you can use the replace

function so if i write a dot replace

let's say i want to replace ia

that is present in india

with let's say

xyz

let's run it

you see here

ind is fine after that we have ia and

that ia has been replaced by xyz

now let's move on and understand

list objects in python so i'll write

list objects

okay

so let's go ahead and declare a list l1

within square brackets

let's say we have

values like 101

let's say

america

and then let's say we have another

floating value let's say 2.05

this is my list if you want to print the

list you can use

l1 to print it you see here this is my

list l1

now if you want to find the

length of l1 you can use the len

function

if i run it

you get 3 which means there are 3

elements in the list 101 america and

2.05

now if you want to extract certain

values from the list for that you can

use the indexing method let's say i'll

write

l1 of

1

that gives me america because

at index position 1 we have america so

101 is at the 0th index america is at

the first index and 2.05 is at the

second index

next

let's say i write

l1

and then

i give colon -1 let's print it so that

gives me

101 in america so what it does is

this colon minus 1 will exclude the last

index and print the other two

elements in the list

okay

now if you want to

append

some elements to the list you can use

the append method so i write l1 dot

append

within brackets i'll give my value let's

say

usa

now let's go ahead and print l1

if i run it you can see the difference

earlier

my list had three elements 101 america

and 2.05 now we have added the fourth

element that is usa

cool

now you can also use the

pop function in

python let's see what it does

so i write l1 dot pop and i'll give

let's say three

if i run it it returns me

usa because usa is present at the

third index of my list

if i write pop one

it gives me america because

america is present at the first index

all right

now you can also

reverse the elements in a list if i

write l1 dot

reverse function

if i run this and then i'll

print l1

you see the result here we have 2.05 and

101 which is printed in reverse order

the reason being

we have already popped america and usa

out and we are only left with 101 and

205 and if you reverse

the current list

it will be printed as follows so 2.05

comes

at the beginning and then we have

101.

let me just

rerun my list again to show you the

difference

i have run my l1

let's run this append query

and now

let's use the

reverse function there you go

so now our original list has been

reversed so you have us at the beginning

and 101 towards the end

okay

now moving ahead let's see

the next type of object in python that

is dictionaries

okay

let's see i'll create a dictionary

called dict 1

and you might be aware that dictionaries

are created using the curly braces

so i'll have my

key value pairs let's say my key is 1

and the value it holds is let's say

the names of animals

tiger

comma we'll have the second key and that

second key will have the value let's say

lion

and let's see

we have another element with the third

key

and let's see

we have mouse

okay

now

let's print our dictionary

so this is how my dictionary looks like

now

you can

display the keys

by using the keys function

so this will return all the keys present

in the dictionary you see here 1 2 and 3

are my keys

similarly

you can display the values in the

dictionary

you need to change this keys to values

if i run it you see here

tiger lion and mouse are the

three values

now suppose you want to add another

element to your dictionary for that you

can write

dict 1

and give the

fourth key equal to

the value let's say cat

now let's run

dict 1 and see the difference

there you go so here we have added

another element to the dictionary which

is cat

now moving ahead

let's explore

double objects

okay so we'll create a tuple called t1

equal to

we'll have the values 1 comma 2 comma 3

comma 4

and let's say you want to print the

length of tuple t1 it gives you 4

because we have 4 elements in the tuple

t1

now let's say i'll declare

one more tuple called t2 and this time

we'll have two more elements in the

tuple so i'll write t1 plus

followed by the two elements that i want

let's say 7 comma 9

and i'll print t2

if i run it

you can see here we have added 7 and 9

to our original tuple that had 1 comma 2

comma 3 comma 4.

now you can also use the indexing method

or the slicing

technique to extract values from the

tuple let's say i write

t2 of 3 it will return the third element

that is present in tuple

d2 so if you see here

my

third index has the element 4 hence it

has returned four

cool

now moving ahead

let's see

how file objects work in python

all right now

using python you can create

files

let's say i want to create a text file

in python using the jupyter notebook for

that i can write f1 equal

to i'll use a function called open

and inside this open function i want to

create a text file and first

i'll write something into that file

let me show you so this is a folder that

i have

the folder name is called object types

and it is present in my desktop so i'll

use this location

and here you can see now this folder

contains no files as of now but we are

going to create text file using python

let's see how to do it

so here i'll paste my

location that i just copied

now one thing to note is you need to

convert everything to

forward

slash or you can use

double backslash also

i'll give

another forward slash

and let's say i want to

create a file in the name of data.txt so

it is going to be a text file

make sure everything is

inside single quotation

and i want to open the file in

write mode so i'll write w here let's

run it and see the difference

now if we check our folder

you see here earlier there was no data

file now we have created a text file in

the name of data you see here there are

no

information or data inside this text

file next we are going to add some data

to this text file

let's

go back to our jupyter notebook

okay

so we'll write some data to that file so

i'll write f1 dot

after that i'll use the write function

and within single quotations i'll write

let's say hello

simply learn

and then

i'll give backslash n to go to the next

line

i'll write again f1.write

and i'll pass in another message let's

say welcome to

python programming

and we'll give another backslash

followed by n

and then finally we'll close the file so

i'll write f1 dot

close function

let's run this

and we'll see the difference now

if i open this the yuko

we have some data in this

text file that is hello simply learn

welcome to python programming

so this is how file objects work in

python

all right

now moving ahead we'll see

how

sets work in python

suppose i create a set called s

and i'll use the set function

and i'll pass in

india

so this is a string

and i want to convert the string to a

set

let's say i have

another set called s1

and here i have

a list of values let's say u

s

and let's say a

now if i write

s comma

s1

so what set does is

it will return only the unique values

that are present inside each set so here

if you see

india

all the elements are unique except i

because i is repeated twice so it will

return i only once in the result but usa

has all the elements present only once

so

set will return all the elements

now what if i'll

write let's say s

ampersand

s1

so

this will give me only the

common element that is present in both

the sets so if you see here in india and

in u s and a

only a is repeating in both the sets so

it gives me a

suppose i write

s

this is the or operator and i'll write

s1

if i run it it gives me

all the elements that are present inside

set s and s1

excluding the repeating elements so here

i is repeating so it has printed only

once

similarly you can write

s minus s1

so you get

only

those elements that are present inside

set s and are not present in set s1

now in set s e is present as well as is

present in set s1 so it has excluded e

from the result

okay

now we'll see some operations let's say

i'll write equal to 7

and be equal to let's say 2.0

i'll

add a and b and store the result in

my variable r which stands for result

let's see

the output if i write print r

it gives me

9.0

and if i check

type of r it gives me

there's a spelling mistake i'll write

type of r it gives me float so here

python is performing

implicit

type conversion so if you add an integer

with a floating point number the result

will be a floating point number and not

an integer

now if you

say equal to 7

and let's say b equal to same 2.0

and this time i am explicitly defining

my result to be an integer so i am using

an integer function so if i write a

plus

b

and if i print r

you see the result it has given me an

integer which is

9.

now to verify you can also use

type of r

it gives me integer but earlier

it returned us float

so this is how

implicit

and explicit conversion

work in python

now this example was for numbers

similarly you can

also

perform for strings

and for less tuples and sets

moving ahead

one thing i wanted to tell you was you

cannot add a string

and an integer

suppose

i'll give a comment

string

and integer addition

suppose i have a variable called a which

has a value of a 7 so 7 is an integer

here then i have a variable called p

which has a value 2 but this time i'll

assign this to within

quotes so this becomes

of type string

now if you want you can check that as

well if i write type of 2

rather type of b it will give us str

which means string

now let's see

i'll write r which stands for result

equal to

a plus b

now if i print r

it will give us an error because you

cannot add a string with an

integer

so it says unsupported operand

the way to fix this is you need to

convert this string into an integer

explicitly

so this time we'll say equal to 7

b

equal to

2 so

it is a string

now i'll write

r equal to

a

plus

i'm going to use the integer function or

the int function to convert my b to an

integer

and then i'll print r again let's do

this there you go so here we have

converted my string value to

a numeric value

of 2 and this time it works fine so 7

plus 2 is 9

okay

now let's see how you can convert a

float value or a floating number into an

integer number let's say i have a

variable called a which has a value

let's say 77.9

and i'm going to create another variable

called int underscore a

and i'll pass this to my integer

function

so it has int of a

now let's print

int underscore a

so you have 77 so

my integer function has truncated the

decimal point value that had 0.9

if you want to check the type you can

use

the type function i'll write type of

hint underscore a

so it gives us integer

now you can also convert an integer to a

floating point value

so if i have a variable called a that

has a value of let's say

50

and if i write float underscore e equal

to i'll use the float function to

convert the

variable e to a floating point value

and let's

print float underscore a

so it gives us 50 50.0 instead of 50.

you can also check the type

of float a

it gives you float

okay

now you can also convert an integer to a

complex number

let's say i'll take the same value equal

to 50 i'll write comp underscore e which

stands for complex a

i'll use the complex function

and pass in my

variable that is

e

now let's

print

comp underscore a

so it gives us

50.0 j so 50 is the real part and 0 j is

the imaginary part

you can also convert an

integer to a string

i'll take the same value let's say 50

i'll write str underscore a equal to

str of a so i'm using the string

function to convert my integer to a

string

let's print str underscore a

it should be an underscore and not an

hyphen

let's run it there you go you have 50

within single quotes

you can also check the type of

a htr underscore a it gives you string

cool

now

we learn how to convert a string to a

tuple

so let's say i have a string that has

india as its value

if i write

ts equal to

i'll use the tuple function and pass in

my variable that is s

and then we'll print ts

you can see here

python has converted my string s which

had india into a tuple of individual

elements

and my tuple is present inside brackets

cool

now similarly you can convert a string

to a list

i'll use the same string as equal to

india

and then let's say i want to convert it

to a list i'll use l1 equal to

followed by the list function and inside

the list function i'll pass in my

variable that is s

and let's print l1 and see the

difference

you see here

my string has now been converted into a

list you can also check the data type of

l1 or the object type of l1

it returns you list

similarly you can also check the type of

ts

it gives you tuple because we converted

that

string to a tuple

now let's explore how you can convert a

tuple to a list let's say you have a

tuple called t

and it has a list of names let's say

john

we have mary

then we have let's say mark

now to convert into a list we'll use the

list function again let's say

l2

equal to list of

t

and let's print l2

so this is a list because it is present

inside

square brackets

you can check the type of

t

so t is a tuple you see here

if i change this to l2

it gives you list

cool

now

moving to the next section where we'll

see how to convert

integer to binary

suppose i have a variable called a equal

to

10

and then

i have p equal to

bin of

let's say we have another variable which

is c

and here i want to convert my integer

into a

hexadecimal value or a

octa decimal value for that you can

write d equal to use the oct function

for

octa decimal value

okay

now we are going to print them one by

one

so i'll write print off b

print of

c

and then we'll print what is there

inside d

we'll run it and you can see the results

here

so binary of 10 you see here

hexadecimal of 10 you see the value here

this is an extra decimal value

then we have the octa decimal value of a

okay

now moving to the

final section of this demo

you can convert a number to its

corresponding

ascii character

let me show you how to do it

suppose

i have

n1 equal to

76

now if i write

chr

of

n1 and run it it gives me l

now let's see our ascii table so this is

my ascii table and

for 76 you can see here the character is

l

so this

chr of n1 will return

the corresponding ascii character for

that particular number so here 76

belongs to l

let's say we have another number n2

equal to let's say 100.

now if i write chr of

n2

and run it it gives me

lowercase d

we'll see the table again

and if you see for 100 we have lowercase

d

now here you have a list of characters

these are special characters you have

uppercase characters you have add the

rate you have numbers each of them have

their own ascii values

cool

now

you can

convert string character into unicode

values now let me tell you what unicode

value is so computers on a basic level

deal with numbers so letters that appear

on computers are stored by computers as

a list of numbers

so the unicode standard provides a

unique number for every character and

supports multiple languages and all

special characters

so let's say i have a string s which has

the value of capital a or uppercase a

if i write r which stands for result

equal to

ord so this is the function which

converts a string to a unicode value

i'll write ord of s and will print r

if i run it it gives me 65

so

65 is the unicode value of a

now you can also have digits let's say i

have 7

i'll run it

so 55 is the unicode value of string 7

let's try for any other letter let's see

v

and run it you have 86

okay

so we'll understand what is a string in

python

and how to create strings in python

then we look at the different string

methods and how to perform string

indexing

and

all these will see with the help of

hands-on demonstrations on the jupyter

notebook

so let's understand what is a string

so a string in python is an object that

represents a sequence of characters

in python we have str as the data type

of string

now you can create strings

using single quotes or double quotes so

here is an example

where we have used a single quote to

write a string so our string is hello

india which is inside a single quote

below if you see we have the same string

written within double quotes so these

are the two methods in which you can

create strings in python

now you can also use triple quotes which

are generally for

multi-line strings or dot strings so

here is an example we have a string

called str3

and

the content it has is human psychology

is an interesting subject now if you

print the string it will be printed in

two lines and not in a single line

now we'll be exploring much more in

detail in our demo session so please

wait for a while next

we have string indexing so if you want

to extract a few characters from your

string you can use the indexing method

so in python

a string starts with the

index number zero

so here we have a string which is

healthy

and

the first element is present at the

zeroth index so at the bottom you see

the forward index on the top we have the

reverse index or the negative indexes

so in python as i said the first index

is at the zeroth position so h is at

zero e is at the first index a is at the

second index so on and so forth now

similarly if you look at negative

indexing it starts with minus 1 in

reverse order so we have minus 1

for y minus 2 for h minus 3 for t and so

on and so forth

now let's head over to our jupyter

notebook where we'll

learn about strings in python in detail

okay so i'm on my jupyter notebook first

i'll create a

new notebook i'll click on new and then

select python 3

ok

so here let me

rename my notebook as

strings in

python demo

i'll click on rename

okay

now let's start with our first example

i'll create a variable called str1 that

will have a string

you can see here i am using single

quotes now i'll write hi

sam

so here

str1 is holding a string called hi sam

and let's go ahead and print the string

str1

i'll hit shift enter to run it you see

here i have my string printed hi sam

if you want to check the

data type

that str1 holds

you can use the type function and inside

the type function i'll pass in my

variable str1

if i run it you see here it gives us str

which means

it is of type string

now let's create another string str2

using double quotes this time so i'll

write let's say

hello

angela

i can give exclamation mark

okay now let's just print the

second string you see here this is my

second string which is hello angela if

you want you can also use the print

function here

and run it you get hello angela

now let's write a multi-line string

using triple quotes so i'll write str3

equal to

i'll use triple quotes

and then

i'll say

hi everyone

go to the next line i'll write today

we will

learn

about

i'll go to the next line and i'll write

strings in python

then i'll again give triple quotes to

close my string

and let's just print this str3

if i run it you can see it here i have

now written a multiline string hi

everyone today we will learn about

strings in python let me just add a s

there you go

okay

now coming to the next topic we'll learn

about indexing

all right

let me declare a string str1

which has

value as simply loan

now

to use indexing and extract certain

items in a string or values in a string

you can use square brackets and inside

the square brackets you can give the

index position

for example if i write str1

and in the square bracket i'll give

let's say

i want to

find the element or the value present at

the zeroth index

let's run it it gives me s

because as we learnt in the slides

the first index in a string

starts with the zeroth number

so i have s in my zeroth index so hence

it has printed s

let's explore a few more if i write str

one of let's say i want to know what is

present at the third index if i run it

it gives me p you can check now so s is

at the zeroth index i is at the first

index m is at the second index and p

is at the third index

let's say i'll write str str1 of

let's say 12

we can see the difference now it gives

us an error it says string index out of

range the reason being simply learn

does not have any value at the twelfth

index so it's printing an error saying

string index out of range

now let's change this to

six and see what we have at the sixth

index we have l

if you count here s is at the

zeroth index i is at the first index m

is at the second index p is at the third

index

the first l is at the fourth index

again i is at the fifth index and then

we have the second l at the sixth index

so we have l printed here

now

let's see how to use

the slicing operator using colon

i'll write

slicing operator

okay

i'll use the same string as tr1 let me

print it once again we have simply

learned

suppose i write str1

within brackets i'll use the slicing

technique now i want everything starting

from the zeroth index

i get simply learn so here i am printing

everything that starts with the zeroth

index

next let's see

what we have

if i print my string str1

and write 1s to 6

i'll run it

it gives me impli so if you notice here

i want to extract whatever is present

from the first index

till the sixth index but excluding the

sixth index so in python

the indexing method or the slicing

method will exclude the last index so

here if you see

i is at the first index m is at the

second index p is at the third index

l is at the fourth index

and then we have i at the fifth index

and we have excluded the sixth index

that is the second l so hence it has

written us impli

now similarly let's see

we'll see another example i'll write

str1

this time i'll use colon

6.

if i run it you get

simply

so it has printed everything starting

from the zeroth index till

the sixth index but excluding the sixth

index so you have all these values

from zeroth index till the fifth index

okay

now you can also

reverse a string for that you can use

negative slicing using

two colons

if i write print

str1

and within square brackets i'll give

colon colon -1

let's run and see the result

there you go if you see this it has

printed my original string which is

simply learning reverse order now

so this is a very simple method if

someone asks you to reverse a string or

print something in reverse order you can

use the negative slicing method

now let's explore a few more example

if i write str1

and within brackets i'll give minus 1

and run it

it returns me n because in my original

string if i go on the top i have n at

the last index which is

here -1

similarly let's see what we have at

minus

3

we have a here if i go to the top

you see here

n is at minus 1 r is at minus 2 and a is

at minus 3 and hence it has given us a

now let's say i'll write str1

i want to print

minus 2

colon and let's see the result it has

given us

r and n

so here we are printing

only the

last two elements in the string hence we

have used -2

okay

now python does not allow you to

reassign values

in a declared string let me show you

what i mean

i'll give a comment here

reassign

strings

suppose

i have the same string str1 which is

simply learn

say i write str

and i want to replace

the value present at the third index

with let's say

o

and

if i were to print

str1 now

python will throw an error saying str

object does not support item assignment

so it is immutable

like tuples where you cannot reassign

any

values

you can also

delete a string

see i have another string called str2

which has a value of

let's say python programming

you can use the dl keyword

and write str2

and now let's print str2

you will see

that

it says name str2 is not defined because

we have already deleted str2

the above stuff

okay

now let's go ahead and see some of the

important

string operations

okay

see i have

str1

which has

python

now one thing to note i am using either

single quote or double quote you can use

whatever you want

let's say i have another string which

has programming

so these are my two strings

let's

perform a few operations on these

strings

see i write

str1

multiplied by 3

and i'll run it

you can see here it has printed python

thrice because i have said str1

multiplied by 3 so in str1 we have

python and multiplying 3 returns python

3 times

now let's see i'll write str1

plus

str1

it has merged python twice so i have

python and python repeated

let's say i write str1 plus str2

we see the result it gives us python

programming so basically

if you use

the plus operator with two strings

python will perform a concatenation

operation which means it will merge both

the strings

now if you want to find if a specific

character is present in a string or not

you can use the in operator for this

let's say i'll

print whether

w

is

present in

str

1

but run it it gives us false because in

str1 we have python and if you see here

we don't have the letter w in python and

hence it has given us false

let's

now let me copy this

i'll paste it here let's try whether o

is there in

string one or not it gives us true

because we have

an o here

you can see here we have an o

similarly

let's say

i want to find whether

l a

is there in string

2 or not

but run it it gives us false because in

string2 we have programming and we don't

have any la

present in programming

let's say we'll see whether r o is

present in

string two or not

this time it returns us true because if

you see here we have ro in programming

and hence it has given us

true

now you can also

print a raw string using the

r alphabet

so the way to write is i'll write r

give a

single quote let's say i'll give a

location

c drive

two forward slash and let's say i'll

write

python 3.7

and run it it gives me a raw string

now

let's see some formatting methods i'll

write

a comment saying

format methods

okay

i'll write a print statement

i'll give double quotes and here

let's see the first example where i'm

using

curly braces i'll write

and

i'll give another curly braces

you'll get to know what i'm doing once i

finish this

let's say i have a message

both are

best

friends

then i'm going to use my format

method

and inside this i'll pass in my two

values for these braces

so these curly braces will be replaced

by

the words that i

pass in or the values that i pass in

within the format method

so here i'll write let's say

james

and my second person would be

brad

now let me run it

you see here

what python does is it replaces

the curly braces with

the names that have passed within the

format method so it takes the first

argument for the first curly brace

and the second argument for the second

curly brace

so my statement becomes

james and brad

both are best friends

now let me just copy this i will show

you another example

this time i'll

give 1 and

0 inside the curly braces

now if i run this

there you go

so here

james is at the zeroth index so this is

basically a list where james is at the

zeroth index and brad is at the first

index so if i write 1 and 0 it will take

brad here

and then

for zero it will take james so now my

message becomes brad and james both are

best friends

now let's try out another example i'll

paste it here

i'll use

two variables let's say a and b

and inside my format method

i'll write a equal to james

and i'll assign b as brad

let's run it

there you go we have our message printed

james and brad both are best friends so

here a refers to james and b refers to

brad

cool let's explore another example

i have a variable called name and that

has a value

angela

and then i have another variable

it's a salary

of

100 000

i'll use a print statement

i'll print a message

her

name

is

i'll

use percentage

s for string

give

a backslash n for next line and i'll

write

her

salary

is

then i'll write

percentage d

this is for numbers

and then i'll give another percentage

and let's see i'll write

my two variables niemann's salary

let's

see what we have in the

result

i need to close my double quotes here

i'll exclude it from here let's run it

there you go so i have my message here

her name is angela her salary is

hundred thousand dollars

i'll just

delete this piece here we'll run it

again okay

now this percentage s

refers to the name

and we have declared her name is angela

so my first statement or the message

becomes her name is angela

and the next

message is her salary is percentage t so

percentage d here refers to the salary

where we have 100 000

so the next message is her salary is 100

000

so these are the very basic and

important

print methods or formats that you can

use

while working with strings

now we'll explore a few

functions that are readily available in

python to operate with strings

i'll take my same string str1 as simply

learn

and then

i'll create another variable called str2

i'll write str 1 dot i am going to use

the

capitalize

method

ok

let me make one correction i am going to

write everything in lower case so that

we can see the difference how

we can capitalize the string

so i'll write my print statement print

old value

this is going to my message

i'll give a colon

followed by my double quotes and i'll

pass in my variable str1

okay

now i'll copy this

in the next line we have

a new value as str 2.

let's run it and see the difference

there you go so here my old value has

simply learned in all

lower case but when i used the

capitalize method

so python has converted my first letter

and simply learned to

uppercase or capital keys

cool

now let me copy this

i'm going to use the same example

for

the next three methods

let me show you how the case fold method

works

this time i'm going to pass my input

string in all upper case i will write

simply learn in uppercase

and instead of capitalize i'll write

case fold

let's run it and see the difference

there you go

initially we had simply learn in

upper case and now we have converted

into case fold so

all the letters are in lower case

now moving ahead

you can also use the

upper method to convert a string into

upper case

let's say i have a string

where

few of the letters are in upper case and

few of the letters are in lower case

this time i am going to convert

everything into upper case so i'll use

the upper function instead of case fold

let's run and see the result there you

go so this time

python has converted my original string

into uppercase

and likewise you can also use the

lowercase

instead of upper if i write lower you

see here everything has been converted

to lower case

cool

okay

now i'll show you how the

title method works

so in title method all the words

basically the first letter of all the

words will be in upper case so suppose i

have

a string

which is

simply learn

company so i'll write

let's say

this is my string and i'll

i'll convert my str1 to title case

let me run it

so this is the difference you can see

the first letter of the first word is

upper case

again

the first letter of the second word is

also in upper case so this is how the

title

case works

you can also count the occurrences of a

particular

element in a string

suppose i have string one

that has python programming

in str2

i'll write str1 dot

and use the count function to count how

many times let's say n the letter n is

present

then i'll print

saying

occurrences

give a colon here

and then i'll pass in my variable that

is str2 so this will count the number of

times

n is present in my original string so if

you see here

in python programming we have n present

twice

similarly let's check for

g

the letter g is also present

twice

let's see for y

now y is present only once which you can

see here

okay next

let's see how the

replace function works in

python

i'm giving a comment as replace

so let's say i have a string str1

which has

hamburg

is

located in

france

so hamburg is a city which is actually

located in

germany and not in france so using the

replace method we are going to replace

france with germany

so what i'll do is i'll create another

string str2 equal to i'll write str1 dot

and then i'll

use the replace function

and i'll say replace

my string france

with

country

germany

and then we'll print str2 and see the

result

there you go

so we have changed

hamburg is located in france to hamburg

is located in germany

now coming to the final method that we

are going to explore in this

python strings demo which is

using the split function

okay

so you can split the values for each

word in a string as separate

words and store it in the form of a list

so i

write str1

i'll just copy this

i'll paste it here

and i'll change france to germany

because hamburg is actually present in

germany and not in france

and then i'll create another variable

called str2

i'll write str1 dot

and then use the

split function

now let me print both the strings first

i'll print str1

and then i'll print

str2

if i run it you see

my original string was hamburg is

located in germany and then using the

split function we have

segregated or divided

each of the words present in the

original string into separate words and

this time it is present in the form of a

list let's see what operators are in

python

now operators are generally used to

perform operations on values and

variables in python

these are standard symbols used for

logical and arithmetic operations

the value that the operator operates on

is called the operand

so here on your screens you can see the

different types of operators available

in python

first we have arithmetic operators so

arithmetic operators are used to perform

mathematical operations

it returns either true or false

according to the condition

so these are the comparison operators

you have

less than greater than less than equal

to greater than equal to we have not

equal to and we have equal to equal to

third we have

assignment operators so assignment

operators are used in python to assign

values to variables so these are the

assignment operators you have equal to

you have plus equal to

so for example you have a variable

called x

and if you say x plus equal to 7 this

means

it is x equal to x plus 7.

similarly if you say x minus equal to 7

this means x equal to x minus 7

and similarly you can

see the other assignment operators here

next up we have the

logical operators so logical operators

are used in

the expression evaluation to make a

decision if both the expressions are

true

then the condition will be true for an

and operator

for an or operator if one of the

expressions is true then the or

condition will be true

now for not

if an expression a is true then not e

will be false

we also have

bitwise operators so bitwise operators

act on operands as if they were strings

of binary digits it acts on bits and

performs bit by bit operation so hence

it is called bitwise operator

so here each value is evaluated as

zeros and ones

then we have identity operators so

identity operators are used to check if

two values are located on the same part

of the memory

two variables that are equal does not

imply that they are identical we'll

understand each of these operators in

the demo session on the jupyter notebook

and finally we have membership operators

so membership operators are used to test

whether a value or variable is in a

sequence so you have is

and is not as identity operators in

membership operators we have in and not

in now let's head over to our jupiter

notebook and we'll see

and explore all these operators one by

one

so i am on my jupiter notebook operators

in python

so let's first start with arithmetic

operators

i'll just

give a comment here saying arithmetic

operators

okay

first up we'll see the addition operator

for that let me assign

two

variables so i have assigned a variable

x to a value 10

and let's say we have the second

variable y equal to 4.

now

if i say print

x

plus

y

it will perform an arithmetic operation

that is addition

and will sum the result

of x and y and gives me 14 because 10

plus 4 is 14.

then let's say

i'll write print

x

minus y

that gives me 6 because 10 minus 4 is 6.

similarly you can have

multiplication as well so i'll write x

asterix y

that gives me

40 because 10 multiplied by 4 is 40.

similarly

let's

say x

divided by

y

it gives me 2.5 which is basically the

quotient

of these two operands

all right

now

if you were to find the

remainder you can use the modulus

operator so i'll write x modulo y it

gives me 2

so you divide

10 by 4 the remainder is 2.

now you can use the

double asterisk operator which is

basically

known as power

so the left operand is raised to the

power of right

i'll write print

x

give to asterisks and then say y

it gives me 10 000 so what basically

python does is

it will raise 10 to the power of 4 so 10

is multiplied 4 times and the result is

10 000

you can also try out another example

let's say 2 raised to the power of 4

this gives me

16.

if i say 2 raised to the power of 3

that is 2 cube and the result is 8.

you can also perform flow division

so flow division results into whole

number adjusted to the left in the

number line so if i write print

x

and flow division is

given by 2

forward slash

then i'll write y

that gives me 2 so it returns a whole

number

a generic division gives me

2.5

that has the floating point value but a

flow division will give me a whole

number

adjusted to the left on the number line

all right so these are some of the basic

arithmetic operators that are very

popular in python

next we'll move on to

assignment operators

i'll give a comment as

assignment operators

okay

let's assign a value x equal to 7

so here we are assigning the value of

7 to x

and

your equal to is an example of

assignment operator

now if i print x it will give me 7.

let's say i'll again write x equal to 7

and in the next line i'll write x plus

equal to 3

and will print x

so what python does is

it adds 3

to my original value

that x holes that is 7 so here x plus

equal to 3 means

x equal to x plus 3

so

x equal to x plus 3 can be written as x

plus equal to 3

similarly

you can also

write x

minus equal to something

say x equal to 7 and then i write x

minus equal to

3

then we'll print x

this gives me 4

because

we are subtracting the original value of

x by 3

so here x minus equal to 3 means x equal

to x minus 3

okay

similarly let's say i'll write x

asterix

equal to 3

if i run it

and print the value of x it gives me 12

because our previous x value was 4 and

now we have multiplied x by

3 so x

value now becomes 12.

let's say i'll write x

divided by

3

and i'll print x it gives me 4.0 this is

a floating point number so we are

dividing

12 by 3 and the result is 4.0

cool

if you want you can also perform

an exponent operation

or a power operation so let's say i have

x equal to 7

and then i write x

double asterisks equal to

say 2

and then we'll print x

okay there is an error here let's debug

the error

i have put a space here let's delete

that space you have to keep this in mind

now let's run it there you go so 7

raised to the power of 2 which is

basically 7 square is 49.

you can change the values and

run other examples let's say 10 raised

to the power of

3 we have 1000 as the result

okay

now moving ahead

now we'll understand about

comparison operators so i'll give a

comment

as

comparison operators

okay

let's say i have x equal to 7 and then i

have y equal to

3

if i print

x equal to equal to y

it will give me false the reason being

the value that x holds is not equal to

the value present in y these are two

different values that x and y hold so x

is not equal to y

and if we print x equal to equal to y it

will give us false

now

i'll just copy this code

i'll print it

here

and instead of equal to i'll give not

equal to

so not equal to is represented by an

exclamation mark followed by an equal to

if i write x not equal to y

this gives us true because x and y are

two different values and they are not

equal

i'll print

my code again and this time let's say

i'll write

x

greater than

y

it gives us true

because 7 is greater than 3

if i write x less than y

and hit shift enter that gives me false

because 7 is not less than 3

i'll print the code again this time

we'll see

if x is greater than equal to 3

if i run it it is true because 7 is

greater than equal to 3

and

now let's check for less than equal to

this is false because

7 is not

less than equal to 3

okay so these are some of the

basic comparison operators that are

available in python

now moving ahead we'll see

how logical operators work in python

okay

first

we look at the and operator

in python

suppose i have a value

of 7 stored in x

and then i have a value of 12 stored in

y

if i write

print

x greater than

2

and

y

less than 10

let's run it and see the result it gives

us false

now

and logical operators

will return true

if both the

conditions are true

and it will return false even if one of

the condition is false

so here

x is greater than 2 which means 7 is

greater than 2 is true

but

y

less than 10 which is 12 less than 10 is

false and hence our entire expression

becomes false

next let's see i have x equal to 5

and then

i'll print

x greater than 3

or x

less than

10. if i run this

it returns as true the reason being

x greater than 3 is true which means 5

is greater than 3 that is true

but 5 is

not less than 10

but

since one of the conditions is true so

the or operation in python returns us

true

now

let's see another example

i'll write x equal to 5

and

y equal to

10

i'll print

x

greater than 10

or

by

less than 20

if i run this

it returns true

so let's see our expression

x greater than 10 that is

5 greater than 10 is false but

y less than 20 so 10 is less than 20 is

true so our or operation will give us

true since one of the condition is true

now moving to the next logical operator

we have not

i'll given

comment here as r and now we'll see not

let's see i have x equal to 5 and then

i'll

print

x than

3

and

x less than 10

this should ideally give us true the

reason being x is greater than 3 and x

is less than 10

let's run and verify okay so this is

true now let me copy this and i'll paste

it in the next cell

now i'll replace

my above print statement with a

not operator

and we'll close our print function with

another bracket

now let's run it

so this will give us

false because

my

expression evaluates to true

but not true is false

okay

now moving ahead

let's discuss

identity operators in python

all right

so we'll start by assigning a value of

let's say

505 to x

and then in y i'll have

500 plus 5

so which is also 505

so x and y hold

the same value of 505

so i'll print

x comma y

so you can see here both the values are

same 505

for x and y

now i'll use the

logical operator that is

double equal to or equal to equal to

i'll write x equal to equal to y

this will give us true because x and y

hold the

same value of 505

but

let's check with the identity operator

so i'll write x is

y

if i run this

it gives me false

the reason being

x and y both refer to objects whose

value is

505

they are equal but they are not

referencing to the same object

now this you can verify using the id

function in python if i write id of x

this will give me the memory location

that x has you can see this is the

memory location of x

now if i write id of y

there you go so this is a separate

memory location in which

y is holding the value of 505 and hence

x is y is different

and hence it is false

suppose i write x equal to 100 and i

have y equal to 200

if i write x

is not y

this gives us true the reason being

x and y both are holding

different values so x is not y is true

let's see another example this time

we'll define

two lists

so i have a list called a that has value

let's say

5 comma

6 comma

3 comma 7

comma 1 comma let's say 9

and then

i'll have

another list

that will also have the same elements

i'll copy this and i'll paste it here

okay

if i write

c equal to a

and then we'll print

a is c

if i run this it gives us true because

we are assigning

the variable a to c and hence

the memory locations are the same for

both and hence

a c gives us true

what if i write a

is

b

now this gives us false

so here a and b are both less

they are equal but not identical it is

because the interpreter in python

allocates them separately in memory

although they are equal

okay

now let's talk about

membership operators in python i'll give

a comment as

membership operators

okay

let's see i have a list

a that has

the above values five six three seven

one and nine i'll copy this

and i'll paste it here

okay

i have

another list

b that has

different types of elements we have 4

next element is python

then we have

2

comma

7

comma let's say

simply learn

and then i have

nine

i'll run this first so i have my

two lists a and b i have printed them

let's explore how the membership

operator works so

we saw in the slides in and not in our

two membership operators

if i write 5 in a

and run it it returns me true because

you see here

5 is present in a and hence 5 in a will

return true

what if i write 55 in a

this gives us false because you see here

in the list a we don't have

an item 55 in a

so it gives us false

what if i write 4

in

b

this gives me true

you see here in b we have the element 4

so 4 and b is true

one thing i wanted to show you is

what if i write

python

in

b

you see here

it gives us false

though we have

python in our list b

but

the python i'm trying to check

is not present in b the reason being

here

python is written in lowercase

but

what i am checking

python p is

in upper case

so it is case sensitive

and hence this gives me false

let's say

i'll declare a dictionary y

equal to and within curly braces

i'll

give my key a

and i'll assign the value

of india

let's say i have another

key

b

and that has a value let's say usa

now if i check a in y

it gives me true because your key a is

present in y

now what if i check

india

in

by

now this gives me false so here

the membership operator won't work on

the values it only works on keys in a

dictionary

now let me go ahead and change the keys

to numbers i'll give one

that has india and the second key i'll

have two

now

if i change e to one

it will work fine it gives me

india

but if i write usa in y it gives me

false as i said

the membership operator won't work on

the

values it only works on the keys in a

dictionary

cool

now coming to the final section

of our demo

we'll explore about

bitwise operator

okay

so python bitwise and operator returns 1

if both the bits are 1 otherwise it will

return 0. so first let's see

7

ampersand 2.

if i run it

it gives me the value of 2.

so what python does is it will first

convert the numbers 7 and

2 to their binary equivalents that is in

the form of zeros and ones and then it

will perform the bitwise and operation

so

7 ampersand 2 the value is 2

if i write 3 ampersand

5

the value is 1 again it will first

convert 3 and 5 to binary equivalence in

the form of zeros and ones

and then it will perform the and

operation the bitwise and operation

now the python bitwise or operator

returns 1 if any of the bits is 1

if both the bits are 0 it will return 0.

so if i write

10

or

5

it gives me 15 so first it will convert

10 and 5 to binary equivalence and then

it will perform the bitwise or operation

let's see another example i'll write 4

or

i'll run it

so the

bitwise or operation gives us 12 as the

result

in programming languages conditions play

a very crucial role

they help us develop programs that can

satisfy all the business conditions and

perform well

so conditional statements are useful

when we have to decide that a certain

condition or certain part of a code

should run only if the condition is true

so the if statement is an example of

conditional statements

the program will first

evaluate the test condition

and will only execute the code block if

the test conditional expression is true

so here you can see the syntax of

if statement first we have the

if keyword and inside

parenthesis we are going to pass the

condition

and

if this condition evaluates to true then

we go inside the body of the if

statement which is this part of the

syntax

now

while developing a code for a business

problem you might have to use multiple

conditions

so the alif statement is used when we

have to check multiple conditions so

here you can see

if the first test expression evaluates

to false then you have the alif

condition

and

if the lift condition evaluates to true

then we go inside the body of the

elif statement which is this part of the

statement or the syntax that i am

highlighting

next

so sometimes you want to evaluate a

condition and take one path if it is

true

but specify an alternative path if it is

not so this is done with an

else clause

so the else code block will run if the

expression is false

so here you can see if the

condition for the if statement

returns false then we have the body of

the

else statement

and finally

after

all the if alif and else statements have

been executed we will execute if there

are any other statements which are

present outside the if condition now

moving ahead

we will use if else and lf statements to

write a program that will solve a

business problem

so based on the location and total

amount of the items we are going to find

the sipping cost

the locations are a few states in the

united states

in the if statement project we will ask

the user to enter the amount of the

package or the item

and we'll also ask the user to input the

state name

so for the different states we'll define

the conditions using the total amount of

the items and print the shipping cost

so let me take you to my jupyter

notebook where we'll

do this project

okay so i am on my jupyter notebook let

me just rename this

notebook i'll say if

statement

and

project

all right

so

let me go ahead and

give a comment i'll say

package

delivery cost

based on

the location

and

total amount

all right

first and foremost i'll go ahead and

create a variable called total

now this will be

a user input so i'm using the input

function

and here i'll pass the message as enter

the

amount

for

the item

all right

next

i'll assign

another

variable

called state this is also going to be a

user input so i'm using the input

function and i will say

enter the

state name

in

usa

so these are the two

inputs we are asking from the user that

is to pass the

amount for the item and the state in the

usa

all right

now we'll start with our first if

statement i'll write if

state

equaled equal to let's say my first

state name is texas

give a colon

make sure the syntax you are writing is

correct

now i am going to use

another if statement so this becomes a

nested if statement now

i'll write if

total which is my

item amount so i'm checking if total

amount

is

less than or equal to

150

then

i'm going to print

shipping cost

in

texas

is

let's say

30 dollars

all right

now i'll pass my next condition using

elif statement

since i am using multiple conditions so

hence

i am going to use

the alif statement this time i will

write f total

is greater than 150 and

if my total amount is

less than or equal to 250 dollars

then i'll say

print made a spelling mistake this

should be shipping

i'll say print

shipping

cost

in

taxes

is

let's say

20

so usually if your

amount of the item is high then the

sipping cost is low

so here you can see if the total amount

for the package or the item is less than

150 dollars then your shipping cost is

30

but if it is between 150 and 250 your

shipping cost is less which is 20

dollars

then i'll say else

print

shipping

cost

in

texas

is

five dollars

so what basically this means is

if your total is less than or equal to

150 dollars then

the shipping cost would be

30 dollars

if your total amount lies between 150 to

250 dollars your shipping cost is 20

and if the

cost of the item or the package is more

than

250 dollars

the cost is

five dollars

so this is for texas state

now moving ahead

i'll write alif

this time

we'll check the condition for state

let's say florida

i'll

use a colon here and say if

my

total is less than equal to 150 dollars

then we'll print

shipping

cost

in

florida

is

let's say 45 dollars

i'll use the ellipse statement again

i'll say lf

total

if it is

more than 150 dollars and

if it is

less than or equal to 250 dollars

i'll write

print

shipping

cost

in

florida

is

let's say 35

next

i'll

write my else statement i'll say

print

shipping

cost

in

florida

is

let's say 10 dollars

if the cost of the item is more than 250

dollars now one thing to note here is

the shipping cost is different for the

different states in the u.s

all right

now we'll move on to our

next state let me

give a space here

i'll say lf

state equal to equal to let's see we'll

take

virginia now

i'll see if total

is

less than or equal to 150

dollars

will print

shipping

cost

in

virginia

is

let's say twenty three dollars

all right

just scroll down

next i'll write my ellip

statement i'll say lf

total

is

greater than 150 dollars and

total

is

less than equal to 250 dollars

then

we'll

print

just copy this message

paste it here

and we'll see shipping cost in virginia

is

15

next

we'll write our

else statement else

print

i'll paste the message again i'll say

shipping cost in virginia is

five dollars

in case the cost for the

items is more than two hundred and fifty

dollars

now moving to our final state

i'll write another alif statement i'll

say alif state equal to

equal to let's say new jersey

if

total

is less than equal to 150 dollars

then

we'll print

just paste the message here i'll say

shipping cost in

new jersey

is

let's say 40 dollars

now i'll say lf

total

if it is greater than 150 dollars and if

total is less than equal to 250 dollars

will print

just put this within double quotes

and

i'll say shipping cost in

new jersey

is

let's say

ten dollars

i'll say else

my shipping cost

is

free

in case

the

total amount for the items is

more than 250 dollars

all right

finally

we'll have our

else statement where i'm going to print

invalid

state

name

in case the user enters any other state

apart from new jersey virginia florida

and texas

all right

so

we have our small project ready let me

just

run through it

so first we are declaring two variables

total and state and we are taking this

as user input so the user is going to

input the

amount for the item or the amount for

the package and then

the user will input the state

so we have the four states defined here

and we're checking the

shipping cost

for these four states

based on

the

amount for the items

all right

now let me go ahead and run it

so here you can see we have our first

user input enter the amount for the item

let's see

i have my amount as

125

dollars

and the next input is enter the state

name in usa i'll say

let's say florida

if i run this

it gives me the shipping cost in florida

is 45 dollars let's go to the top and

see what we have

now our total was

125 dollars which is

less than 150 and hence

it has printed shipping cost in florida

is 45 dollars

let's

run this again

this time i'll say

let's see my

item costs

255 dollars

in the state let's say new jersey

let's run it

you see here it gives us the message

shipping cost is free now the reason

being if you see

this part of the code

for state new jersey

if the

total

amount for the items is

more than 250 dollars

the shipping cost is free

now let's try for another state

this time we'll see for virginia

let's say my

amount is 190

and my state is

virginia

if i run it it gives me the shipping

cost in virginia is 15

let's check our code

so here i have entered my

item amount to be 190 dollars so it lies

between 150 and 250 dollars and hence it

has printed the message that shipping

cost in virginia is fifteen dollars

now let me enter another

state name that we have not defined

in our code let's say i have

my item amount as

290 dollars

and

the state name

i'll give us let's say colorado

if i run it it gives us the message as

invalid state which is present in the

last part of our code so

since we haven't defined any

shipping cost for colorado it has given

us the message that the state i am

trying to search for is invalid

you can check for

another state or any other country name

anything that is not

part of our

project

let's say i'll enter my amount as

hundred dollars

and this time i'll enter my state name

as

let's say ohio

and we'll run it it again gives us

invalid state

let's try out one last time i have my

package amount as 350 dollars

and let's see

my state is

alaska

again it says invalid state name because

we haven't defined

any condition for

alaska state

so this was a very simple project that

we did using

arif statement we saw how to write

nested if and we saw how to use the alif

and the

else statement

we will start by learning the basics of

loops and look at for loops in python

then we will understand about while

loops in python with its syntax and

coding examples

finally we will see how to write nested

loops in python with hands-on

demonstrations on the jupyter notebook

so let's get started

so what is a for loop in python

a for loop in python is used to iterate

over the items or elements present in a

sequence

the items present in a sequence can be

in the form of a list tuple dictionary

or even a string

a for loop in python uses the range

function to iterate over a specific

number of times

now let's have a look at the syntax of

for loop

so here on the left you can see the

syntax of the for loop so we have the

for

keyword followed by the iterator

variable then we have the in keyword

followed by the sequence it can be a

list you can use the range function it

can be a dictionary or tuple anything

and after that you have your colon

followed by

the statements that you want to execute

in the for loop

and below you have the rest of the code

and here on the right you can see

this is the

flowchart of a for loop so you have

for each item in sequence then we check

the condition if you have reached the

last item

if that is true you exit out of the loop

but if it is false you keep on

running or executing the statements that

are present inside the for loop this

will continue until and unless you have

reached the last item in your sequence

okay

now let's head over to our jupyter

notebook where we'll

see for loop in detail

and we'll explore a lot of code examples

okay so here i am on my jupiter notebook

let's start by writing a simple for loop

suppose i have a variable

say s

and it has a value which is a string

let's say simply learn

okay

now

the way to write a for loop is i'll say

for

i which is my iterator variable it can

be any valid variable name in python

in

my variable that is s

so here s becomes my sequence

i'll say print

i

so what this for loop is going to do is

it will iterate over all the characters

that are present in my string and print

them one by one

let me run it by hitting shift enter

you see here using this for loop we have

i traded over

all the letters that were present in my

string that is simply learn and we have

printed them one by one

okay

now

the print function in python provides a

parameter called end so by default

the value of the parameter is

backslash n that is the newline

character now you can end a print

statement with any character or string

using this parameter which is end

let me show you what i

meant so i'll again

have my same string simply loan

i'll say for i in

my variable

or my sequence s

i'll say print i

comma

then i'll use my end parameter equal to

and

my end parameter will have a value of

asterisk

now let me run this you can see here

this is sort of a pattern that we have

printed

so between each letter in my

string simply learn we have an asterisk

okay

moving ahead

let's see how to

use

for loop

in a list

all right

i'll declare a list called

programming

and this list will contain

a few programming languages let's say we

have java and then

the next item we have in the list is

python

next we have ruby and then

we'll have html

okay

so

i'm going to print

all the

individual items that are present in my

list using the for loop

so i'll use the same syntax i'll write

for

this time i'll use my iterator variable

name as iter which means iterator

for iterator or iter in

my sequence which is programming

i'll say print

iter

let's run it you see here we have

printed all the items in my list one by

one

java python ruby and html

all right

now let's see

an example how you can find the average

of a list of numbers using for loop so

i'll give a

comment saying find the

average of a

list of numbers

okay

so here

first of all we'll declare a

list of numbers with variable list

underscore num equal to

it will have a few numbers let's say 20

25 10 50 and

40.

let's make it 45

now to find the average of a list of

numbers

first i'll declare a

variable called sum that will have

a value of zero so we have initialized

the sum variable to zero

then i'll start my for loop for i

in

my sequence that is list underscore num

which is

this variable

give a colon i'll write sum

equal to

sum plus i

so here

just give a space to make it more

readable

so i'm adding

all the numbers in my list and we are

storing the result in the variable sum

then we'll say

print

sum

equal to

i'll pass in my variable that is sum

then i'll say print

average

equal to

now our average will be

my variable sum divided by

the length

of my

list that has all the numbers

let's run this you see here

so a total sum of all the numbers

present inside the list is 150 and the

average of

all these numbers is 30 so 150 divided

by 5 is 30

all right

let's see how you can use a for loop

using a tuple

so let's declare a variable called num

is going to a tuple of numbers

and we have 30 45 60 50 and let's say 70

as the numbers inside the tuple

i'll say sum equal to zero

then we'll have our for loop for i in

my sequence that is num

i'll say

sum equal to

sum plus i

so here we are just adding the values

that are present inside the tuple

i'll say print sum

so here you can see we have

printed

all the values present inside the tuple

one below the other now if i shift my

print statement to here

you can see here this is my

sum of all the numbers that are present

inside the tuple

so make sure you have

the current

indentation

now let's see how you can use the range

function in python

okay

so you can use the range function to

iterate over a range of values

or numbers

using a for loop

the way to do is i'll say for i in

my function range

i'll give my first index at 1 and my

second index at

or my end index at 10

so this will go from 1 till

9 and exclude the 10th index

i'll say print i

you see here

for i equal to range 1 to 10 we have

printed all the numbers starting from 1

till 9. so

the last index that is 10 is

exclusive in the range function

now in the range function you can also

give a third parameter that stands for

step

so that you can skip a few steps and

print the next value let me show you

what i mean

say i write for i in

range

0 which is my starting index

10 which is my end index

and i'll have a step size of 2

give a colon

i'll say

print

display

values

with

a

step

size of

2.

give a comma here and my variable that

is i let's print it

there you go

so we have printed

the values with a

gap of two so it starts from zero then

we are jumping two steps and then we are

printing two then again two steps we

have four six and eight so we are

skipping

one value

and printing the next value

in my sequence

ranging from zero to ten

all right

now

let's write a program to print

a table of a given number

so i'll give a comment as

program

to

print

table of a

given

number

all right

so i'll pass my

variable n

which is going to be a user input so i'm

using the in function and inside the in

function i'll use the input function to

take the user input

i'll give my message as enter the

number

i'll say for

i in

range

from 1 to

11

i'll say

multiply which is mul here

and

asterisk i

so basically what i'm doing here is

i'll take a user input of the number

let's say we want to print the table of

5

so from

1

till 10 will have the product of the

numbers

let me print it

i'll say print

n

comma

within double quotes i'll give my

asterisks

comma

i

comma

within double quotes i'll say equal to

and then we'll have our

variable mul

let's run this

enter the number i'll give 5 and hit

enter

there you go

so here we have the multiplication table

of

my number 5 so you see

5 into 1 which is 5 5 into 2 is 10

then we have 5 into 7 35 5 into 9 is 45

then

our last index which ends at 10 so we

have 5 into

10 that is 50

all right

this is how you can create a simple

multiplication table using for loop in

python

now we can also use the range function

with a sequence of items

the len function can be combined with

the range function to iterate through a

sequence using indexing

i'll show you

an example here let's say we have a list

called list 2

and here we have

a list of programming languages let's

say

c plus you can either use a single quote

or a double quote to represent the

text

values in a list

the next programming language i have is

java

then let's say i have python and we have

r

okay

so i can write for i in

range

here i can use the length function

and i'll say

list

2

give a colon

then we'll

print hello

and i'll say

list 2 of i

so what it does is

my iterator will iterate over

the list of programming languages i have

here

and it will keep on iterating

till

the length of the list

and then i am printing my message as

hello

and it will take each item

from the list using the index number

if i run it you can see here it says

hello c plus plus hello java hello

python and hello r

cool

now let's see how you can use

nested for loops in python

i'll say nested for loop

as my comment

let's see i have a

list

of company names

my first company i have in my list is

google

let's say apple

pwc

and then we have

uber

so here i'll write for i in

companies

i'll say print

we

will

display

each

letter

of

i'll say plus i

now i'll use my second for loop sync for

letter in i

will print the letter

let's run it and see our result

there you go

so here we have used

two for loops so that becomes a nested

for loop we have my outer for loop and

then

we have our

inner for loop so in the outer for loop

we are just printing

the

name of the company so here we see we

will display each letter of

plus i which stands for

my company name google so you can see

below we have

displayed each letter of google using

the

inner for loop similarly we have

for apple you can see a p p l e we have

pwc and then we have uber

so this is how you can use

multiple for loops

in python

now let's see how you can use a for loop

with else clause

so i'll give a comment for loop with

else clause

so i'll write for i in

range

0 comma 10 comma i'll give a step size

of 3.

i'll say print

i

and after this

python gives you the flexibility to use

an else clause

after the for loop so i'll write

else print

the

loop has

completed

execution

so this is my message

that we are going to print after we have

printed all the

elements

that are present inside this range

function

let's run it you can see here we have

printed

the value starting from 0 with a step

size of 3 so we have 0 3 6 until 9

and then

after that we have our else block

printed

which has the message the loop has

completed execution

cool now let me show you

two more

important feature that you can use while

writing a for loop one is called the

break statement the other one is called

the continue statement

so in python you can break the for loop

and end it before it has actually run

all the elements in the i table using

the break statement

so let me show you a simple example if i

write for

just give a space here

i in

range

let's say from 1 to 10

i'll use an if condition

saying if i equal to equal to 6

then

break and come out of the loop

next we'll print i

so here what we are doing essentially is

we are iterating over

all the values from 1 to 10 and whenever

the i value becomes 6 we come out of the

loop and print

all the values we have iterated so far

let me run it and we'll see the result

the yuko so here our i value started

from 1

we printed 1 2 3 4 5

and then

our i value reached 6 then we use the

break statement to come out of the loop

all right

now

you can also skip the execution of

further statements in the for loop

during the titration using the continue

statement in python

so when a continue statement is executed

the for loop continues with the

execution of the next element in the i

table

it does not complete all the statements

in the for loop body

so again we'll

give a comment

say continue

okay

so i'll write for i in

range

again from 1 to 10

give a colon i'll say if

my i value

is equal to equal to 6

then i'll say continue

then we'll print

i

let me run it and we'll see the result

okay so if you notice this

output so we have printed values from 1

to 5

and when my i value became 6

we skipped printing 6 and we

moved on to the next element in the

iterable which was 7 then we printed 8

and 9.

so this is how you can use the break and

continue statements in python

all right

now we'll see a program to display the

total goals a player has scored

so here we are going to iterate over a

dictionary

so i'll give a comment program to

display

the

total goals

clear has code

all right

first of all

i'll declare a variable saying clear

name

and let's say we have the player name as

carmelo

all right

i'll declare a

dictionary called ghouls

and within

curly braces i'll have

my first

clear name addition

let's see edition has scored

14 goals then we have let's say

burnett so burnett is my key here and

then we'll have

value in terms of goals let's say three

and then we have our third player let's

say carmelo

and carmelo has scored let's say seven

goals

now i'm going to write my for loop so

i'll write for

my i table name here is player

in

my sequence name is goals so i'll say

goals

i'm going to check if

my

player

is

equal to equal to

player name

i'll say print

the goals scored by the player

so i'll

pass my dictionary name and within

square brackets

i'll say

clear

let's

use the break statement

and then

i'll say

else

will print

my message would be

no player with

that name

found

let's run and see the result

all right so here

what we did was initially i declared a

variable called player name that had the

value carmelo

and since carmelo was present inside my

dictionary

named goals you can see here we have

carmelo who had scored seven goals

so i i traded over

my sequence goals and i checked if my

that is player is equal to equal to the

player name which is carmelo since this

carmelo is present inside my dictionary

name so we printed the goals that were

scored by carmelo that is 7.

now let's say i change this player name

to

we have let's say messi

now since messi is not present inside my

dictionary goals if i run this

it will print no player with that name

found the reason being message is not

present inside

my dictionary called goals

cool

now

we'll see two more

examples

this time

we are going to

print the cube of

numbers using for loop

all right

so first of all i'll declare a list

which will have a list of numbers let's

say 2 5

7 4 8 and let's say 6.

then

i'll pass in a

empty list so i'll declare within

empty square brackets

i'll say for i in

my sequence name that is num

i'm going to use my empty list cube and

then followed by the append function

and inside the append function we'll

have our

cubes of the number so i'll write i

i'll use the double asterisk operator

and then i'll say three

after that we are going to print

my

list name that is cube

let's run it

there you go

so you can see here

first we have

the list of the numbers here

and then

we have printed the

cubes of these numbers in a pattern

let's say

bring this print statement here and i'll

run it again

now this is much more readable you have

2 cube is 8 5 cube is 125 7 cube is

3

43 then 4 cube is 64 8 cube is 512 6

cube is 216

all right

now coming to

the last example in our demo section of

this

for loops in python video

will

write

a program to print a pattern

i'll say pattern printing

all right

so we are going to print

a right angle triangle

for that i am going to take

my first variable called n which is

going to be

a user input to enter the number of rows

so using the input function

i am passing the message

enter the

number of

rows

i'll say for i in

range

0 till my user input n

[Music]

give a colon

i'll use my

inner for loop

this is

going to be the number of columns so

i'll say for j in

range

0

comma i plus 1

give a colon

and

i'll print

my star pattern so i'm using asterix

and i'll use my end parameter

i'll have my double quotations

and then

we'll say

print

the pattern

so here what i am doing is i am taking

the number of rows from the user

and i'm iterating

from 0 till n which is my user input and

then

we are

assigning another for loop for the

number of rows so that ranges from 0

till i plus 1

then i'm printing my star

let's run it and see the output

let's say i'll enter the number of rows

as 6.

if i hit enter you can see here we have

our right angle triangle printed here

so initially

my

i value is

0

so here

my j value becomes from 0 till 1 so we

have just 1 star printed

in the next iteration my i value becomes

1

so from

0 to 1 plus 1 that is 2 we have 2 stars

printed the next iteration my i value

becomes two so two plus one is three

again so we have three columns here so

three stars printed so on and so forth

all right if getting your learning

started is half the battle what if you

could do that for free visit scale up by

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so what is a while loop in python

a while loop specifies a condition or a

block of code that is to be executed

until the condition evaluates to false

or the loop is explicitly ended with a

break statement

moving on to the next slide

so here you can see the syntax of a

while loop

so a while loop is defined using the

while keyword and then you have the

expression followed by a colon

after that you have the statements

inside the block

the statements are executed until the

condition evaluates to false

now on the right side you can see the

flowchart to show

all the steps

to execute a while loop so you can see

here we have the test expression if the

test expression evaluates to true then

we execute the statements that are

present inside the while block

but if the condition is false we will

exit out of the while loop

now before i move on

i have a question for you

so here is a python quiz question

i want you to tell me the output of the

below code so this is regarding a list

i have declared a list called alpha that

has d

f and c as its elements then i am saying

alpha plus equal to ka which is again a

string since it is within the single

quotes then i am printing the list

now you need to tell me what is the

right answer you have four options here

a b c and d the first option is d comma

f comma c comma k a combined

then we have k a in the beginning of the

list

followed by dfc

the third option or the c option is d f

c k a k being

individual elements

and the last option the d option is k a

d f c

please go ahead and solve this question

and put your answers in the comment

section of the video

we'll be more than happy to know from

you

all right

now let's

go ahead and start with our demo

so here i am on my jupyter notebook let

me

rename my file i'll say

while looping python

demo

okay

so

let me start by writing a simple while

loop i'll declare a variable called i

equal to 0

then i'll start with my

while loop

i'll write my while keyword

and this will run till my i is less than

10 let's say

i'll give a colon

and if i hit enter it will come to the

next line you can see the indentation

here which is being maintained i'll say

i equal to

i plus 1 so i am incrementing my i value

then i'll say print

i

and i'll use my end parameter

and i'll say end

within

single quotes i'll say hash and give a

space

then let me say print again

so here my while loop will run until my

i value is less than 10

so we are continuously incrementing the

i value and printing the i value

let me run it there you go you can see

the result here

we have printed the i values starting

from

1 till 10

and after that

we have come out of the loop

and you can see the

hash symbol being used here because we

used our end parameter as has

so by default it is a new line character

but we have explicitly defined our

end parameter as has followed by a space

cool

now let's move on to our next example in

this video on while loop

i'll define a variable called count

and i'll assign a value 0

i'll say while

my count is

less than equal to 5 i'll give a colon

come to the next line and i'll print

the

condition

is

true

and then i'll say

count

equal to

count

plus 1

and then i'll say

print

end of loop

let's run and see our result

you can see here we have printed our

message the condition is true five times

because

our expression is being evaluated five

times here

in the sixth time our count is no more

less than equal to 5 so we

end the loop and here you can see the

message end of loop

cool

now moving ahead

you can also use

the break statement

in a while loop let me show you how to

do it

i'll say while true

so i am

declaring my

while loop to be true

and i'll say

please

type

your

name

and i'm going to

take my

name as input from the user so i am

specifying the

input

function

i am going to check if my name is equal

to equal to let's say

gilly

then i should give a colon here

i'll break out of the loop

and then we'll

print

thank you

you

typed

the

correct name

all right

so what i'm doing here is

i'm going to run this loop till the user

enters the correct name so i have

declared my name as gilly if you enter

any other name apart from gili

this while loop will

continue to run and execute

run it okay

so here it says please enter your name

i'll let's say say john

if i run it

it is again asking me please enter your

name let's say this time i'll say ami

you can see here it is again asking for

the

name so i'll enter my name let's say

hopkins

again

our entered

user name doesn't match

the name that we have provided in the

code let's say this time i'll say gilly

if i hit enter you can see we have our

message thank you you typed the correct

name

okay

now moving on to the next example we

will see how to find the least common

multiple of 4 and seven

so i'll give a comment as

lcm of

four and seven

now you would know

it is 28 but we are going to find out

with the help of

a python while loop so first i'll

declare a variable x equal to 0

i'll say while

my expression is true

i'm going to increment my x value to 1

i'll say x

plus equal to 1

this means x equal to x plus 1

i'm going to use

an if statement and say if not

and here we'll pass the condition

x

percentage 4 or modulo 4

or

x

percentage 7

then i'll say break

finally we'll

print our message saying x

comma

and i'll say is

divisible

by

four and

seven

say both four and seven

okay

so what i am doing here is

i am taking my expression while true

i'm incrementing the value of x

each time and checking if

this is true or not

now at the first instance when my number

x is divisible by both 4 and 7 i'm

coming out of the loop and we are going

to print this now let's see

what's the answer there you go you can

see here 28 is divisible by both

4 and 7 and hence the lcm of 4 and 7 is

28.

so this is the least

number which is divisible by 4 and 7.

all right

now you can also use the continue

statement

how you use the break statement to

come out of the loop you can also use

the continue statement to continue

running the loop

so i'll say

i equal to 0 while i is less than 10

so this is my expression my loop is

going to run until i is less than 10 i

am going to increment the value of i

i'll say i plus equal to 1

if

let's say i set my condition if i equal

to equal to let's say 6

then i'll say

continue my execution and skip the

current step where

i value becomes six

then i'll say print i

let's run it and see the result

okay you can see here we have printed

one two three four five and here you can

see we have skipped the execution where

i value became 6 and continued with the

next iteration 7 8 9 and 10.

so this is how you can use the continue

statement and the break statement in a

while loop

all right

now moving ahead you can also use the

else statement in a while loop now let

me show you how to do it

i'll say i equal to

1 then i'll write while i is less than

let's say 5

i'll say print i

then i am going to increment the value

to

i plus equal to 1.

now here you can use the

else statement and say print

i

is

not

less than

5

let's run it you can see here

we

ran our loop until i value was less than

5 so we printed 1 2 3 and 4

when i value became 5

we printed

i value is not less than 5.

cool

now moving ahead

so you can

use inbuilt functions inside a while

loop let me show you

how to use the

pop function and remove the elements in

a list using a while loop

so i'll declare a list

of numbers let's say 1 comma 2 comma 3 4

and we have 5 so these are the 5

elements that are present inside list a

i'll say while a

so i'm iterating over all the elements

in my list

i'm going to say print a dot i'll use

the pop function

so

what pop does is it is going to remove

the elements

from the end of a list

then i'll say else

print

there

are

no elements

left

in the list

all right

let's run it and see the result you can

see here we are removing

the elements one by one from the end of

the list so first we popped out five

then four three two and one and after

that we had no more elements left in the

list so we printed there are no elements

left in the list

okay

now the next program we will take

numbers as input from the user and

calculate the average

as long as the user enters a positive

number

so i'll give a comment

average of

positive numbers

cool

okay

so i'll start my program i'll declare a

variable called num

which has a value 0

i'll declare a variable called count

which also has a value 0

then i have sum

which has a value of 0

i'll write while

my

number is greater than equal to 0 so

this condition

is for accepting only positive numbers

i'll say num equal to

i'm going to take the positive numbers

from the user

so i'll

pass an input function i'll say enter

any

positive

number

then i'm going to say if

my number is greater than 0

i'll say

count equal to

count plus 1

let's make this

greater than equal to 0

then i'll say sum

equal to

sum plus

my number

so here i am keeping track of the

numbers that we have

entered and here we are calculating this

sum that is the cumulative sum

then i'll say

avg

which is to find the average

i'll say sum divided by my variable that

is count

then

i'm going to print

total

i'll say total

sum of

numbers

give a colon

followed by a space

give a comma i'll say sum

then

i'll

say

average

give a colon

followed by a space

and i'll pass in the variable avg

alright

so here i have my

program ready where we are using a while

loop and

an if statement

to

take numbers as input from the user and

calculate the average as long as the

user enters a positive number

so let me run it

okay it says enter a positive number

i'll say let's say five

again it's asking for a positive number

i'll say

seven

let's say 10

and this time i'm going to enter a

negative number so i'll say minus

6.

if i run it you can see here

the total sum of numbers

5 plus 7 plus 10 is 22

and the average is 22 divided by 3 which

is 7.33

all right

let me give a space here for more

readability

we are going to try it again

i'll say 40

50

30

and

let's say 100

this time i'll enter a negative number

let's say minus 90.

okay so you can see here

i have entered four positive numbers 40

50 30 and 100

so the sum of numbers is 220

and the average is 40 plus 50 plus 30

plus 100 which is 220 divided by 4 which

is 55

cool

now moving on to the last

demo in this while loop with python

tutorial

so here we are going to

guess a number so the user is going to

give a number between a certain range

and based on a random input generated

from the program

we are going to guess

the random number

all right

so for that

i am going to start by importing my

library called

random i am going to

say n

equal to

random

dot

rand int which is a function to generate

random integers i want to generate

between 1

and 100

let's go ahead and print that number n

then

i'll use a variable called guess

which is going to be

a user input

so i'll say input which is my function

and i'll give the message enter an

integer

between

1 to let's say 100

okay

then i'll start my while loop saying

while

n

not equal to

my

variable that is

guess

i'll say if

my

guest number is less than n

i'll print the

message as

your

guess

is let's say low

then again i'll say guess equal to

i'll take the

user input

just copy this message

and we'll print it here

okay

now

i'll say

alif

if my

guess is

more than my random integer

will print i'll just copy

this we are going to print

your guesses

let's say hi

then we are again going to

ask the

user

to

guess a number between

1 to 100

and after that i'll say

else

will print

you

guessed it correctly

then we'll

break out of the loop

and finally i'll just

print it

okay

so what we are doing in this game is

before that let me just give a

comment as guessing game in python

so first of all we are generating a

random integer using the library called

random so the integer

will lie between one and hundred

i am going to print that integer

after that i am taking a user input

so i am asking the user to enter an

integer between 1 to 100 and i am

checking if my

random integer

is not equal to my

user input that is guess

and if that guess

is less than my random integer i am

going to print your guess is low

then i am again asking the user to input

an integer between 100

then i'm saying if the

guest

value is more than the generated random

integer

will print your guesses high

then after that i'm again asking the

user to input an integer

and in case

the random integer

matches with the

guest number will print you guessed it

correctly

all right let's try this out

okay so here you can see

so my program generated a random integer

48 that lies between 100

so

our loop will only stop executing when

we

enter our

number as 48

otherwise it will keep on running and

asking you

to enter an integer

let's say i enter

50.

you see here

your guest value that is 50 is

more than

the random integer 48 so we have the

message

your guess is high

let's say i'll say 30.

this time my guess is low you can see it

here

let's see i'll

take my

number as

300. you see here

this time my guess is high which is more

than 48

but if i say

my user input to be 48 and if i

hit

enter there you go we have our message

printed you guessed it correctly

all right

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what is a nested loop

python programming language allows you

to use one loop inside another loop

this is known as a nested loop it is

present inside the body of the outer

loop

the inner or outer loop can be a for

loop or a while loop

the outer for loop can contain a while

loop or an outer while loop can contain

a for loop inside it in python nested

loops the outer loop can have more than

one inner loop there is no limitation on

the chaining of loops

now you can see on your screens the

basic syntax of writing a nested loop in

python

you have the outer loop followed by the

inner loop and the statements inside the

inner loop and finally you have the

statements of the outer loop the last

three lines consist of the body of the

outer loop

now talking about the various ways of

writing

nested loops in python

so with python you can write a for loop

inside

another for loop or

you can have a while loop declared

inside another while loop you can see it

here

so using python you can use both for

loops and while loops together

the outer loop can be a for loop and the

inner loop can be a while loop you can

also write nested loops having a while

loop outside and for loop inside so now

that you have learnt about the basics of

nested loops let's look at an example of

printing patterns

so in the code here

we have used

two for loops to get our

right angle triangle containing

asterisks or stars

so

we have declared rho equal to 7 which

means we need seven rows to be printed

you can count it here these are seven

rows

hence we have defined it as

rho equal to seven

now the outer for loop ensures we have a

total of seven rows

so we have defined a range

from

1 to row plus 1 that is 8. now the inner

loop is the total number of columns in

each row

so for each iteration of the outer loop

the

columns count gets incremented by 1.

so for the first titration of the outer

loop the column count is 1 in the next

iteration it is 2 and so on

the inner loop iteration is equal to the

count of the columns and for each

iteration

in an inner loop we print a star

so for the first iteration when i value

is 0 it will first print a blank

when i value becomes 1 then your j range

becomes 1 comma 1 plus 1 which is 2 so

it will print

1 star here followed by a space

when i value becomes 2 your j range

becomes 1 comma 3 so it will print

2 stars

then again when i value becomes 3 your

range becomes one comma four so it will

print three stars so so on and so forth

now let's see

when you should use a nested loop in

python so nested loops are mostly used

to work with multi-dimensional data

structures such as printing

two-dimensional arrays

i treating a list that contains a nested

list etc

you can use python nested loops to print

different star or number patterns as

well now let's

head to our jupyter notebook to do some

practical hands-on demonstrations to

understand nested loops in python better

okay you can see here i am on my jupyter

notebook first of all i'll

rename my

notebook as nested loops

in

python demo

click on rename

all right

now let's see our first example

so here

we are going to print the items in a

list one by one but each letter in an

item should be separated by the at sign

which is basically the add the rate

symbol that you use in your email ids

all right

and for

the first demo we'll be using nested for

loop

so let's start

i'll create a list

which will

have the names of the

fruits

let's say we have

mango

we'll give a comma

let's say i have apple

grapes

and let's say we have banana

all right

now i'll

create my outer loop so i'll say

for

fruit

now this variable can be any valid

python variable this is basically known

as an iterator on an iterator variable

so i'll say for fruit

in

my list which is list underscore fruits

that i have declared in my

first line

i'll give a

colon

and then

declare my inner loop i'll say for i in

my variable or the iterator that i had

declared in the previous line which is

fruit

i'll say

print

i

and then

i'll use

the end parameter that will have

the add sign

and then

i'll print

a blank

so this is my first

nested loop that i have created so i

want to i trade through all the items

present in my list underscore

fruits

variable

and for each item

in the list i want to make sure

that each letter in an item should be

separated with the add sign

so let me go ahead and print it so that

you can see the result the hugo

so here you can see we have printed the

different items that were present in my

list which was list underscore fruits

and

for each item

the letters

in the item have been separated by the

add sign you can see here

all right

if you want you can change this symbol

to let's say

star

if i print it

you can see the difference in the result

now we'll see our second example where

we are going to print the values of

items

in two lists together

so let me create a

list called

color that will

have the different colors such as red

we have green

and let's say blue

and the next list i'm going to create

will have three items

the first item is

apple

then we have

veggies

and then we have

shirt

now

now to print the values of the items in

these two lists together i'm going to

use two for loops again

so i'll say for

my iterator variable let's say x in

my

first list which is color

so i've declared my outer loop and now

i'll say for

another iterator variable let's say y in

my second list items

i'm going to print

x

comma y

and after that

will

print a space

so first of all

my outer for loop will

iterate through the items

that are present inside

color list

and for each color we are going to

iterate through

the values that are present inside

items list

now let me go ahead and print it

you can see it here

first we are printing red apple red

veggies and red shirt then we have green

apple green veggies and green shirt

for scroll down you can see blue apple

blue veggies and blue shirt

okay

now coming to our third example

here we are going to print a right angle

triangle with

10 rows we have seen a similar example

in the slice where there were seven rows

now we are going to print a right angle

triangle with 10 rows

i'll give a comment

let's say

print

right triangle

okay

so i'll start my

for loop i'll say for

any

iterator variable let's say i in

range

i'll pass my range as 11 so it will

go from

0 to

10

then i'll say for

j

in

range i

so this will

take the number of columns

i'll say print

within double quotes i'll give my star

because i want to print a star pattern

for the triangle

and i'll end with a

space

then i'll say

print

blank

so there won't be any space between

the different rows

now let's print the result there you go

so here you can see we have a right

angle triangle of 10 rows you can count

the

number of rows and also we have the

number of columns as 10.

so when i value is

one your g range also becomes one so we

print one star then when i value is two

we are going to print two stars when i

value is three we are going to print 3

stars

and

we are using the end parameter as a

space

ok

now let's go ahead and

print a right angle triangle using a

nested while loop so unlike the for loop

the while loop

doesn't have a pre-compiled iterable

sequence

the while loop keeps executing the code

until the expression evaluates to true

so

i'll

start with the

variable i equal to 11 because i want to

print

10 rows

that will contain

my star pattern

now i'll declare my first while loop

i'll say while i is

greater than 0

so my loop will continue

until i is greater than 0

i'll see z equal to 11

then i'll use my inner

while loop i'll say while

j is greater than

i

will

print

star

and i'll use my

end parameter as space again

then we are going to decrement

j by

1

i'll come out of the inner while loop

and i'll say i equal to i minus 1 so we

are also decrementing

the first

variable i by one and now i'll say print

okay

so let me run this

you can see it here we have the same

pattern printed

earlier we saw this using

two for loops and now we have created

the same pattern using

two while loops

all right

now

moving to our

next example where we'll see how to

append

tool list so first of all i am going to

declare

list 1 and list 2

and we are going to append the elements

of both the list into an

empty list called result

so i'll give a comment

append

two

lists

okay

so first i'll declare my

list one

now these are

list of numbers let's say i have

10 25 and 30 as my

elements in the first list

and then i'll declare my second list

which will have let's say 60

15 and 50.

okay

now i'll declare

an empty list called result

and after that i'm going to start my

outer for loop i'll say for i in

my list 1

then i'll say for

j

in

list

2

i'll say result which is my

empty list that i have declared

then i'm going to use the append

function that is

inbuilt in python

i'll say i plus

j

so this will make sure will append

the values from both the list into

my

empty list which is result

then i'll say

print

result

okay let's run it there you go

so what we are doing here is i am adding

each element in list 1 with all the

elements in list 2. if you see here 10

plus 60 is 70 then we have 10 plus 15

which is 25 10 plus 50 is 60. similarly

25 plus 60 is 85

25 plus 15 is 40 then

25 plus

50 is 75 and similarly for 30 plus 60 30

plus 15 and 30 plus 50

great

now

moving to our next example

we are going to see how you can multiply

the values in

two lists

so i'll give a comment

saying multiplying

two lists

i'll declare my first list which is list

one

with 2 comma 4 and let's say 6

then i'll have my list 2

with the

same elements 2 4 and 6.

start my outer for loop for i in list 1

then i'll say

for

j

in

list

2

i'm going to

show you another feature that you can

use while implementing

nested lists

that is to use

continue or break

so i'll say if i equal equal to z then

i'll continue

after that we are going to print

the value of

i

followed by

the

asterisk

then

the value of g

will give a comma

then within

single quotes i'll say equal to

then i'll give the operation i

multiplied by

j

so this is how you can multiply

the elements in two lists

so i've declared my list one my list two

then i'm using two for loops and

whenever my i value is equal to equal to

j will skip that step and move on to the

next iteration

let me run it and show you the result

so if you notice here

i haven't

multiplied

2

and 2

the reason being i have used this

if condition

whenever i was equal to j we continued

with the next iteration similarly there

is no

output for

4 multiplied by 4 or 6 multiplied by 6

but for the remaining we have our result

2 multiplied by 4 is 8 2 multiplied by 6

is 12 similarly

4 multiplied by 2 is 8 4 multiplied by 6

is 24

6 multiplied by 2 is 12 and 6 multiplied

by 4 is

24.

so

continue and break our two statements

that you can use inside nested loops in

python

okay

now

we are going to

write another nested loop using a while

loop and a for loop to check whether a

number is a perfect number or not

so basically in this program we are

going to print the perfect numbers

between 100

now a perfect number is a positive

integer that is equal to the

sum of its proper divisors

so the smallest perfect number is 6

which is the sum of 1 2 and 3 so these

are the

perfect divisors of or proper divisions

of 6 1 2 and 3. if you add them the

value is 6 another example is 28

the proper divisors of 28 are 1

then you have 2

4

7 and 14 if you add them the value is

28.

so here we will iterate the first 100

numbers using a while loop so for each

iteration of the outer while loop the

inner for loop executes from 1 up to the

current outer number to check if the

current number is a perfect number or

not

okay

so i'll give a comment

saying

perfect number

cool

so i'll first declare a variable called

a which will have a value of one then

i'll say

while

my a is

less than equal to

100

then i'll declare another variable

called y underscore sum which will

have the value of 0

after that i'll pass in my

inner loop which is the

for loop i'll say for

i in

range 1 comma a

i'll say if

a

mod

i is equal to equal to 0

then we'll say y underscore

sum

equal to

y underscore sum

plus i

then i'm going to say if

my

y underscore sum value is equal to equal

to

my e value then it's a perfect number

so i'm going to use a print statement

saying print

perfect

number

give a colon

then i'll give a comma and

print my variable e

and finally we are going to increment

the value of e to 1.

now let's run it

you can see it here

between 100 we have two perfect numbers

as i mentioned earlier 6 and 28

okay

now coming to the

final example in our demo on nested

loops in python

here we are going to print each element

in the list five times

so

i'll first declare my list let's say

fruits

which has

apple then we have

orange

and let's see we have kiwi

so i'll say for

a nitrater

fruit in

fruits

i'll declare a variable called count and

initialize it to 0

then i'm going to use a while loop

saying while count is

less than 6 since i want to print the

items in the list 5 times

then i'll say

print

fruit

and i'll use my end parameter as a space

then we are going to increment count by

1

and finally i'll print it

let's run it you can see it here i

printed each element in my list fruits

five times you can see it here okay so

i'm on my jupyter notebook first of all

let's rename our notebook to

looping techniques

okay

i'll just increase the

size

all right

okay

so let's see how you can arrange the

values in a list using for loops with

python sorted function

so i'll create a variable called num

and

i'll assign a list let's say it has

values 2 5

10

4

i'm taking just random values

let's say 36

50

and 49

so this is my list now i want to arrange

the

items in this list

in either ascending or descending order

so for that i can use a for loop i'll

say for i which is my iterator variable

in

and after this i'm going to use the

python sorted function

and inside the function i will pass in

my variable which is num

then i'll give a colon and say print i

so let's

hit shift enter to

run it

okay

you can see here

so python by default

has sorted the elements in the list in

ascending order so we have 2 4 5 10 10

36 49 50 and

50.

now let's learn how you can sort the

values in a list using a for loop in

descending order

so

i'll just

copy my above cell of code

we'll paste it here it will help

save us some time

so i'll say for i

in sorted

i've given my variable num

after this

i am going to pass in another parameter

called reverse

equal to

i'll say true

now reverse equal to true will make sure

python will sort the list in descending

order

if i run it

you can see the difference we have

sorted the elements in the list num in

descending order now so we have 50 50 49

36 10 5 4 and 2.

okay so this is one of the

techniques that you can use

to sort the elements in a list using a

for loop

now similarly you can also sort string

elements alphabetically in a list and

ascending or descending order

so for that i'll create a variable

called players let me just scroll down

then i'll create a list

which will have the

names of football players let's say we

have messi

then

let's say we have

ronaldo

then we have

salah

and then we have let's say harry

okay

i'm going to say for i

in

my function sorted

i'll say

i'll give a comma

and again use reverse equal to true

so

this is going to sort

the

items in my list players in descending

order of

the alphabets

then i will give a colon and say

print i

let me run it you can see here

the names of the different football

players have been sorted in descending

order of

alphabet so we have s appearing first

then r m and h so salah ronaldo messi

and harry

all right now let's move ahead

now we are going to create a dictionary

of

key value pairs and sort it

so i'll create a dictionary called d

which will have

a few key value pairs so my first key is

f and the value is let's say 1

then my second key let's say is b

and the value is 4

i'll give a comma

my next key is a and the value is let's

say 3

after that my next key is e

and the value is let's say 9

and finally we have our last key which

is c and the value is 2.

now to sort this dictionary i'll say for

i

in

sorted

i'm going to use the

items method i'll say sorted d dot items

and then we'll print i

let me run it and show you the result

you can see it here

our dictionary has been sorted in

ascending order of the dictionary keys

so we have a b

then c there is no d here

after that we have e and then f

cool

now you can also sort the

keys and values separately let me just

copy this and i'll show you

i'll paste it here

and instead of d dot items i'll just say

d dot keys

if i run it

you can see here we have

sorted only the

keys in my dictionary

now to sort the values instead of items

you can just write values

and here you can see we have

sorted the values in the dictionary d in

ascending order again so we have 1 2 3 4

and 9.

all right

now

we will understand how to use the

reverse function in loops to reverse the

items in a list

so i'll again

create my

list called players which will have

messy

let's say again the next player is

ronaldo

and then we have

salah and then we have harry

okay

now to

reverse the elements in this list called

players i'll say for

i in

then i'll use the reversed function and

pass in my list called players

give a colon and then say print i

let's run it

here you can see

we have reversed the

elements in my list called players so we

have harry first then salah ronaldo and

messi in the end

cool

now moving ahead

we'll see how to use the filter function

in loop and filter specific elements in

a list based on some conditions now to

give the condition we'll be using an

anonymous function in python that is

often called as the lambda function

to do this

i am going to create a list

called animals

i'll give my square brackets

and inside these square brackets

i'm going to

pass in the elements in the form of a

dictionary

so to pass in a dictionary we need to

have key value peers

so my first key is name

let's see

my animal is

dogs

i'll give a comma

then my next key is the age let's say

dog's age is 11

so this is my first

list element which has been passed in

the form of a dictionary

i'll create another curly bracket and

we'll have the same keys

this time let's say

my animal is lion

let's make it dog instead of dogs

okay

give a comma and then say

age

let's say the age of the line is 30

i'll give a comma

we'll go to the next line

and this time

we are going to have another animal

i'll say

elephant

give a comma

let's see the age is

63

i'll give a comma

and then we'll have our final

element in the list

let's say the name of the

animal is leopard

give a comma

then we'll have the age of the leopard

let's say

the age is 18

so we have our list ready

now

using a for loop

will filter

the elements in the list giving a

specific condition let me show you

so i'll write for animals in

i'm going to use the filter function

and inside the filter function

i'll

give

an anonymous function called lambda

i'll say lambda i

colon

i of

age

if it is divisible by 2

so i'll say age

divided by 2 equal to equal to 0

give a comma

then we will

print

that animal

give a colon

i'll say print

animals

so what i'm doing here is

i'm using the filter function

and passing my condition that is

if

the age of the animal is divisible by 2

then print the animal

or just print the list

rest

we don't need

all right

now let me run it

it says there's an invalid syntax let me

debug it

okay there is a spelling mistake here in

lambda this should be

mbta

okay now we'll run it there you go

so here in the list that we had created

only the age of lion and leopard were

divisible by two so 30 and 18 were

divisible by two

so python printed us only those two

elements in the list the rest it ignored

11 and 63 are not divisible by two so we

did not get dog and elephant

cool

so this is

another interesting looping technique

where you can use

filter as well as an anonymous lambda

function

all right

now in the next example we'll see how to

remove items in a list using a

while loop so so far we have been using

only for loops

now we are going to see a few examples

using while loop

okay

i am going to create a variable called

country so this variable will hold a

list of elements of the different

country names i'll say india

let's say my

second country is

canada

and let's see my third country i have is

brazil

my fourth country i have is japan

and then we have let's say israel

okay

now

i'll use a while loop so i'll say while

my list that is country

then

to remove the elements in the list i'm

going to use the pop function

so i'll say

print

country

dot i'll say pop and i'll pass

-1 as the parameter so that

it removes the

elements from the

end of the list if i

run it you can see here we have israel

japan brazil canada and india

now you can just

print country

you can see here since we have removed

all the elements from

my list country there is no element left

here so it gives us an empty list

cool

now let me show you how you can use

while loops in just one line

so for that i'll create a variable

called num

and i'll assign a value of 10

i'll say while

num is

greater than 0

i'll say

num

equal to

num minus 1

i'll give a

semicolon this time and then i'll say

print

num

let's run it you can see it here

we have printed

nine

eight seven six up to zero

so in the first iteration my num value

was 10

so 10 greater than 0 was true so we

decreased the value of num by 1 so num

became

9 and we printed 9. in the second

iteration

num which was 9

was greater than 0 then we

decreased or reduced numb by 1 again so

it became 8 then we printed it

and the loop continued till we reached

0.

cool now had this condition been

num

equal to num plus 1 or num plus equal to

1 the loop would have run for infinite

number of times

all right

now i'll

show you an example how to run an

infinite loop

so i'll say while

true

i'll create a variable called num

now this num would be

a user input a user integer input

actually

i'll pass in the message as enter an

integer

give a colon followed by a space

and then we'll say

print

the

product

of

i'll give a comma say num

i'll give another comma

i'll say

is

now we'll pass in our multiplication i

want to

multiply any

user given number by 5

so i'll say 5 multiplied by

num

ok

let's run it and see here enter an

integer if i say let's say 3 so 3

multiplied by 5 is 15 the product of 3

here i can change the message as

multiplied

by five

you can say is

okay

now let's run it

okay

so let's say i enter my integer as 3 i

have the message the product of 3

multiplied by 5 is 15.

let's enter another value 10

the product is 50.

let's say i have 20 the product is 100

let's see i am taking

35 multiplied by 5 is 175 so this loop

will

continue until and unless you don't

interrupt it

so i'm going to interrupt my

kernel

to stop

executing this loop

okay now we are going to explore the

enumerate function in python

but before that let me tell you what

enumerate function is

so the enumerate method or the function

in python allows us to

number list indices of the items as they

are coming out of the array python will

automatically put this indices into a

tuple

let me show you how it works

so i'll directly start with my for loop

i'll say for i in

i'll use the enumerate keyword

and within

brackets i'll pass in my

elements in the form of list

i'll say the

let's say then we have

brown

the next word i have is for

let's see then we have jumped this is

basically a sentence broken down into

different words and those words we have

put

as elements in the list

the next word i have is the

give a comma i'll say

lazy

then we have

dog

give a comma

and finally we'll have our full stop or

the period

okay then i'll give a colon

and i'll say

print

i

now let me run it you can see here using

the enumerate function we have

given

the

indices to the different items in my

list so it starts from zero and goes

till eight so there are total nine

elements in my list

okay

now you can see here the

result has been printed in the form of a

tuple or tuple

i'll just copy the above code and paste

it here

now i'm going to replace i with key

and

value

and

print also i'll say key comma value

let me show you the result you can see

here this time

it is no more at tuple

and here we have the indices and then we

have the

items so basically these indices have

now become the keys and

the items are the values

okay

now you can

print

the different elements in the form of a

sentence let me show you how to do it

i'll just paste it here

and

instead of key i'll say value

and i'll use

the end parameter in the print statement

i'll say end equal to

give us peace

let's run it you can see here

okay this should be brown fox and not

for let's run it again

so we have the sentence the brown fox

jumped over the lazy dog

okay

so similarly you can iterate through the

letters in a word or a string and print

the letters along with the indices

i'll declare a variable called company

and

this will have a value let's say simply

learn

i'll say for i comma

j

in

i'll use the

enumerate function

within brackets i'll say

company

give a colon

then

i'll say print

i comma j

let's see the result there you go so

here we have

indices assigned to the different

letters

in my word simply learn

okay

now moving ahead

so by default the index position starts

at 0 as i told you

now you can also mention the starting

index position using the start parameter

so what i'll do is

i'll copy my

above code

and paste it here now we are going to

make some changes i'll say for

i in

enumerate company

and then i'm going to give my start

parameter let's say i want to start the

index position at 10.

now if i print it

okay let's say print i

there you go here you can see

my first letter starts at index 10 then

we have 11

m at 12 p at 13 and finally we have

the last letter which is n in simply

learn is at the 20th index

cool okay

so now let's explore the zip function in

python and how you can use it to loop it

through two arrays at once

so the zip function returns a zip object

which is an iterator of tuples where the

first item in each

past iterator is paired together and

then the second item in each parse

titrator is paired together and so on

and so forth

so if the past iterators have different

lengths the iterator with the

least items decides the length of the

new iterator

let me

show you

the first example that will help you

understand how the zip function works so

i have a

list called first

and i have a

names of few

football players we have

lionel

then we have cristiano

give a comma and let's say we have

mohammed

i'll declare

another list called last

which will have

values like messi

then we have

ronaldo

basically the

surnames

of leonel christiano and mohammed then

we have salah

i'll write my for loop i'll say for i in

my zip function or the method

i'll pass in first comma last which are

my list names i'll say print

i

let me run it you can see here

using the

zip function we have

iterated through

both the list so we have lionel messi

cristiano ronaldo and then mohammad

salla

all right

now you can combine the elements of

three lists as well

so i'll just paste the code here and

we'll create another list called num

and this is going to be a list of

numbers

let's say

7

and 8 okay

now here i'll say for i

in

zip first last and num print i

if i run it

you see the result here it has zipped

only the

first three items in the

list first last and num so we have

three items printed

okay

now coming to the final section of this

demo on looping techniques in python

we'll explore about

zip underscore longest

so python's iterator tool or iter tool

is a module that provides various

functions that work on iterators to

produce complex citrators

so itreaters in python is an object that

can iterate through sequence data type

such as list tuple string and so on

so the zip underscore longest iterator

falls under terminating iterators it

prints the values of the i tables

alternatively in sequence if one of the

iterables is printed fully the remaining

values are filled with the values

assigned in the fill value parameter

so to use this

function called zip underscore longest

we need to

import zip longest from the item tools

module so i'll say from

iter tools

import

zip underscore longest

okay

then i'll

create my

first list

i'll

say let me go to the top and copy the

elements because we are going to use

these same elements again

i'll paste it here

okay

and let's say i'll give a comma and we

are going to

and i'm again going to use the

three elements okay

now i'll create another list called last

and we are going to copy the items

from the top

paste it here

and now

i'll say

for let me just scroll down

i

in

zip underscore

longest

within brackets i'll say first comma

last

we're going to print i

let me

run it and show you the result

this should be zip underscore longest

okay you can see the result

here for the first

three items it has printed lionel messi

cristiano ronaldo and mohamed salah

which you can see here but for the

last three items in the

first list it has given us

none because there were no values

now to overcome this problem you can use

a parameter called fill value

let me just copy this

and i'll paste it here

and the only change that i'm going to do

here is

i'm going to say

i'll give a comma

i'll use the parameter called fill value

equal to i'll say n a

if i run it you can see here

for the last three now we have whatever

we have

defined within field value parameter you

can change this to let's say

not defined

there you go

all right

so

these were some of the interesting

examples that we implemented using

looping techniques in python this is

going to be a completely hands-on demo

video and we'll be using the jupyter

notebook to work on the examples

so let's head over to our jupyter

notebook and begin

okay so i'm on my jupyter notebook first

of all let's rename our notebook to

looping techniques

okay

i'll just increase the

size

all right

okay

so let's see how you can arrange the

values in a list using for loops with

python sorted function

so i'll create a variable called num

and

i'll assign a list let's say it has

values 2 5

10

4

i'm taking just random values

let's say 36

50

and 49

so this is my list now i want to arrange

the

items in this list

in either ascending or descending order

so for that i can use a for loop i'll

say for i which is my iterator variable

in

and after this i'm going to use the

python sorted function

and inside the function i'll pass in my

variable which is num

then i'll give a colon and say print i

so let's

hit shift enter to run it

okay

you can see here

so python by default

has sorted the elements in the list in

ascending order so we have 2 4 5 10 10

36 49 50 and

50.

now let's learn how you can sort the

values in a list using a for loop in

descending order

so

i'll just

copy my above cell of code

we'll paste it here it will help

save us some time

so i'll say for i

in sorted

i have given my variable num

after this

i am going to pass in another parameter

called reverse

equal to

i'll say true

now reverse equal to true will make sure

python will sort the list in descending

order

if i run it

you can see the difference we have

sorted the elements in the list num in

descending order now so we have 50 50 49

36 10 5 4 and 2.

okay so this is one of the

techniques that you can use

to sort the elements in a list using a

for loop

now similarly you can also sort string

elements alphabetically in a list in

ascending or descending order

so for that i'll create a variable

called players let me just scroll down

then i'll create a list

which will have the

names of

football players let's say we have messi

then let's say we have

ronaldo

then we have salah

and then we have let's say harry

okay

i'm going to say for i

in

my function sorted

i'll say

players

i'll give a comma

and again use reverse equal to true

so

this is going to sort

the

items in my list players in descending

order of

the alphabets

then

i will give a colon and say

print i

let me run it you can see here

the names of the different football

players have been sorted in descending

order of

alphabet so we have s appearing first

then r m and h so salah ronaldo messi

and harry

alright now let's move ahead

now we are going to create a dictionary

of

key value pairs and sort it

so i'll create a dictionary called d

which will have

a few key value pairs so my first key is

f and the value is let's say 1

then my second key let's say is b

and the value is 4

give a

comma my next key is a

and the value is let's say 3

after that my next key is e

and the value is let's say 9

and finally we have our last key which

is c and the value is 2.

now to sort this dictionary i'll say for

i

in

sorted

i'm going to use the

items method

i'll say sorted d dot items

and then will print i

let me run it and show you the result

you can see it here

our dictionary has been sorted in

ascending order of the dictionary keys

so we have a b

then c there is no d here

after that we have e and then f

cool

now you can also sort the

keys and values separately let me just

copy this and i'll show you

i'll paste it here

and instead of d dot items i'll just say

d dot keys

if i run it you can see here we have

sorted only the

keys in my dictionary

now to sort the values instead of items

you can just write values

and here you can see we have

sorted the values in the dictionary d in

ascending order again so we have one two

three four and nine

all right

now we will understand how to use the

reverse function in loops to reverse the

items in a list

so i'll again

create my

list called players which will have

messy let's see again the next player is

ronaldo

and

then we have

salah and then we have harry

okay

now to

reverse the elements in this list called

players i'll say for

i in

then i'll use the reversed function and

pass in my list called players

give a colon and then say print i

let's run it here you can see

we have reversed the

elements in my list called players so we

have harry first then salah ronaldo and

messi in the end

cool

now moving ahead

we'll see how to use the filter function

in loop and filter specific elements in

a list based on some conditions now to

give the condition we'll be using an

anonymous function in python that is

often called as the lambda function

to do this

i'm going to create a list

called animals

i'll give my square brackets

and inside these square brackets

i'm going to

pass in the elements in the form of a

dictionary so to pass in a dictionary we

need to have key value peers

so my first key is name

let's see

my animal is

dogs

i'll give a comma

then my next key is the age let's say

dog's age is 11.

so this is my first

list element which has been passed in

the form of a dictionary

i'll create another curly bracket and

we'll have the same keys

this time let's say

my animal is lion

let's make it dog instead of dogs

okay

give a comma and then say

age

let's see the age of the line is 30

i'll give a comma

we'll go to the next line

and this time

we're going to have another animal

i'll say

elephant

give a comma

let's say the age is

63

i'll give a comma and then we'll have

our final

element in the list

let's say the name of the

animal is leopard

give a comma

then we'll have the age of the leopard

let's say

the age is 18

so we have our list ready

now

using a for loop

will filter

the elements in the list giving a

specific condition let me show you

so i'll write for animals in

i'm going to use the filter function

and inside the filter function

i'll give

an anonymous function called lambda

i'll say lambda i

colon

i of

age

if it is divisible by 2

so i'll say age

divided by 2 equal to equal to 0

give a comma

then we will

print

that animal

give a colon

i'll say print

animals

so what i am doing here is

i am using the filter function

and passing my condition that is

if

the age of the animal is divisible by 2

then print the animal

or just print the list

rest

we don't need

all right now let me run it

it says there's an

invalid syntax let me

debug it

okay there is a spelling mistake here in

lambda this should be

mbta

okay now we'll run it there you go

so here

in the list that we had created

only the age of lion and leopard were

divisible by two so 30 and 18 were

divisible by two

so python printed us only those two

elements in the list the rest it ignored

11 and 63 are not divisible by 2 so we

did not get dog and elephant

cool

so this is another interesting looping

technique where you can use

filter as well as an anonymous lambda

function

all right

now in the next example we'll see how to

remove items in a list using a while

loop so so far we have been using only

for loops

now we are going to see a few examples

using while loop

okay

i'm going to create a variable called

country so this variable will hold a

list of elements of the different

country names i'll say india

let's say my

second country is

canada

and let's say my third country i have is

brazil

my

fourth country i have is japan

and then we have let's say

israel

okay

now

i'll use a while loop so i'll say while

my list that is country

then

to remove the elements in the list i'm

going to use the pop function

so i'll say

print

country

dot i'll say pop and i'll pass

-1 as the parameter so that

it removes the elements

from the

end of the list if i

run it you can see here we have israel

japan brazil canada and india

now you can just

print country

you can see here

since we have removed all the elements

from

my list country there is no element left

here so it gives us an empty list

cool

now let me show you how you can use

while loops in just one line

so for that i'll create a variable

called num

and i'll assign a value of 10

i'll say while

num is

greater than

0

i'll say

num

equal to

num minus 1

i'll give a

semicolon this time and then i'll say

print num

let's run it you can see it here

we have printed

nine

eight seven six up to zero

so in the first iteration

my num value was 10

so 10 greater than 0 was true so we

decreased the value of num by 1 so num

became

9 and we printed nine in the second

iteration

num which was nine

was greater than zero then we

decreased or reduced num by one again so

it became eight then we printed it

and the loop continued till we reached 0

cool

now had this condition been

num

equal to num plus 1 or num plus equal to

1 the loop would have run for infinite

number of times

all right

now i'll

show you an example how to run an

infinite loop

so i'll say while

true

i'll create a variable called num

now this num would be

a user input a user integer input

actually

i'll pass in the message as enter an

integer

give a colon followed by a space

and then we'll say

print

the

product

off

i'll give a comma say num

i'll give another comma

i'll say

is

now we'll pass in our

multiplication i want to

multiply any user given number by 5

so i'll say 5 multiplied by num

okay

let's run it

and see here enter an integer if i say

let's say 3

so 3

multiplied by 5 is 15 the product of 3

here i can change the message as

multiplied

by 5

let's say is

okay

now let's run it

okay

so let's say i enter my integer as 3 i

have the message the product of 3

multiplied by 5 is 15

let's enter another value 10 the product

is 50

let's say i have 20 the product is 100

let's see i am taking

35 multiplied by 5 is 175 so this loop

will

continue until and unless you don't

interrupt it

so i'm going to interrupt my

kernel

to stop

executing this loop

okay now we are going to explore the

enumerate function in python but before

that let me tell you what enumerate

function is

so the enumerate method or the function

in python allows us to number list

indices of the items as they are coming

out of the array python will

automatically put this indices into a

tuple

let me show you how it works

so i'll directly start with my for loop

i'll say for i in

i'll use the enumerate keyword

and within

brackets i'll pass in my

elements in the form of list

i'll say the

let's say then we have

brown

the next word i have is for

let's say then we have jumped this is

basically a sentence broken down into

different words and those words we have

put

as elements in the list

the next word i have is the

give a comma i'll say

lazy

then we have

dog

give a comma

and finally we will have our full stop

or the period

okay then i'll give a colon

and i'll say

print

i

now let me run it

you can see here using the enumerate

function we have

given

the indices to the different items in my

list so it starts from 0 and goes till

8. so there are total 9 elements in my

list

okay

now you can see here the

result has been printed in the form of a

tuple or tuple

i'll just copy the above code and paste

it here

now i'm going to replace i with

key

and

value

and

print also i'll say key comma value

let me show you the result you can see

here this time

it is no more at tuple

and here we have the indices and then we

have the

items so basically these indices have

now become the keys and

the items are the values

okay

now you can

print the different elements in the form

of a sentence let me show you how to do

it

i'll just paste it here

and

instead of key i'll say value

and i'll use

the end parameter in the print statement

i'll say end equal to

give a space

let's run it you can see here

okay this should be brown fox and not

far let's run it again

so we have the sentence the brown fox

jumped over the lazy dog

okay

so similarly you can iterate through the

letters in a word or a string and print

the letters along with the indices

i'll declare a variable called company

and

this will have a value let's say simply

learn

i'll say for i comma

j

in

i'll use the

enumerate function

within brackets i'll say

company

give a colon

then

i'll say print

i comma j

let's see the result there you go so

here we have

indices assigned to the different

letters

in my word simply learn okay

now moving ahead

so by default the index position starts

at 0 as i told you

now you can also mention the starting

index position using the start parameter

so what i'll do is

i'll copy my

above code

and paste it here now we are going to

make some changes i'll say for

i in

enumerate company

and then i'm going to give my start

parameter let's say i want to start the

index position at 10.

now if i print it okay let's say print i

there you go here you can see

my first letter starts at index 10 then

we have 11

m at 12 p at 13 and finally we have the

last letter which is n in simply learn

is that the 20th index

cool okay

so now let's explore the zip function in

python and how you can use it to loop it

through two arrays at once

so the zip function returns a zip object

which is an iterator of tuples where the

first item in each

past iterator is paired together and

then the second item in each pass

titrator is paired together and so on

and so forth so if the past iterators

have different lengths the iterated with

the least items decides the length of

the new iterator

let me

show you

the first example that will help you

understand how the zip function works so

i have a

list called first

and i have a

names of few

football players we have

leonel

then we have cristiano

give a comma and let's say we have

mahmud

i'll declare

another list called last which will have

values like messi

then we have

ronaldo basically the

surnames

of leonel christiano and muhammad then

we have salah

i'll write my for loop i'll say for

i

in

my zip function or the method i'll pass

in first comma last which are my

list names i'll say print

i

let me run it you can see here using the

zip function we have

iterated through

both the list so we have lionel messi

cristiano ronaldo and then mohamed salah

all right

now you can combine the elements of

three lists as well so i'll just paste

the code here and we'll create another

list called num

and this is going to be a list of

numbers

let's say 7

and 8 okay

now here i'll say for i

in

zip first last and num print i

if i run it

you see the result here it has zipped

only the

first three items in the

list first last and num so we have

three items printed

okay

now coming to the final section of this

demo on looping techniques in python

we'll explore about

zip underscore longest

so python's iterator tool or iter tool

is a module that provides various

functions that work on iterators to

produce complex iterators so iterators

in python is an object that can iterate

through sequence data types such as list

tuple string and so on

so the zip underscore longest iterator

falls under terminating iterators it

prints the values of the i tables

alternatively in sequence if one of the

iterables is printed fully the remaining

values are filled with the values

assigned in the fill value parameter

so to use this

function called zip underscore longest

we need to

[Music]

import ziplongist from the item tools

module so i'll say from

either tools

import

zip underscore

longest

okay

then i'll

create my

first list

i'll say

let me go to the top and copy the

elements because we are going to use

these same elements again

i'll paste it here

okay

and let's see i'll give a comma and

we're going to

and i'm again going to use the

three elements okay

i'll create another list called last

and we're going to copy the items

from the top

paste it here

and now

i'll say

for let me just scroll down

i

in

zip underscore

longest

within brackets i'll say first comma

last

we're going to print

i

let me

run it and show you the result

this should be zip underscore longest

okay you can see the result here

for the first

three items it has printed lionel messi

cristiano ronaldo and mohamed salah

which you can see here but for the

last three items in the first list it

has given us

none because there were no values

now to overcome this problem you can use

a parameter called fill value

let me just copy this

and i'll paste it here

and the only change that i'm going to do

here is

i'm going to say

i'll give a comma

i'll use the parameter called fill value

equal to i'll say na

if i run it you can see here

for the last three now we have whatever

we have

defined within field value parameter you

can change this to let's say

not defined

there you go

all right

so

these were some of the interesting

examples that we implemented using

looping techniques in python we're going

to learn what is the control statement

and then understand the different types

of control statements in python so we

have continuous statement break

statement and past statement we are

going to

understand these in detail with hands-on

demonstrations in python on the jupiter

notebook

so what is the control statement

python programming language provides

loop control statements that can be used

to change the flow of execution and

execute a statement or group of

statements multiple times

in certain circumstances when some

particular conditions occur

we may want to exit from a loop or skip

some statements of the loop before

continuing further in the loop

so to achieve this we need the help of

control statements in python

now python provides three types of

control statements first is continue

then we have break and then we have pass

so let's look at them one by one in

detail

so the continue statement skips the

execution of the remaining statements in

the loop and proceeds with the next

titration in the loop that is it forces

the loop for the next iteration ignoring

the subsequent instructions

now on the right you can see the

flowchart of continue statement in

python so on the top we have the

test expression

now if the test expression evaluates to

false we just exit out of the loop

but if the test expression is true then

we head to our continue statement now if

this is

yes or true we again check the test

expression

if it is false or no then we execute the

statements after the continue statement

now we'll understand how the continue

statement works with the help of

examples in our demo session

so let's

see the next

statement that we have which is the

break statement

now in python the break statement is

used to terminate the loop whenever the

python interpreter or the compiler comes

across the break statement it jumps out

of the loop so it skips the remaining

code without further testing the test

expression of that loop

now here on the right you can see the

flowchart how the

break statement works in python

on the top we have the test expression

now if the

test expression evaluates to false we

exit the loop but

if it is true then we

execute the break statement

if it is yes then we

just exit the loop but if it is no then

we execute the remaining statements

after the break statement now moving to

the final control statement that we have

in python

which is the pass statement so the pass

statement in python is used as a

placeholder for future implementation of

functions loops etc

when the pass statement is executed

nothing happens actually but you avoid

getting an error when an empty code is

not allowed

it is also known as a null statement

now

let's directly jump to a jupyter

notebook where we'll explore

break continue and pass statements in

python in detail

okay so here i am on my jupyter notebook

let me first go ahead and

rename my notebook to

control statements in python

i'll click on rename

ok

now let's see how the

continue statement works in python

for that

i'm going to print

all the letters

except the letter i in the string simply

learn

so i'll give a comment as

continue

statement

okay

so i'll first write my for loop i'll say

for

letters

in my string that is

simply learn

give a colon

and then

i'll say if

letters is equal to equal to

let's say i

then i'm going to use the

continue statement

after that i'm going to say

print

letter

give a colon give a comma and then

we are going to print the individual

letters in the string

that is simply learn

so here

letters is actually the iterator

variable

it could be any valid

python variable

finally i am going to say print

end of execution

so here what i am doing is i want to

print all the letters except the letter

i in my string simply learn so whenever

the

i occurs in my string simply learn we'll

use the continue keyword and then move

on to the next

letter in the string simply learn if i

hit shift enter you can see the result

there you go

here you can see we have s

and the next word was i so we

skipped

that iteration and then we continued

with the next iteration so we have m

p

l and again here we

had another i present in the string so

we skipped this iteration as well and

moved on with the next so l e a r and n

finally we have printed end of execution

so this is how the continue statement

works

you can use it in a for loop or you can

use it in a while loop as well

now let's see another example where we

are going to display only odd numbers

present in a list of numbers

so

i'll say for

num which is my iterator variable i'll

say for num in

my list which

has a few numbers let's say

10

7 i have 17

let's say 42

33 19 and let's say 60.

okay

so for num in my list which is this one

i'll say if

num

mod 2 is equal to equal to 0 so if the

remainder is 0 i'll say continue

and then

we are going to

print num

so what we are doing here is for each

number

or each

item in my list which has

a list of numbers i am going to check if

that number is divisible by 2 or not if

it is divisible by 2 we are going to

skip the titration and we are going to

move ahead with the next number

so let's run it okay here you can see we

have printed or displayed all the odd

numbers that were present in my

list which is this one

so this was another simple example

of using a continue statement in python

now let's move on to the

next control statement which is break

again we are going to look at a few

examples here

all right

now the first example

we are going to see is how to break the

execution when the

number five comes up in the tuple

so for that we are going to use a while

loop now

first of all let me declare a tuple

which has let's say one two three four

five six seven and eight so numbers from

one till eight

i'm going to say

count equal to zero

and then i'm going to use a while loop

i'll say while

my count is less than 9

then i'm going to write my print

statement print

my tuple which is num

and using square brackets i'll say count

now

we're going to increment count by 1 so

i'll say

count equal to

count

plus one

next we will check if

the value of count is equal to equal to

five

i'll give a colon and then we are going

to break out of the loop

finally

we'll print

end of execution

okay

so

this code

will help break the execution when the

number five comes up in the

tuple which is num

so let's run it

okay so here you can see

as soon as the number five

occurred in the tuple

we broke out of the loop and

the break statement terminated the

execution of the loop so

you can see here we did not print 6 7

and 8 and finally we printed our last

statement which was present after the

break statement that is end of execution

okay

so i hope

this helped you understand how the break

statement works in

python

we're also going to see another example

now

so this is using a for loop

so we are going to break and terminate

the execution when the letter p occurs

in the string

simply alone

so earlier we had seen one example which

was our first

example where we saw how to use continue

statement for the same string simply

loan

this time

we are going to use the break statement

to

terminate the execution when the letter

p occurs in the string simply alone

so i'll start with a for loop i'll say

for

letters in

my string which is

simply learn

i'll give a colon

and then i'll say

print

my message that is

letter

give another colon i'll give a comma and

i'll put my

i treat a variable which is letters

then i'll say if

letters

equal to equal to

p will give a colon and then

i want to break out of the loop

now let me just

print it

you can see here

as soon as

the letter p occurred in the iteration

we

came out of the loop so

the break statement executed the above

lines of code and

the moment is

saw the letter p it just terminated the

loop and hence you can see we did not

print the remaining

letters in the string simply learn

okay

now moving to our

final section of the demo where we will

see how to use

pass statements in python

so the first example we are going to see

under past statement is

to check if the number is odd

so if the number is odd we are going to

pass it

else

we are going to print only the even

numbers

okay

so for that i'm going to use

a for loop but before that let me just

give a

comment i'll say pass statement

okay

so in the first example we'll check if

the number is odd then we are going to

pass it and only print the even numbers

so for that i'm going to use a for loop

i'll say for number in

range let's say i'm taking the range

between 10 and 25

give a colon i'll say if

number

mod

2

if it is not equal to

0

give a colon then we are going to

pass it

so this means if the number is odd then

just pass it

else

i'll say print

the

number

is

give a colon

a comma and then i'll pass in my

iterator variable which is number

now let's run it

okay you can see here

in the range

10 and 25 we have

excluded all the

odd numbers because we used the pass

statement so it passed printing all the

odd numbers and it just printed whatever

was there in the else part that is the

even numbers so we have 10 12 14 then we

have 20 22 and 24

so these are all the even numbers that

lie between

10 and 25

all right

now coming to the final demo

so here i'm going to write a user

defined function

to print any number other than

10.

so again we are going to use a pass

statement for this

so let me write my user defined function

i'll use the def keyword

and my function name let's say print

underscore num

then i'll pass in my parameter let's say

number

i'll say if

number is

10

then i'll use the

pass statement

otherwise i'll say else

print

the number

is

i'll give a comma and then i'll say

number which is there in my parameter

now let's run it

now we are going to call the function

using the

function name which is print num

if i say

print num 20

it will print my number saying the

number is 20.

let's copy this

i'll paste it here

let's say i'll say

25000

it's going to print 25000

but

if i say print num 10

you can see it here that

python has just passed it because we had

given in our condition if number is 10

then just pass it

so there was no output for 10

all right

so that brings us to the end of this

demo session on

control statements in python so we

looked at how the continue statement

works then we saw how the

break statement works we looked at two

examples one was with while loops and

the other one was with for loop and

finally we saw

two examples on past statements one was

using

for and if else and the other one was

using a user defined function and inside

that we use the file's condition

conditional statements in python perform

specific operations and take actions

depending on whether a specific boolean

constraint evaluates to true or false

conditional statements are handled by

blocks of if statements in python

now conditional statements are also

known as decision making statements

so python provides different types of

conditional statements that you can use

to make decisions

we have the simple if statement

then we have if else statement

elif statement the nested if statement

as well as nested if statement we will

learn them one by one with the help of

the syntax and code examples

so this is how the syntax of if

statement looks like so you pass in the

if condition and then we have

a set of statements inside the if

condition

so on the right side you can see the

flow diagram how the if statement gets

evaluated so first we have the test

expression

that is the if condition now if this

expression evaluates to true then we go

inside the body of the if statement so

this is basically

the body of the

if statement that contains a list of

statements or blocks of statements

now if the test expression evaluates to

false

we execute

the statements that are present after

the if condition

all right

now let me take you to my jupyter

notebook where we will

understand if statement with an example

okay so here i am on my

jupyter notebook i'll just rename this

to

conditional statements

i'll see it as demo

and we'll rename it okay

i'll just expand the

screen size

all right okay

so first of all let's

write a simple if statement

i have given a comment here

suppose we have a variable called

grade

and the value of grade is 80

then i'll write my

if statement as if

grade

is greater than equal to

50

then i'll give a

colon

then i'll write a print statement print

passed in the

exam

now this is how you write a simple if

statement so you have the if keyword

followed by

the condition so here my condition is

i'm checking whether the grade is

greater than equal to 50. now here

i've already defined my grade to 80

so this if statement or the if condition

will check whether 80 is greater than

equal to 50. now this is true

then

my print statement gets executed

let me run it and show you the result

there you go here you can see we have

our

printed message as passed in the exam

because 80 is greater than equal to 50.

now what if i change this to let's say

30

if i run this there is no output here

the reason being

30 is

greater than equal to 50 is false so

my print statement did not execute

ok

now if you want

you can

also print

another statement outside the if

condition

i'll give the message as

execute

statement

after if

now one thing to remember that

this print statement is outside the if

condition

so if i run it

only my

last print statement gets executed which

is outside the

if condition

okay

now let's write another

simple

if statement

now this time

we are not going to define the grade

value or

predefine the grade value here we are

going to take the grade value as an

input that is a user input so i'll write

grade equal to

now the way to take a user input is by

using the input function

so first of all we need to convert

our entry into an integer so i'll write

int function and inside that i'll pass

in my input function

then

i'll give my message as enter the number

all right so this statement will take

the

number from the user

now i'll write my if statement if

grade is greater than equal to

50

then

it won't give a space here

let's delete this piece

then i'll write print

you have

passed in the exam

okay

let's run it you see here

my program is asking for the

user input it says enter the number i'll

give my number as let's say 60.

if i hit enter

that gives me the result passed in the

exam

now let's run it again

this time i'm going to give as let's say

35

if i run it

there is

no output here the reason being our

grade 35 is not greater than equal to 50

so our print statement did not execute

all right okay now let me give a space

here we'll run it again and this time

we'll pass our grid as let's say

75

let me run it you can see here

it gives me the message passed in the

exam

now moving to our next statement we have

the if else statement so this is how the

syntax of if else statement looks like

so first you have the if condition

followed by a colon

if this condition evaluates to true then

we execute the list of statements that

are present inside this if condition

else

we have the else block here

if this condition returns

false then we execute the

list of else statements

so here is the

flow of how the

if statement executes the different

statements

so first we check the test expression

if that evaluates to true

then we have the body of if

and if it is false then we have the

body of else

and later

there are any statements that are

present outside the effects block will

execute those statements

now let's head over to our jupyter

notebook and we'll see

how the file statement works by example

okay

so here

i'll show you another example of using

two if statements

so i'll define my grade as 40

i'll write if

grade

is greater than equal to 50

then will

print

let's say

pass

then

i'll write another if statement

i'll say grade is

less than

50

then we'll print

fail

now here i'm using two if statements let

me run it

you see here

i have my result as fail the reason

being our grade 40 is less than 50 and

hence it has printed fail

now instead of using two if statements

you can use the if else statement

so in this case we'll have our if

statement checked for if grade is

greater than equal to 50

if this is true then we'll print

whatever is there inside the if

statement but in case this evaluates to

false we have another

else block that we are going to write

let me show you how to write the full

statement

so i will give a comment as

if else

okay

i'll say

grade equal to 40

then

we'll check if grade

is greater than equal to 50

print

pass

then

instead of using

the if statement again i'll write else

followed by a colon and then i'll write

print

fill

make sure this field is inside

double quotations

if i run it

it gives me the result fail the reason

being

40 is not less than

repeat 40 is not greater than equal to

50 so hence it has printed field

now instead of taking

the value as 40

we can have the

user give the input so we'll use the

input function

i'll say

enter

the

grade

let's run it again you see here my

program is asking for the user input

let's say i'll give 80

will

run it

it says pass because 80 is greater than

equal to 50 let me run it again this

time let's see i'll pass

my grid as 45

will run it

it gives us fail

all right

now moving to our next

conditional statement we have the

ellipse statement

now this is how the syntax of ellipse

statement looks like

so here first we have the if condition

now if the if condition evaluates to

true we have the body of if there is

basically a set of statements

now if the first test expression or the

if condition evaluates to false then our

alif condition gets executed now if our

l if condition is true then we have the

body of alif so this is the ellipse

statement body

finally

if the alif condition also evaluates to

false then we have the block of else

statements you can see here

we have

body of else and later if there are any

statements outside this

if alif and else block then those

statements get executed

now we'll see this with the help of

examples

okay

so here on my

cell i'll give my

comment as

if statement

okay

suppose

i have a variable called score

and

this take the value

as integer from the user so i am using

the input function

i'll say

enter

the

score

i'll give a space

then

i'll write my

if condition i'll say if score

is

let's say greater than equal to 90

give a colon

then we'll print

our message as

passed the

exam with let's say a grade

i'll just copy this statement because we

are going to

print

similar statement

below as well

and now i will have my

alif condition i'll write

lf

alif is actually else if

score is greater than

equal to

let's say

75

i'll give a colon

will print

past the

exam with

b

grade then i'll again have my

alif

statement i'll write if score

is greater than equal to let's say

60

will print pass the exam with

c grade

next

let's write another alif condition i'll

write lf

if score

is

greater than

this should be greater than equal to

okay

is greater than equal to

let's say

40

then we'll print past the exam with

d grade

and finally

we'll have the

else condition

i'll write

print let me just scroll down

failed

in the exam

okay

so this is how you write a

life conditional statement so first i am

taking the user input of the score then

i am checking if score is greater than

equal to 90 i am displaying my message

as pass the exam with a grade then i

have a list of

alif statements

to check for different scores

if all these evaluates to false i am

having my else statement printed

let's

run it

okay

so we'll try out different

scores

let's say

someone scored 95

if i run it

so that

candidate has passed the exam with

e-grade because

if you see the condition my score 95 is

greater than equal to 90 and hence we

have passed the exam with a grade as the

message

run it again let's say i have 80.

if i run it it says pass the exam with b

grade the reason being 80 is greater

than equal to 75 and hence we have this

message printed

let's run it again suppose someone

scored let's say 25.

if i run it

okay

it throws me an error it says name

score not defined

okay so this should be score actually

here there was a spelling mistake

i'll run it

i'll pass my score as 25

it gives me failed in the exam the

reason being my score

25 is less than equal to 40 and hence we

have failed in the exam

cool

now you can also use a for loop and then

have a list of a full block or if else

statements

let me show you how to do it

suppose i write for x in i'll use the

range function

i'll go till

10 which means from 0 to 9

then i'm checking if

my x

is

less than equal to 3

i'll print

x

is

less than or

equal to

3

okay

now

we have the

ellipse statement if l if

x greater than

5 i'll print

x

is

greater than

five

then we have the

else condition

will print let me just scroll down

i'll print x

must be

four

or

five

okay

so

here i have used a for loop and i am

[Music]

checking for each iteration from 0 to 9

and then we have a set of if elephant

else statements let's run it

there you go you can see the output here

so first

in my range i have 0

so it will check if 0 is less than equal

to 3 which is true so it has printed 0

is less than or equal to 3

so it will go till 3

and then

when 4 comes it will check if

4 is greater than 5 now this is also

false so it will skip executing the lf

statement and it will print whatever is

there in the else

block which is

four must be four or five so you can see

the message here four must be four and

five similarly for five also the same

message will be printed the reason being

5 is not greater than 5

and then for the rest of the

numbers from 6 to 9 we have

6 is greater than 5 7 is greater than 5

8 is greater than 5 and 9 is greater

than 5

all right

now moving ahead

next we have the

nested if statement so here is the

syntax of nested if so you have the if

condition and inside the if condition

you have another if condition and hence

it becomes the

nested if condition statement

and inside this condition you have the

list of statements or the blocks of

statements

so here is how the flowchart or the flow

diagram looks like

so first

we are evaluating the expression1 which

is this condition

if it is true we are going inside and

checking the second condition

if that is also true then we are running

the body of it which is this part of the

syntax

and later if there are any statements

that are present outside the if

condition we are executing those

so in case the first test expression

evaluates to false we are coming outside

and directly printing

whatever is there outside

the if condition

let's

see this with the help of an example

okay so i'll give my

comment here as nested if

cool

so first of all i'll declare a variable

called num

now this

num will have a

user input

value

so i'll write input

enter the

number

then

i'll have my first

if condition

i'll say if

number or num is less than 250

i'll give a

colon

then we'll use the print statement

num

is

smaller than

250.

i'll write my second if statement

and we'll check if num is

less than

180

and will print

num

is smaller

than

180 as well

finally i'll have my

else statement as

print number

is

greater than

180

all right let's run this

and first we'll check with the number

100

okay there you go

so here i'm checking whether 100 is less

than 250 which is true so we have

printed 100 is smaller than 250 again we

are checking if 100 is less than 180

which is true again

so we are printing 100 is smaller than

180 as well there's a spelling mistake

okay

now let's see for let's see 150

again we have 150 smaller than 250 150

also smaller than 180

let's run it this time let's say we'll

pass

300

okay you can see our

result here

300

is

less than 250 is false so we'll skip

printing this again we'll check whether

300 is less than 180

which is false again so we'll skip

printing this statement as well

we'll only have our else block printed

which is 300 is greater than 180

okay

now coming to the final section where

we'll see about nested files

so here you can see we have the syntax

for nested if else statement

so we have an outer if condition and

inside that we have another if condition

then we have

the list of

statements or the body of the if

condition

if this is false then we execute the

else part

and after that we also have an outer

else

statement

so this is how

the flow diagram looks like we'll check

for the test expression one

if that is true then we'll go inside and

see the test expression

too

and if that is true we'll execute the

body of if statement which is this part

of the syntax

then

if these are false then we'll see the

body of else one

if the second expression is false then

we go to the body of else two

and after that if there are any more

statements we'll execute them as well

all right

we'll see an example here

so i'll give my comment as

nested

if else

okay so i'll declare a variable a which

will

take a user input

of type integer

i'll say

enter

the

number

i'll write if e is less than 50

so this is my first if condition

if this is

true this should be less than 50

okay so if my first if statement is true

then we'll

check for the second if statement which

is let's say if

a

modulus 3 equal to equal to 0 which

means if the remainder of the division

is 0

then we say

print

a

is

divisible

by

3

and

is

less than

50.

okay

then we have our

else statement as else

print

my number e

is

not

divisible

by 3

but

is

less than 50.

finally

i'll have my

last

else statement

where i'll print my number e

is greater

than 50

okay so this is how you write a nested

if full statement so i am taking my

number as a user input

first i am checking that number is less

than 50

if that is true i'm again checking if

that number is divisible by 3 if it is

divisible i am printing my message as

the number e is divisible by 3 and is

less than 50.

if this is false i am saying

the number e is not divisible by 3 but

it is less than

50

else i am saying the number is greater

than 50. let's run this

and we'll try out different

examples let's say i'll say my number is

12.

my message is 12 is divisible by 3 and

is less than 50 which is

this part of the code so my number 12 is

less than 50

this is true then i'm again checking

whether 12 is divisible by 3

it evaluates to true and hence we have

this result printed

okay let's say this time i'll say 30

so i have my message 30 is divisible by

3 that is less than 50.

let's run it again and this time let's

say we'll say 72

so here i have my message 72 is greater

than 50. the reason being 72 less than

50 is false

hence this part of the code is not

executed it will directly come to the

else part

which says 72 is greater than 50.

okay

so that brings us to the end of this

demonstration on conditional statements

in python so first we learned how to

write simple if statement you saw how to

take inputs from the user

we also learnt how to write

if else statement

then you learnt about

elif statement

you also saw how to use a for loop and

inside that you can use your if

statement your lf your else

later on we saw how to write nested if

statements and finally we learnt how to

write nested efl statements

cool now let's see the agenda for today

first we will learn about the lists in

python its characteristics and explore

it in jupyter notebook then we will

learn about the pulse in python its

characteristics and we will also explore

tuples in jupyter notebook after that we

will have a look at dictionaries in

python its characteristics and will head

to jupyter notebook to understand the

dictionaries

so lets start with lists in python

imagine

you have different values

you have numbers you have strings now if

you want to group them together

you can do this job in python with the

help of lists or you have work with

arrays in any other language like c plus

or java this is the similar stuff in

here which is list

a list can be defined as a collection of

objects values or items of different

types and these collections are enclosed

within the square brackets and are

separated by commas

let's understand this with the help of

an example

we will create a list and name it as

list1 and insert the elements in square

brackets and separate them with the help

of commas

list 1 equal to square brackets one

comma adam

coma 107 comma usa

and unless we have our first element at

zeroth indexed and we have one at zero

index atom at one index 107 at second

index usa at third index

and talking about the reverse index it

starts with -1 index value we have usa

at -1 index value 107 at minus 2 index

value adam at minus 3 index value and 1

at -4 index value

we will explore the list with various

examples in jupyter notebook in a while

till then let's look at the

characteristics of lists

first the lists are ordered when we say

that lists are ordered it means that the

items have a defined order and that

order will not change if you add new

items to a list the new items will be

placed at the end of the list

second elements of the list can be

accessed by index values

third list can store various types of

elements for example numbers strings or

lists itself

fourth lists are mutable

the list is changeable meaning that we

can change add and remove items in a

list after it has been created

lists allow duplicate elements since

lists are indexed list can have items

with the same value let's have a look at

some methods of lists in python

the first one is append it adds an

element at the end of the list

for syntax we can write list1 dot append

and in round brackets we have to write

the element which we want to append

the next is insert it adds an element at

the specified position its syntax is

name of the list dot insert and in round

brackets we'll write the index at which

we want to insert the element and comma

and after data element which we want to

insert

third is extend

it adds the element of a list to the end

of the current list

its syntax is list1 dot extend and in

round brackets we will add the element

like list2

which we want to extend in the list

the next is index it returns the index

of the first element with the specified

value and its syntax is list1 dot index

and the element which you want to fetch

the index

the next is remove it removes the item

with the specified value

its syntax is

dot remove and in round brackets we

write the element which we want to

remove from the list

the next is sort

this method is used to sort the list

its syntax is list1 dot sort

the next is reverse

it reverses the order of the list

its syntax is list1 dot reverse

let's move to jupyter notebook to

explore these methods

let's start with creating a list

we'll name the list as list1

and we'll create

equal to

and we'll start with square brackets

and we'll write our first element that

would be apple

space

next element

orange

coma space the next element

banana

coma space the next element

key v

now we will get this list printed for

that we'll write the syntax

print and in round brackets we'll write

the list name that would be list1 and

run the command you can see here that

the list is printed

now let's create a different list with

some different elements

list 2

equal to

and in square brackets will write

apple

now we will insert a list

in a list

for that

we will write a list in square brackets

8 comma 4 comma

6

and coma the next element that will

write orange

the next element banana

now print this list

to print this will write print round

brackets will write list2

and run the command here we will get the

list

to print it

we can access any element in the list so

for that we will write the syntax

print

we want to access the second element

that will be the third element from the

list one for that we'll write the syntax

print

list one and in square brackets we'll

write the index two and run the command

we will get the third element from the

list one that is banana

now we will access an element from the

list2

for that we'll write the command print

list2

and in square bracket we will write 1

and in square bracket we'll write 2 and

run the command what we get is 6

so to access an element from a list that

is already inserted in and list we have

to write this syntax

so this syntax tells us that we will

first access the first index element

that is 846 the list and in that we will

access the second index value that would

be 0 1 and 2 that is 6.

so this is the syntax to access an

element in a list that is already

inserted in a list

now we'll see a reverse index order for

that we'll write the command print

list 1 and in square brackets we'll

write the index minus

and we'll run this command and we get

kv as output

now we'll see slicing in python

we can access a range of items in a list

by using

the slicing operator

now we will see an example

to see

the slicing operator work in python

for that we will write the syntax print

list1

and in square brackets we'll write 1

slicing operator 3 and run the command

what we say is orange and banana as an

output from the list 1.

when you write

one ratio 3 that is one slicing operator

3 it gives you the elements at index 1

2 and note 3

so we get the output as orange coma

banana

now we will

see another example for the slicing

operator we'll write print

list 1

and in square brackets we'll write 3

and slicing operator

run the command here we can get only tv

when we write a single number before

slicing operator

it would print the value at that index

value and all the other elements that

are present in the list but in this list

we have only kv as the last element so

it would print third index value and not

more than that

now we'll see append function for that

we'll write the syntax list1 dot

append and in round brackets we will

write the element which we want to

insert at the last of the list

we will write qova and

run it and now we will print the list to

see the result

here we can see that java is added at

the last of the list

now we'll see extend function

for that we'll write the index list one

dot

extend and in round brackets

we will write

in square brackets the particular

elements we want to insert in the list

so we will write watermelon

and the next element we want to insert

would be muskmelon

that would be in inverted commas

and we also want this list to be printed

so we'll write print list one and

execute this command

here

we can get watermelon and muskmelon add

it just after the list

just at the last elements of the list

now if you want to delete a particular

element from the list you can delete it

with the syntax

dl

space

the list name you want to delete the

element

and in square brackets you will write

the index for the element you want to

delete

we have written the fifth index value

so we'll run this command

and we'll get the list printed

we can see

that the fifth index value that is

watermelon is not there in list one it's

been deleted

now

you can also do this with another method

that is removed for that we will write

list1 dot

remove and in round brackets

we'll write the particular element we

want to remove we'll write that that is

kv

and we also want the list to be printed

so we'll write

print in round brackets list one

and run this command

we get that the key is been removed from

the list one

now

there is another method that is pop

we will write that command print

in round brackets we will write list one

dot

pop

and we'll write the index value

what we want to remove from the list

that is one

and we also want the list to be printed

so for that we'll write the command

print

list one

will run this command

okay we have not written the name of the

list correctly so now list one

now

so at the one index that was orange that

has been removed from the list

and now this is the new list

now

we can see another method that is clear

that removes all the elements from the

list

so

this we would apply on the list to

list2 dot

clear method

and we'll also write another command

that would be print

list 2

and execute this command we can see that

the list 2 is empty now all the elements

from the list 2 have been removed

now we'll see another method that is

reverse for that we'll write the command

list one

thought reverse

and round brackets and we also want the

list one to be printed for that we will

write the command

print list one and execute this command

here we can see that the list one has

been reversed muskmelon

guava banana apple

now

if you want a particular index element

to be accessed you can

have the syntax for that you can write

that print

list1 dot

index

and in round brackets you just need to

write the element for what you want to

get the index

and just run this command you will get

the index of the element

guava that is one

we have another method and list that is

count so count is used to give the

number of times the particular element

is present in the list so for that we

will write the syntax print

so print

and in round brackets will write the

list name list1 dot count

and round brackets will write the

particular element

for which we want to get the number of

times that has been present in the list

write musk melon

and run this command it would give us

the value 1

because it's been present in the list

for only a single time

now let's move to the tuples

so tuple tuple is almost same as list we

can have different types of values in

tuples

the difference in list

is we can change value because list is

mutable and tuple is immutable that

means you cannot change the value

a tuple can be defined as a collection

of objects values or items of different

types and these collections are enclosed

within the circle brackets and separated

by commas

let's understand this with the help of

an example we will create a tuple and

name it as tap1 and insert the elements

in round brackets and separate them with

the help of commas

so w1 equal to round brackets the first

element is one comma and the second

element is adam third element is 107 and

the fourth element is usa

now in tuples we have our first element

at zeroth index and we have one at zero

index and atom at one index and 107 at

second index and usa at third index

and for the reverse index it starts with

minus one index value we have usa at

minus one value 107 at minus two sec

index value an atom at minus three next

value and one at minus four index value

we will explore the tuples with various

examples in jupyter notebook

but till then let's look at the

characteristics of tuple

so the first is the tuples are ordered

when we say that tuples are ordered it

means that the items have a defined

order and that order will not change

elements of the tuples can be accessed

by index

double items are indexed the first item

has index 0 the second index

has

1.

third tuples can store various type of

elements that is strings arrays and many

other elements

the next is tuples are immutable tuples

are unchangeable meaning that we cannot

change add or remove items after the

tuple has been created next is tuples

allowed duplicate elements since tuples

are indexed they can have items with the

same value

let's have a look at some methods of

tuples in python

first that is index we can use the index

operator to access an item in a tuple

where the index starts from zero

its syntax is the name of the tuple dot

index and in round brackets will write

the element for which we want to access

the index

the second is slicing we can access the

range of items in a tuple by using the

slicing operator for that we'll write

the syntax top one and the range for

which we want to slice the tuple

the third is concatenation here we will

add two tuples that is we just have to

write the name of the tuples to add them

and we'll place the plus operator just

between them

the next is repetition we can have the

same item multiple times in a tuple for

that we'll just have to write the syntax

the name of the tuple

and the multiplication operator into the

times we want that

value to be present in the tuple

the next is count it returns the number

of items a specified value occurs in a

tuple

so for that we have the syntax step one

dot count and in round brackets we will

just write the element for which we want

to count the number of times that

specified value has been occurred

we also have another method that is

indexed

it searches the tuple for a specified

value and returns the position of

that where it was found

now let's move to jupiter notebook to

explore these methods so let's start

first we will comment

that would be tuples

and we'll

move to the next column and first we'll

create a tuple

for that we'll write the command to p 1

that would be the name of the tuple and

in round brackets we'll

insert the elements that would be

apple

coma

orange

coma

banana

coma

kv

now we will print this tuple

we'll just have to write print and in

round brackets the name of the topper

and run the command

will get the tuple

printed

now

if you just want to insert a single

element in a tuple for that you will

write the command tab 2

equal to in round brackets

you will write a single element that

would be apple

and run that command

the tuple has been created but this

tuple has not been considered as tuple

in python it's been considered as string

so

let's check the type of this tuple for

that we'll write print

type

and noun brackets will write the name of

the tuple we want to check

and run this command

here we can see that it is showing a

string

so a single element is been shown as

string

in python if you want that it should be

tuple

for that you just have to

insert a single comma

in the tuple and now run this command

you will get this type as tuple

now if you want to access any element in

a tupper for that you just have to write

the command print

top one

and in square brackets the index value

that is zero

and here you quote the value apple that

is at

zeroth index value in top one

now

you can also access the element in the

reverse order for that we'll write the

command print

tap one

and in square brackets we'll write the

index value -1

and run the command here we can get the

value kv from the reverse index order

now we also have the slicing operator in

tuples also

for that we'll write the command print

tap1

in square brackets

the index values

will

run this command print top1 index value

1 slicing operator 3

so it has printed orange and banana

so what does it means it prints the

index value 1 and 2 and node 3.

we also have a repetition method in

tuples for that we just have to write a

simple syntax

like print

in square brackets the element you want

to repeat

we will write the element as repeat only

and

comma we just considered as tuple

and just

after the bracket we would have to write

the multiply operator and the number of

times the element should be repeated in

the tuple

now we'll run this command

you can see that the tuple has been

created with the element repeat and the

number of times is 3 that we have

written just after the

element

so the tuple has been created now we'll

see the count method

for that we'll write the command print

the name of the tuple

dot

count

and in round brackets we'll write the

element for which we want to

know the number of times it's been

present in the tuple

and we'll execute the command

it gives us zero

as our top one

doesn't consist

guava as an element

so it gives us the count as zero

now you see

another method that would be index

for that we'll write the command

print

top one dot

index

and in round brackets we'll write the

element for which we want to fetch the

index of that element

banana and we'll run this command

we will get the index of the element

banana that is 2

0 1 2.

so we get the index of the element

banana

now if we want to use the append method

in tuples we have to first create the

tuple into the list for that we'll write

the command y equal to list

and in round brackets we will write

the name of the tuple

which we want to convert in the list

now we will use the append method

to the list that is why

put append

and will insert an element that would be

cova

and now

we would just assign

the y list to a variable top one

we have now converted

the y list to the tuple with this syntax

that is

tuple y and we have assigned it to the

top one value

now we'll print this tuple

and execute the command here

we can see that we have used the append

method

in the tuple

first we have changed the tuple to the

list

by this command y equal to list tab one

then we have used the append method y

dot append

and appended the element cover

then we have changed the y list to the

tuple that is stuff one equal to tuple

the name of the list and then we have

printed the tuple

we can also add two tuples by another

method

for that

we will

write another tuple that would be top

three

equal to we will insert an element that

would be

cherry

and now

we want

it to be added in top one so we'll write

top one plus equal to

top three

and now we'll

print

the final tuple that would be top one

and run the command here we can see that

we have added

two tuples that is tuple one and tuple

three which consists of cherry and here

we get the whole tuple as double one

now

to execute

loops in tuples we'll write the command

for that we'll write the syntax

for

space

a variable x

and

the name of the tuple

colon

and then we will print

the particular element one by one and

we'll run this command here we can see

that all the elements have been printed

from the tuple

now let's understand dictionaries in

python

in list you can fetch the elements with

the help of index numbers what if you

want to specify a different type of

index for it example if you have a list

of eight values and you want to fetch

the fifth one you will use the index but

if you have key for each element then

you can use the key to access that

element example phone book if you want

to fetch a number you will use a name

and you get a number and officially if

we talk about dictionary if you want to

understand the meaning of a word you go

to that page and you look at the word

and understand the meaning of it so this

type of concept where you have a key and

corresponding to that you have a value

we can achieve this with the help of

dictionaries

python dictionary can be defined as a

collection of objects values or items of

different types stored in key value pair

format these multiple key value pairs

created are enclosed within the curly

braces and each key is separated from

its value by the colon let's understand

this with the help of an example

dict 1 equal to curly braces the first

key is a and corresponding to that we

have value and that is separated by

colon and after the key value pair that

is separated by a comma

the next is b key and that has a

corresponding value too

after that we have inserted a comma

to separate it from other values now we

have a third key that is c and

corresponding to that we have a value 3.

let's see some characteristics of

dictionaries

the dictionaries are ordered from python

version 3.7 when we say that

dictionaries are ordered it means that

the items have a defined order and that

order will not change

second that is elements of the

dictionaries cannot be accessed by index

third dictionaries can store various

types of elements

fourth dictionaries are mutable

dictionaries are changeable meaning that

we can change add or remove items after

the dictionary has been created

fifth one is dictionaries doesn't allow

duplicate elements dictionaries cannot

have two items with the same key

now let's see some methods in

dictionaries

the first is clear method

it removes all the elements from the

dictionary and its syntax is the name of

the dictionary dot clear

the second is get

it returns the value of the specified

key

the syntax is dict1 dot key and in

square brackets we have to write the key

name

the third is keys it returns a list

containing the dictionaries key

its syntax is dict1 dot keys

the next is pop it removes the element

with the specified key its syntax is

dict1 dot pop

and in round brackets you would write

the particular key name

and the next method is pop item it

removes the last inserted key value pair

from the dictionary and its syntax is

dict1 dot pop item let's move to the

jupyter notebook and execute these

methods

first we'll add a command that would be

dictionaries

and now we'll create

our dictionary

for that we'll write the syntax name of

the dictionary

equal to

curly braces

first we will write the key value

then colon

and the value corresponding to it

will write apple

then separate it by comma

and then the second key value

colon

and

the value corresponding to that key

that would be orange

when it would be separated by comma then

we'll assign another key value that

would be 3

colon

and

the value corresponding to that would be

banana

comma

next with

the key value would be 4 colon and in

inverted commas we'll write the value

corresponding to it

and we'll print this dictionary

print text one and execute this command

here we can see that the dictionary is

printed

with one key value we have the

corresponding value apple with 2k value

we have the corresponding value orange

with 3k value as the corresponding value

banana and with 4 key value we have the

corresponding value kv

now to access a particular element

we can't do that in dictionary but we

can access a particular value with the

help of key we can do that in dictionary

for that we would write the syntax print

the name of the dictionary

and in

square brackets we'll write the key

value that would be 1 and run the

command would get the value

corresponding to the key value

that is apple that is corresponding to

the key value 1.

now

we will see a cat method in dictionary

for that we'll write the command print

name of the dictionary dot

get

and in round brackets we'll just write

the key value

and run this command we'll get the

corresponding value to the key value

that is apple

now

we will use another method that would be

pop for that we will write the command

print

deck 1 dot

pop

and in round brackets we'll write the

key value

for the value

we want the element to be removed from

the dictionary

we will execute this command

and we get kv as the output now if we

print the dictionary

print dict 1

we can see

that the fourth key value and the value

corresponding to that key value has been

removed by the pop method

now

we can also print the length of the

dictionary for that we'll write the

command print

len

and in

round brackets we'll write the name of

the dictionary

and just execute the command we will get

three as the output as it has been

considered one unit second unit and

third unit so the length is three

and we have

another method that is sorted for that

write the command print

sorted

and the name of the dictionary

dict 1 will execute this command

it would give us all the key values in a

sorted manner

when executed with this command

now we can see another method that is

keys for that we have to write the

command print

round brackets name of the dictionary

dot

keys

round brackets

and we'll run this command and we'll get

all the keys that are present in

dictionary

there is another method that is values

for that we'll write the command print

deck one dot

values

round brackets and we'll execute this

command

we'll get all the values that are

present in the dictionary now we'll see

another method that is update

that is used to update the particular

value corresponding to the key value or

update the dictionary with

more values to be inserted in the

dictionary

for that we'll write the command dict1

dot

update

in round brackets first we'll

write the curly braces

the key value

semicolon colon

and corresponding to that will write its

value which you want to update

watermelon

and we'll also

print the dictionary

we'll execute this command we will get

that the

second value that is watermelon that's

been updated

previously it was orange and now it's

watermelon

so it's been updated by this command and

we can also use this command to add more

elements to the dictionary

for that we'll write the syntax dict1

dot update

round brackets curly braces

and the key value colon corresponding to

that

we will write the value

muskmelon

and we will print the dictionary

and we'll execute this command

sorry we just

commented the name of the dictionary

dict one dot update

now we will execute this command

here we can see that the value has been

added to the dictionary

now we'll see another method that is pop

for that we'll write the command dict 1

pop and in round brackets the key value

for which we want the value

to be removed from the dictionary and we

will print the dictionary

and execute this command

here we can see that the second key

value has been removed from the

dictionary

and we will see another method that

would be text one

dot

pop

item and then we will print the

dictionary

and execute the command

here we can see that the pope item has

removed the last element from the

dictionary and we are left with only two

elements in the dictionary

now

we will see some loops in the dictionary

for that we'll write the command for

x

in the name of the dictionary that is

text one

colon

and then we will write print

dict one

and in square brackets

the variable x and we'll execute this

command

so with this loop we can print all the

values corresponding to the key values

in the dictionary

now to print both the

even values corresponding to it we can

run a loop for that we'll write the

command for x comma y

in

dict1

dot items

colon

print

x comma y

and run this command

we can get the key and the values

corresponding to it

now if you want to copy the particular

dictionary in another dictionary you can

write the command

first you will name the dictionary you

want to create and copy the elements

we will name it as my dict

equal to

now i will write the command dict 1 dot

copy

and then

we will print the new dictionary

that is

my

dict we'll run this command

okay we have

not inserted the wrong bracket here now

then this command here we can see that

we have printed the my dick dictionary

and it has the same values as dict one

now

we'll see another method

to delete

the whole dictionary

for that we'll write

text one dot

clear

it would remove all the values from the

dictionary and will also

print

the dictionary after that

then this command here we can see all

the elements from the dictionary have

been removed

so what is list comprehension

in python programming list comprehension

provides a short as syntax

when you want to create a new list based

on the values of an existing list

so you can build a new list with a

compact syntax based on the values of

the existing list using python

programming

now you can define a list comprehension

inside the square brackets and execute

each element using a for loop that will

iterate over all the elements

now below you can see the syntax of

writing a list comprehension i have my

variable declared as new list that will

store the list comprehension

so using square brackets i have

mentioned expression

and i'm using the for loop which is

going to iterate over all the elements

in my

old list and after that i have my if

condition

now let's look at the advantages of

using list comprehension

so it helps to accomplish your task with

fewer lines of code

now it is more time efficient compared

to running multiple loops for the same

task

and you can use iterative statements

that appear as formula now let's head

over to our jupyter notebook where we'll

learn list comprehension in detail

so i am on my jupyter notebook so let's

start with our first example

suppose you want to

find the squares of all the numbers that

are present inside a list

now let me show you the traditional way

of solving this problem

so first of all i'll declare a

list called num

and within square brackets i'll

have some numbers let's say 1 2 3 4

and now

i'll create an

empty list called sq that will

hold the

squares of my four numbers that i have

put

so i'll say for

n which is my iterator variable in

my list num i'll give a colon

and then i am going to

append the squares to my variable called

sq so i'll write sq dot

append

and to get the squares i'll say n

i'll use the

double asterisks operator to get the

squares i'll say double asterisks 2.

now

i'll just say print sq

if i run this i get the result which is

fair enough so the

squares of 1 2 3 and 4 are 1 4 9 and 16.

now

the same task you can do using

list comprehension in just

two lines

first of all i'll just declare my list

again say num

which will have the values 1 2 3 4 and

let's say 5.

now i'm going to write my list

comprehension

like this i'll say sq equal to

i'll have my expression

which is going to be n

asterisk asterisks 2

then i'll say for

my iterator variable n

in my list num that's all

so this is how you can write a

list comprehension method

and then let's print

sq

now if i run this

we get the same result you can see the

squares of 1 2 3 4 and 5 are 1 4 9 16

and 25

so

this is a simple example how you can use

list comprehension in python it is very

short and you can write

the same

task in a very compact manner as you can

see here

cool

now moving ahead let's say you wanted to

print all the letters in the word simply

don't

so for that

let me show you how to

do it in a traditional way first

so i'll create a

empty

list called let's say n underscore

letters

i'll just give square brackets so this

means

your end underscore letters is now

an empty list so i'll say for my

iterator variable letter in

my

word that is

simply learn i'll give a colon

then i'll say

n underscore

letters

dot

append

my data variable letter

now let me print

and underscore

letters

if i run this

you see here we have

printed all the

individual letters that are present in

the word simply learn

now the same task you can do using

list comprehension in just one line

so create a variable called end

underscore letters

and then i'll write my syntax as

letter for

letter in my word simply learn

and then i'll just say print and

underscore letters

run this there you go

you can use the

list comprehension technique to

implement the above task in just one

line all right

now moving ahead

we'll see how to use

a for loop

and

we are going to display

the cars

that are present in a list and have a

letter s in it

so first of all i am going to

declare a list called cars

and it will have

the names of a few cars let's say we

have

jaguar

then we have

land rover

next let's say we have

tesla

after that let's say we have

toyota

and then we have

tata

now

i'm going to create an empty list called

new list

i'll just give

square brackets

now i'll say for my i treated variable x

in

my

list cars i'll say if

we have the letter s in

x

then

i'll say

new list dot append

x

after that i'm going to say print

new list

so what

these lines of code will do is my for

loop is going to iterate through each of

the elements that are present inside the

list cars and will check if any of the

car brands have the letter s it is going

to print

that car brand

if i run it you can see here

we have tesla which has a letter s in it

the rest of the car brands don't have

the letter s and hence we have got tesla

now the same

task you can do using list comprehension

i'll just copy this line of code because

we are going to use the same car brands

and the same

list name called cars

now i'm going to write my

list comprehension technique i'll say

new list equal to

as x for x in

cars

if i'm going to use the if condition now

i'll say s

in

x

now let's go ahead and print my

new list but on this there you go you

can see that we have tesla printed

now let me just change this s to

small a or lowercase e

if i run it

you see here

all the five brands of car have the

letter

small a you can see jaguar has it land

rover also we have small a tesla has

small a

we have toyota

and tata as well now what if i change

the name of data to all upper case

so i write d8ta all in uppercase now if

i run this

there you go

since python is case sensitive

and here we are checking only for

lowercase a so we did not have

data in our result since we converted

into an upper case

all right now moving ahead

i'm going to show you how you can

filter

only those values and a list of integers

that are greater than 50.

so i'll say

new underscore list equal to

i'll say

x for x in range

i'm using the range function so i want

to print the list of integers

the first hundred integers

and i'll use my condition f

x is greater than 50

now let me go ahead and print my new

list which is new underscore list

but on this there you go

so here you can see

our

range is from

0 to 100

which means from 0

till 99 you can see it here

but we are only trying to print only

those integers that are greater than 50

so we have values from 51 till 99

suppose i'll change this to

let's say less than

45 or let's say less than 30

and if i run this

you see here you have all the integers

present between 0 till 30

cool

now moving ahead

let's see another example i am going to

use the same list which we had

declared before that is the list of car

brands

now

i am going to

print

all the car brands

if it is

not tesla

but if the car brand is tesla we are

going to change this to let's say audi

now let me show you how to do it using

list comprehension

i'll say

new underscore

cars

equal to

i use the square brackets i'll say x

if

x

not equal to so i'm going to use the

exclamation mark equal to

tesla

then

we should print x

else

i'm going to use the else clause as well

and say else

if the car print is

tesla then changes to audi

and i'll say for x in

cars

now let me go ahead and print new cars

there you go

so

since all these elements were not tesla

so we printed the car brands as it is so

jaguar land rover toyota and

tata

now since

we encountered one tesla here so

with the help of

list comprehension we changed tesla to

audi

cool

now moving ahead

so using function will print true for

even numbers and false for

odd numbers let me show you how to do it

so i'll create a

empty list called numbers

so this is an empty list

now i'll say for i in

range

let's say i'll set the range to 0 comma

20 i'll give a colon

i'll say

numbers dot

append

i'm going to give my condition

i

percentage 2 should be equal to equal to

0 so this means

within the range 0 to 20 i am checking

for numbers that are divisible by 2 so i

am seeing if the

reminder is 0

then i'll say

print

numbers

now let me run it

there you go

so there are total

20 numbers starting from 0 till 19

now

wherever the number is

even we are printing true else we are

printing false so this number starts

from the zero

place so

we have 0 as true 1 is false again 2 is

true because 2 is an even number 3 is an

odd number so we are false 4 is an even

number we have true so here

5 is an odd number so we have false so

on and so forth and the last 3

so 17 is an odd number so we are false

18 is an even number we have true and 19

again is an odd number so we have false

all right

now moving ahead

we'll see

another example

let me create

a variable called numbers

i'll say

i

percentage 2 equal to equal to 0

for

i

in

range

0 comma 21

let's print numbers and see the result

so here you can see we have the

same result this time

using

the list comprehension technique

now coming to the

final

example in this demo this time i am

going to create a four course four

matrix using the numpy library in python

and from the matrix we are going to find

the maximum element present in

each of the rows

so let me first import my

numpy library i'll say import numpy as

np

i'm going to

create a matrix

that will have random integers so i'm

using the

random module and inside that we have

the random function

i'll say

let's say

10

so i want the numbers

within 10 and i'll set the size to

4 comma 4

i'll say

print a now if i run it

you see here we have our

randomly generated 4 cross 4 matrix

where the elements lie within 0 to 10.

now from this randomly generated matrix

i am going to find the

maximum elements

so i will say max element equal to

i am going to use the list comprehension

technique so i say

max of i

for

i in

my matrix a

let's print max element

if i run it you see here the maximum

element from each of the rows so in the

first row we have eight as the maximum

element and then in the second row we

have

again eight as the maximum element

in the third row we have seven as the

maximum element and in the fourth row we

have eight again

now if i run this again my

randomly generated matrix changes

now if i run it you can see 5596

are now the maximum elements

cool

so we are going to look at what is a

function in python then we will see the

different types of python functions

then you will understand the various

advantages of using python functions and

finally we will head out to our jupyter

notebook to understand python functions

in detail with hands-on demonstrations

okay

so what is a function in python

so a function is a bunch of statements

that are defined to perform specific

operations

a function in python helps to divide

your program into smaller and modular

chunks thus allowing you to make

extensive programs more organized and

manageable it also avoids repetition and

makes the code reusable

so let's understand the types of python

functions first we have

built-in functions so these are the

functions that are built into python

so by default the inbuilt functions are

available in python then we have user

defined functions so functions defined

by users to carry out certain tasks are

called user defined functions they don't

have a fixed name

so here on this slide you can see the

different built-in python functions that

are available so you have power length

next max absolute we have print range

slice sorted round and there are many

more so these we will explore in our

demo session

so wait for a while

now

let's understand about the user defined

functions so these functions are defined

by users to perform specific tasks

and

these are the steps that you need

to create a user-defined function so

first you need to create the function

and then call the function

now moving to the

next slide so here you can see the

syntax of writing a user defined

function so we use the def keyword to

define the function followed by the

function name and within brackets you

have the parameters or the arguments of

the function

then you have the function block

and if you want to return a value from

the function you can use the return

function followed by the expression

so here is an example where we are just

printing hello python using a user

defined function and in this case my

function name is called my underscore

function if i call my underscore

function it will return me hello python

cool

okay

now let's understand the advantages of

using

python functions

so with the help of functions you can

avoid rewriting the same logic or code

again and again in a program

so in python you can call functions

anywhere multiple times in a single

program

you can also track an extensive python

program easily when it is divided into

multiple functions

and the most crucial feature or the

advantages of python functions is that

of its reusability

cool now let's head over to our jupyter

notebook and we'll explore the inbuilt

and user defined functions in detail

okay so i'm on my jupyter notebook first

i'll go ahead and

rename my

notebook as functions in

python

i click on rename

okay

first of all let me just increase the

size

okay

i'll give my comment

as built-in functions

okay

so we'll start by looking at the

absolute function in python

so absolute or abs function returns the

absolute value of a number

so i'll say let's say e equal to

i'll use the absolute

function which is represented as ebs in

python

suppose i write

abs of let's say 10.75

and if i print a

it gives me 10.75 which is fair enough

let me just copy this code i'll paste it

here

i'll say b equal to aps

this time i am going to use the

negative symbol or the negative sign

i'll say minus 10.75 and will print b

let me run it you can see here

python has automatically removed

the negative sign and it has just given

us 10.75 so this is how the absolute

function

works so abs returns the absolute value

of a number which is always positive

now let's see another inbuilt function

very popular which is called the length

function or len i just give a comment

saying len

above also let me just give a comment as

aps

okay

so later we can have a track of whatever

functions we have learnt in the demo

so the length function returns the

length of an object it could be an i

table such as a list it could be a tuple

or even a dictionary let me show you how

it works i'll say

list 1

equal to

i'll create a list within square

brackets let's say

i have

a few letters

let's say

i n then i have

d

i again

and a

so i have

all the letters in my word india now if

i say x equal to

ln of list one

then i'll print x

it gives me five because the length of

all the characters in my

list

is 5 you can count here i and dia

so there are only 5 elements and hence

it is written as 5.

now we'll explore another function which

is called as all

so the all function returns true if any

item in an iterable object is true

so i'll say

my underscore list

equal to

let's say i have

0

1 and 0

i'll say x equal to

then i'll use the all function

and inside the function i'll pass in my

list which is my underscore list

and will print x

hold on for a second and can you please

guess what this

x will be

it gives us false the reason being

we have

two false values 0 and 0 here and there

is only one true value which is 1

suppose i had 1 1 and 1

if i run this it would have given us

true because all the elements in my list

or the i triple are true

if any one of the elements is false it

will give us false

okay

now moving to our next function which is

called sum

so python sum function is used to get

the sum of numbers of an i table

let's say i have

s equal to

i'm using the function sum

and inside the sum function i'm going to

declare a list of numbers let's say we

have 20

35 and let's say

70

let me create another

list called

s1

i'll say sum

and now

let's say we'll pass in a tuple now so

i'm using another

bracket

we have let's say

7 5 and 9

now if i write

print

s

and let's say i want to print s1

you can see here

my sum function has

returned the sum of all the numbers in

the i treble the first one was a list

and next we have a tuple so

20 plus 35 plus 70 is 125 and then

7 plus 5 plus 9 is 21 so this is how the

sum function works

moving ahead we have the

max function next

as well as the main function

so as the name suggests the max function

will return the maximum number of an

iterable

so i'll create a variable called m1

and i'll use the max function

let's say we have a few values 7 10

3 12 61 and

40.

now let's go ahead and print m1

now if i run it

it returns me the maximum number that is

present inside my list of numbers or the

tuple that i have passed in

here you have the maximum number as 61.

now let's use the max function over a

dictionary so i'll create another

variable called m2 and i'll say

max

and inside the max function i'm going to

pass in my values in the form of a

dictionary so i'm using curly brackets

or braces

i'll say let's say 7

90 we have 3

let's say 150

67 and 44.

now let me go ahead and print m2

if i run it you can see it here it has

given us 50 which is the highest element

in my

dictionary

okay

now similarly you can use the

main function let me just copy this

and i'll paste it here

i'll say m3

instead of max function we are going to

use the main function so the mean

function will return the

minimum number in an i table

let's say i'll pass in

m3 as a

list this time and if i say print m3

it gives me three which is the lowest

number of the lowest value in my list

and similarly you can

have the lowest value printed from a

dictionary i'll just

change the variable to m4

and instead of max will use

the min function

and here also i'll use the

variable as m4

if i run it you can see here

we have printed the

minimum value in my dictionary which is

three

okay

now moving ahead

we'll explore another function called

iter

so python item function returns an

iterator for the given object so the

iter function creates an object which

can be iterated one element at a time

and the next function returns the next

item in an iterator let's use both iter

and next function in our next example

so i'll create a list called my list

and

is equal to

followed by using the iter function and

inside the item function i am going to

pass in a

list which will have

letters of india

i have n

d

i

and then i have a

now

i'll create another variable called x

and then i'll pass in the next function

and inside the next function i'll pass

in

my list and

we'll go ahead and print x

so

it will print the

first

element in my

iterable that is i here

if i copy this

and i'll

paste it here if i run it again

you can see it here the iter function

returns the

second i table which is n in my list i n

d i a

i'll paste it again if i run it

we have the

third item in the list which is d

okay

now coming to using the

power function in python so python pow

the power function returns the power of

the given numbers

let's say x raised to the power 3

so i'll

declare a variable x1 and say pow

let's say i want

the value of 3 raised to the power 3

and let's say i have another variable

called x2

i'll use the pow function and this time

i want to know what is 2

raised to power

4.

we'll go ahead and print x1 and x2

and as you guessed it 3 raised to the

power 3 or 3 cube is 27 and 2 raised to

the power 4 is 16.

cool

now coming to using the range function

so the python range function returns a

sequence of numbers starting from 0 and

increments by 1 so this is by default

and stops before the

given number

so let me show you

if i say x equal to i'll use the range

function and inside the range function

i'll have my value as 6

then i'll say for n

now here n is my iterator variable

i'll say for n in x

print

n

let's run it and we'll see the result

you can see here the range function has

returned us the numbers starting from

zero and it has gradually incremented

the

iterator by one so we have from zero

till five

now i'll show you another example

i want to change

the default starting value that is 0 so

i will save

x equal to

range i'm going to start from 40

till 50

with a step size of 2. so you can pass

it as the third argument so it will skip

one value and print the next value so

then i'll say for n

in

x i'll give a colon

let's print n

and we'll see the result you can see

here it starts

with 40

and has a step size of 2 so we have 40

42 44

46 and 48 cool

now let's move ahead and we'll explore

the

round function in python

so the round function rounds off a

number to the given number of digits

let's say i have x equal to i'll use the

round function

and then i'll have a decimal value let's

say

eight point six

two

four

seven five

and i want to round it to two decimal

places

let's print x

if i run it you can see here my

python has returned a rounded up value

to two decimal places so we have

8.62 and the rest it has just skipped

moving ahead we'll explore the

sorted function in python so the sorted

function returns a sorted list of the

specified iterable object you can

specify ascending or descending order

so i'll create a list called a

and we have

the elements let's say again india so i

have i

n

d i

and i have e again

if i say x equal to

sorted a and

if i print x

you can see it here python has sorted

the elements in the list in

ascending order of the

letters so we have a appearing first

then d again i and i and then finally we

have n

now

suppose you wanted to print the letters

in descending order

you can use another argument here i'll

give a comma and say

reverse

equal to

true

so this

line will ensure

my list is sorted in descending order

you can see here it has just reversed

the above result so we have n appearing

first and i i d and e

you can do the same for a list of

numbers let's say we have 12

50

38

76

let's say 27

80 and 5.

i'll say x equal to

sorted a

and will print x

if i run it you see it here we have

sorted the numbers in the list in

ascending order now

if you want to sort it in descending

order just add reverse equal to true

there you go here

my list has now been sorted in

descending order of elements

now we are going to look at the final

built-in python function which is

slice

so the slice function returns a portion

of an iterable as an object of the slice

class based on the specified range

suppose i have

a list called a

okay let's not define a list we'll

define a tuple

so this has the letters

in the word simply learn

so i have s i m

p

l

i

again l

i have e

comma i have a

then we have r and finally i have n

so these are the letters which have been

represented as a tuple

simply learn

then i'll use the slice function

and

i'll give my range as 5 and will print

a of x

let's run it you see it here

the slice function has sliced the

first

five elements in my tuple so we have s i

m p and l

cool

so we have explored

all the important

built-in python functions

now let's head over to using

defined functions or learning user

defined functions in python i'll give a

comment first user defined functions

cool

so as we had learnt in our slides

to define a user defined function we

will use the def keyword

and

a function name this should be a valid

python name so i'm using func one

followed by parentheses and then we'll

have a colon

and now we'll define the body of the

function i'll say

print

hello world

this is the same example that we had

seen in our

slide

now

i am going to call the function

using the function name which is

fu and c1 if i run it you can see it

here

i have my message printed hello world

so this is a very

simple

user defined function

and it does not

carry any arguments or parameters

now let me show you another

user defined function i'll say def

hello

again we are not giving any parameter

to this function or arguments to this

function

i'll say

name equal to

str this time we are going to take the

input from the user so i'm using the

input function i'll say

enter your

country name

give a

colon and a space

and then we'll say

print

i'll print the message

hello

followed by a space

give a plus sign

and we are going to convert our name to

string

so this is my function let me run it

now i'll call hello

it is asking me for

entering

country name i'll say japan

if i

hit enter it says hello

then

my country name which is japan so hello

japan

let me run it again this time i'll say

usa

i'll hit enter you can see here my

message is hello usa

cool

now moving ahead to our next example

where we'll see

using functions with

different parameters

so we'll start with a very simple

example

i'll say

def

i want to convert

feet to centimeter

i'll say my function name as ft

underscore 2 underscore cm

so i'll pass in a

value for feet and that feed will be

converted to centimeters

and this time inside parentheses i am

going to pass in

my parameter as f t

i'll use the formula for centimeter i'll

say

my variable centimeter equal to

feet

multiplied by

30 point

so 1 feet is actually

30.48

centimeters so centimeter becomes feet

into 30.48

then we are going to use the return

keyword and i am going to return the

output which is

centimeter

let's run it

now to call the function i'll use my

function name which is ft underscore 2

underscore cm

this is my function name

and then i'm going to pass in a

value for feet let's say i want to

convert six feet

into centimeters if i run it there you

go you can see it here

6 feet is actually

182.88 centimeters

let's see

5.8

if i run it it is

176.7

centimeters

so here you saw how to pass in arguments

to a user defined function

now again you can pass in multiple

arguments

let's say

i'm going to find the sum of two values

for that i'll create a function called

tef

my function name is add i'm going to add

two values x and y

so i'm passing in

two parameters x comma y

i'll create a variable called sum that

will store the value of x plus y

and then let's print sum

okay let me just scroll down

i'll hit shift enter to run it okay we

have created my function

that is add now let's add

40

and

50.

you have to pass in two arguments

because we have

declared

x and y in the function so it needs at

least two arguments if i run it you have

the sum of

40 and 50 which is 90.

let's say i have

minus 20 and

30 if i run it you have the result

minus 20 plus 30 is

10

all right

now similarly you can also multiply two

numbers let me just copy this

i'll

paste it here

and instead of add

i'll give my user defined function name

as

multiply

i'll say

product equal to x

asterisk y and i'll print

product let's run it

i'll call my function using the function

name multiply let's say

4

multiplied by 6

so the result is 24

cool

now moving ahead

we will explore another example let's

say i want to print the absolute value

of a number

so i am creating a function called def

my function name is absolute and i'll

pass in

one parameter which is x

i'm going to use

i felt's statement i'll say if x is

greater than or equal to 0

i'll give a colon

then i'll say return x

else

give a

colon i'll say return

minus x

i'll run it

now if i print

absolute

of let's say

56

the result is as expected since 56 is

greater than 0 we have just returned 56

let me just copy this

i'll paste it here let's say absolute of

minus 56 is again 56 because we are

returning

minus x so minus of minus 56 becomes

plus 56

now if you wanted to return minus 56

you need to

make some modifications i'll put another

minus and keep this within brackets let

me run the function again

and now if i print absolute of minus 56

you have the result as -56

okay

now let's see another example how to

find the factorial of a number using

a user defined function so we'll define

our function as def i'll use the

function name as factorial

i'm going to pass in a

parameter called x i'll say if x is

equal to equal to 0

then we'll just return x or return 1.

i'll say

else

give a colon

return

i'll say x

asterix or multiplied by i'll use the

function name factorial

i'll say x minus 1

now let's run it

i'll call my function

factorial

let's say i want to find the factorial

of 5 the result is 120 let's say the

factorial of 10 the result is

36 lakhs 28

800

cool

now let's see how you can pass in

default arguments to your function or

default parameters

okay

suppose

i have

a function defined called welcome

here i am going to pass my argument

as name

and in the argument itself i'll pass in

the value a default value let's say paul

give a colon and i'll print

hello

this would be within

quotes

and the

name

cool let me just run it

now i'm going to call the function

welcome

this time i'm not giving any value to my

function if i run it it has

automatically taken the default argument

which was paul so my message becomes

hello paul

now

let's say i'll pass in

a value

welcome

and within quotes i'll say c

now the message becomes hello ac so if

you pass in

a value to your

function welcome

explicitly it will take that value

instead of the default argument

cool

now you can also have multiple arguments

in your

function as we saw above for the

addition and multiplication

functions

i'll create a function called

message

and we'll have

the arguments as name 1 name 2 and name

3

give a colon

i'll say

print

a message that is

hello

and give space give a comma

we have name one

give a comma and then i'll say

comma

please

tell

give another comma

i'll have my name 2

give a comma

followed by the message that

then i have name 3

this should be a comma instead of a

period

then i'll see is

waiting

make sure this is within quotations

again

just keep a exclamation mark

okay

so i have my message let's run it

now i'll call my function

message

we need

three arguments now so i'll pass in

three names let's say my first name is

gilly my second name is rachel

and my third name is let's say shaw

i'll run it and you can see here we have

my

message printed hello followed by name

one which is kili so hello ghillie

please tell name to which is rachel so

please tell rachel

that

name three which is shaw that saw is

waiting

cool

now we'll understand about

scope of variables in a function

now your scope could be a global scope

or a local scope let's

define a function called

func

3

inside the function i am going to create

a variable called

z which has a value of 7

now i'll just print

z

and i'll call in my function

3

if i run it you have the value printed

of z that is 7 now if i want to access

my variable that is z outside the

function if i run this

it throws me an error because

this

variable z was defined locally that is

inside the function and you cannot

access z outside the function

now to overcome this issue let me just

copy this

we are going to declare z

as a global variable

so i'll have z outside the function i'll

say

z equal to 7 and then i have

my function defined i'll just change the

name of the function to

function 4

and then we'll

print z and i'll call the function

function 4

if i run it

you can see it here i have the

value of z printed that is 7. now if i

want to access z outside the function

then also it's fine because we have

defined z

outside the function that is

z is now a global variable so its scope

is throughout the function

now another thing to note here is you

can't change the value from

inside a local scope

so

if i say z equal to 7

and then i'll define my function f u n c

let's say 5

i'll give a colon and i'll say let's see

i want to alter the value of z to let's

say z plus 7

i'll print

z

and let me now call

func5

if i

run this

it throws me an error

as i said it says local variable z

referenced before assignment

so you can't change its value from

inside a local scope for that you're

going to explicitly define the variable

z as global let me show you how to do it

i've just copied this code and paste it

here

i'll say

z equal to 7

i'll define my function let's say if you

nc

6

here i'm going to say

global

c

so i've explicitly defined my z as a

global variable

now if i

call the function 6 you can see here we

have altered the value of z from 7 to z

plus 1 that is 7 plus 1 which is 8.

okay

now asterix arcs in function definitions

in python are used to pass a variable

number of arguments to a function

suppose you don't know the exact number

of arguments you need so you can use

the argument with an

asterisk symbol let me show you how to

do it

i'll say def welcome

and

here i'm going to pass in

asterix followed by the

name of my argument which is names

i'll say print

i'll print my message as hello

comma

then i'm going to say

names

the first name which is with

index value of 0

comma

followed by a space

then i have

name

one

will give a

comma followed by a space and then we'll

have

names

two

this should be names

okay let me run this

now i'll call my function welcome

now you can see here i have passed in my

argument that is names three times so

let's

call three names let's see we have steve

then we have

bill

and then we have let's see yes

now if i run this

there you go we have a message printed

hello steve bill yes

okay

now coming to the final section of our

demo

here we are going to find out the area

of a circle and a sphere so we are going

to define two functions one for circle

and another for spear

so first of all let me define the value

of pi which is 3.14

i'll start

with def

i'll give my

function name as circle area

and inside that i'll pass in my argument

that is radius

i'll give a colon and we are going to

return the area of a circle

which is pi

r square so i'll have

radius

again an asterisk symbol and then radius

so this becomes pi

into radius into radius which is pi r

square

okay now let's define another function

called def i'll say

sphere

area

i'll have my

argument as

radius

give a colon

and say

return

4 pi r square which is the area of a

sphere so i'll have 4 multiplied by pi

multiplied by

radius multiplied by radius so this

becomes 4 pi r square

now we are going to define

the main function so i'll say define

mean

where we'll just have

our print statement so i'll say print

circle

area

with

radius

15

i'll give a

comma

and say

circle area

which is my function name

and we'll pass in the value of the

radius which is 15

i'll just copy this message

and we'll print it here i'll say

spear area

with radius 15 as

i'll just change this to spear

and let's see we'll have radius for 10

instead of 15

okay

finally i'm going to call my main

function so i'll just say

main

now let's run it

okay there is one error here

this is an indentation problem now we'll

run it again there you go

so the circle area with radius 15 is

3.14 which is the pi value multiplied by

radius into radius that is 15 into 15 so

the value is 706.5

and similarly the

spear area with radius 10 is 4 into 3.14

into 10 into 10 that is

1256

all right so what is the lambda function

a lambda function

is one of the simplest ways to define a

function in python a lambda function is

an anonymous function defined without a

name and does not have the def keyword

it can accept any number of arguments

but can only have one expression

so the function is always defined using

the lambda keyword which you can see it

here

so here we have the syntax for lambda

function we use the lambda keyword

followed by the arguments and then we

have a colon after that we have the

expression that we want to evaluate

cool

now moving ahead let's

look at an example of using lambda

function in python

now

if you were to add two numbers in python

using a function you would ideally use

the

def keyword followed by the

function name and then pass in the

arguments you can see the arguments here

a and b

then

use the return statement to get the

value of the addition so we have written

a plus b

and finally you will call the add

function and pass the argument values to

get the result

now this operation can be done using the

lambda function as shown here so we have

defined a variable called add which is

equal to and then we have used the

lambda function followed by the two

parameters or arguments so here a and b

are the arguments and then i have my

expression a plus b see all this you can

do it in one line

and then to call the function you use

print

followed by the variable which is add

and then you have the arguments 3 comma

8 so the addition of 3 plus 8 would be

11.

now you can see that instead of using

the df keyword we have used the

lambda keyword and there is no

parenthesis required anything after the

lambda keyboard is treated as a

parameter or argument

so

we use a colon to separate parameters

and the expression in our case the

expression is a plus b

now moving ahead we look at

the pros and cons of

lambda functions so lambda functions are

suitable for simple logical operations

so when we want one expression in return

we can use the lambda function a lambda

function is used as a parameter to

different functions such as map filter

reduce we will see all this in our demo

session

now coming to the cons of using

a lambda function

so

lambda functions can only evaluate one

expression as i told you earlier

you cannot write a docs string to

explain all the inputs operations and

outputs as you would do in a normal user

defined function that uses the df

keyword

and finally lambda functions are

generally not preferred when you have to

declare a function with multiple lines

of code

now let's head over to our jupyter

notebook where we will learn about

lambda functions and how to use it in

different ways

so i'm on my jupyter notebook let me

just go ahead and we'll

rename the notebook as

lambda

functions in python

okay i'll just click on rename

cool

first of all i'll write a

general user defined function using the

def keyword let's say i want to add two

numbers

so this example we have already seen in

our slide

so the way to do is i'll use the df

keyword followed by the

function name

and then i'm giving my

arguments or the parameters

after that

let's say i want to store

the addition of a plus b in a variable

called result so i'll say result equal

to e plus b

and then

i want to return my output that is

result so i'll say return result

so this is how you will normally create

a function in python

if i run it and then

i'm going to call my function using the

function name that is add and then i'll

pass in

my parameters a and b let's say my a is

3 and b is 4.

if i run this

i will get the result 7 which is fair

enough

now if i want to

do the same operation using

a lambda function i would do something

like this let's say i'll create a

variable called add

and then i'm going to use the lambda

function

followed by the arguments

a comma p

then i'll give a colon and say a plus p

after that i'll just say add

and then pass in my parameters

3 comma 4 if i run it you have the same

result that is 7.

now let's see another example using

lambda functions to add

a number this time i am going to pass in

only one argument

so i will say add equal to

lambda

my argument is x i'll say x colon x plus

let's say i want to add x with

100

i'll say

print

add let's say i want to add 50 with 100

if i run it i have the result 150

all right

now in python there is no need to assign

a lambda to a variable you can directly

call it let me show you how to do it

i'll say

lambda

a comma b which are my arguments

again this time i am going to use

a multiplication

operator

since i want to do a

product of a and b

and after that

using another parenthesis you can

directly pass in the

arguments so there is

no need to explicitly assign a lambda to

a variable

so if i want to find the product of

let's say 15 comma 30

if i run it i have the result 4 t

let's change the arguments let's say i

want to find the product of 5 comma 7

the answer is 35

so this is known as an immediately

invoked function expression or iife

which is often pronounced as iffy

now you can also use keyword arguments

using lambda functions let me show you

what i mean

i will create my lambda function and

assign it to a variable called product

i'll say

lambda

let's say my arguments are x y and z

after that i'll give a colon and say

x multiplied by y multiplied by z

next i'll say print

my variable that is product

and here i am going to use keyword

arguments so i will say let's say

z equal to 5

x equal to 10

and y equal to 4.

you can see here

this need not be in an order as you have

defined the arguments

if i run this i have the result the

product of 5 multiplied by 10 multiplied

by 4 is 200.

now you can also

use default

arguments suppose i say add equal to

i'll use the lambda function

and say x comma

why i'm assigning a default

value of let's say 15 and z let's say

i'll assign a default value of 24

then i'll give my colon followed by the

expression that is x plus

y plus z

now i'll say print

add now here i'm going to only pass in

my value for x since i've already

given a default value for

argument y and z

so

my function only needs

one argument that is x so let's say i

want x to be

20.

if i run this

you see the result here so 20 plus 15

plus 24 is 59.

now you can also use the

asterix

args parameter or args

so this allows you to define as many

arguments as you want

so i'll say addition

equal to

lambda

then i'll say asterix ergs

so this will

allow us to pass in as many arguments as

you want

and i want to find these sum of

args so i'm using the inbuilt sum

function in python

now i'll say print

my variable name that is addition

and let's say i want to find the sum for

four

values or four arguments let's say 20 to

40 and let's say

50

if i run it so the value is 112 so 20

plus 2 plus 40 plus 50 is 112

cool now lambda functions are also used

with higher order functions which take

one or more functions as arguments

or return one or more functions let me

show you

so i will define a variable

called higher underscore

ord underscore f u n which stands for

function and y d stands for order

so i'll declare my lambda function

suppose the parameters are x

and then i have a

function

then followed by a colon i have

expression as x plus

function of x

now i'll say

higher underscore ord underscore

f u n

and i'll pass in my two

arguments let's say my x is 20

and for this

function

i'll have

a lambda function defined i'll say

lambda x

colon

x multiplied by x

now

let me just run this and i'll show you

the result okay so what it did was

it added

my value of x that is

20 with

function of x or f u n of x what is f u

n of x fun of x is

x multiplied by x so 20 multiplied by 20

is 400 so this becomes 400

plus x

which is 400 plus 20 hence the result is

420

so this is known as a higher order

function now let me show you another

example

let's say i want to display order event

by

taking the value of x

i'll say lambda x colon

here i am going to pass in my expression

if x

mod

2

will give a space here

i'll say and

odd

or

even

now i'll give my argument value let's

say 30

the result is even because 30 is

divisible by 2

i'll just change this to let's say 15.

if i run it the answer is odd because 15

is not divisible by 2

let's say i have 150 the answer is even

now moving ahead

so let's write a lambda function that

checks if a string is a substring of the

given string

so i'll create a variable called sub

underscore

string

now i'll assign this

variable with a lambda function i'll say

lambda

my

argument let's say string

i'll give the colon and pass in my

expression string in

let's say my string

has this message welcome to

python

functions

tutorial

okay

so we are going to check if a string

let's say in to welcome python java

anything whether it is present inside

the string which is welcome to python

functions tutorial

now let me go to the next line

i'm

going to print

sub underscore string

and let's say i want to check for my

string

let's say java

if i run it it gives me false because

the word java is not present inside my

string welcome to python functions

tutorial

suppose i write

python

now one thing to note here is

the p is small and here the p is in

capital letter

if i run it it again gives me false

because

python is case sensitive now if i make

this as capital p it will result in

true

let's say i want to say

instead of tutorial let's say i have

training

if i run it it tells me false because

the support training is not

there in the string welcome to python

functions tutorial

i'll change this to tutorial

you see here i have my result as true

all right

now let's see how to use lambda

functions using filter function so we

are going to filter a list of numbers

using a specific condition

so i'll create a

list called num

let's say it has values 40

10 40

then we have 56 27 let's say 33 15 and

70.

so this is my list

now i'm going to use

my lambda function

along with the filter function

so i will pass in my variable as greater

i'll say list

then i'm going to

pass in the filter function and inside

the filter function i'll use the lambda

function

and i'll have my

argument as num

and my expression let's say i want to

filter only those values

which are greater than 30

so i'll say num greater than 30 this is

my expression

or the condition that we want to check

i'll give a comma

and

i'll have my next argument as num

and let's go ahead and print the

variable greater

if i run this there you go you can see

here we have all the values from the

list or the numbers from the list that

are greater than 30 so we have

40 56 33 and 70. so

10

27 and 15 are

less than 30 and hence those three

values were not printed

now let's say you want to filter a list

of numbers that are divisible by four

so i'll create another list called list

one

and

let's say i'll have the

same

values in the list so i'll just copy it

and i'll paste it here

and i'll create my variable let's say

divide

i'll say divide equal to

list one

use the filter function

followed by

the lambda function

i'll say x

colon

then i'll have my expression

x

mod 4 should be equal to equal to 0

i'll give a comma and pass in my

next argument as my list 1.

now

i'm going to

say print

divide

okay

okay i'll remove the bracket here there

is no need of a bracket here cool

and we'll delete here as well

now let's run it

okay there is one error here this should

be list one

let's run it again

okay there is some error let's debug it

okay so this should be the function list

cool

there you go

so here you can see we have two numbers

40 and 56 that are divisible by 4.

the remaining

numbers are not divisible by 4 and hence

were not printed

all right

now let's go ahead and explore how you

can use the map function along with the

lambda function

so the map function accepts two

arguments a function and a list it takes

that function and applies it to every

element of the list and returns the

modified list

so we'll create a list called

list2

let's say equal to

and again we are going to have the

same values in the list as above

so i'll just

copy those values

or the numbers and i'll paste it here

okay

now

let's say

i want to find

the value of a number multiplied by 2 so

i'll say

let's say the variable name is double

the num or double the number

i'm going to use the list function

followed by the map function this time

and then we'll have our

lambda function

i'll pass in my argument as x

colon

followed by the expression

so x multiplied by 2

i'll give a comma and then we'll have

the list that is list 2

there's a spelling mistake here this

should be list 2 all right

now

i'm going to say print

double

underscore the

underscore num

make sure there is no space

in the

variable name

now if i run it

you can see here we have

multiplied every number in the list by 2

so

10 multiplied by 2 is 20

40 multiplied by 2 is 80. similarly 30

multiplied by 2 is 66

15 multiplied by 2 is 30 and again we

have

70 multiplied by 2 is 140

so this is how you can use

map function with

lambda functions

now suppose you want to find the power

of a number let's say i want to find the

power of a number raised to 3

so i'll create a list called list

3

let's say i have values 2 comma 5 comma

10 comma 6 comma 4 and then let's see we

have 12

i'll say

cube

so i want to find

the value of a number raised to the

power 3

so for that i am going to use the map

function followed by the

lambda function

i will pass in my argument x

and then

here i am going to use the inbuilt

power function in python so pow

my

argument x

and this x i want to raise it to the

power of 3

and then i'll have my

next argument which is

list underscore 3

or list 3

okay

now

let's

print the list so i'll say list of

cube

i'll run it

you can see here

so 2 raised to the power 3 or 2 cube is

8 5 cube is 125

10 cube is 1000

6 cube is 216 4 cube is 64 and 12 cube

is

1728.

now coming to the final section of the

demo where we'll see how to use

the reduced function in python along

with the lambda function and then we'll

use a lambda function within a user

defined function

so first let's look at how to use reduce

in python

so reduce applies a ruling calculation

to all items in a list you can use it to

calculate the total sum or to multiply

all the numbers together so reduce

function is a part of

func tools module so to use the

reduce function you need to import the

func tools module first so i'll say from

funk tools

import

my function that is

reduce

and then i'll say

let's say i have my list 4 this time

i'll create a list

i'm going to take the same values as

above

and i'll pass in within a list

and now

i want to find the sum of all the

numbers that are present inside this

list called list 4

so i'll do that using my reduce function

followed by the lambda function

so i'll say x

comma

and i'll give my expression as

y colon

x

plus

y

give a comma and pass in my last

argument which is my list itself which

is list four all right

and then i'll say print

sum

let's run it

there you go so 2 plus 5 plus 10 plus 6

plus 4 plus 12 is 39

so this is how you can use the

reduce function in python suppose you

wanted to find the

product of all the numbers present

inside the list so you can just

use the

asterisk instead of the addition

operator now if i run this

you have the product of all the numbers

that were present inside the list that

is list four we have twenty eight

thousand eight hundred

now

let me show you the final demo that is

using a lambda function in a user

defined function

so first of all i'll create a

user defined function to calculate the

value of a quadratic equation

so

for some of you who don't know the

formula quadratic equation it is

a x square plus b x plus c so we are

going to use that formula in our

function

and find the value using

lambda function

so i'll create a user defined function

called quadratic

and it will have

three arguments a comma b comma c

i'll say

return

and here in the return expression i am

going to pass in my lambda function i'll

say lambda

x which is my

argument i'll say x

colon

then i'll have my equation which is a

x square so i am saying a multiplied by

x

raised to the power 2 so i am using

double

astrix

plus

b

multiplied by x so this becomes ax

square plus bx

plus

i have my constant that is c

now

just go to the next line

i'm going to create a variable let's say

f

i'll have my

user defined function name quadratic

i'll pass in the values for a b and c

let's say a is 2 b is 3

and c is let's say 5

and i'll call a of 1

the value of x is 1

the value of a is 2

the value of b is 3 and the value of c

is 5

now let's run it and see the result

so

ax square plus bx plus c

for

equal to 2 b equal to 3 and c equal to

5 the result is 10.

now let's change it to let's say i want

the value of x as 2 if i run it

you have the

equation evaluated and the result is 19

all right

so let me first just give you a

brief of what are the

syntax for these functions what are the

signatures what are the input parameters

required and then we will jump into the

jupyter notebook and run some examples

so what is a map function the map

function takes another function as an

input and the second input is a sequence

of iterables it could be a list it could

be a set it could be an array or

anything you want and it returns the

output after executing the function

which you have passed as a parameter on

each of the element of that iterable so

the function could add the values could

multiply could divide or any

mathematical operation you want to do or

even you can perform certain string

operations which we will take a look in

the examples but the idea is that you

want to apply the function on each and

every iterable item individually so the

map function helps you achieve that

also in our examples we will take a look

that you don't need to explicitly define

a function you can also use lambda

functions which are inline functions uh

so you don't need to

increase the line of code you can reduce

the lines of code by just writing the

function in line and that way it will

make it more simple

[Music]

the next function which we are going to

talk about is the filter function

now what is the purpose

the purpose of the filter function is to

reduce the size of the iterables based

on the condition which you will pass to

the filter function

so syntactically it is very similar to

map function but the only difference is

that you need to pass a function which

carries a condition for example you have

a set of i tables one two three four

five six seven eight nine and you want

the function to return values which are

greater than phi

so

your filter function should have a

condition which says

that the i tables greater than 5 should

only be returned by this function

so that's why you have to make sure that

the filter function always have a

condition which is either true or false

so based on whatever condition matches

as true

the filter function will only return

those values as an output so we will

take a look

and the same

concept applies either you can make a

explicit function or you can apply

lambda function inline

the third function

which we are going to talk about is the

reduce function

the only difference between reduce

function and the other functions which

we talked about

the map and filter is that reduce

function always returns a single value

so it combines all the

values in the iterable your list your

array your set and returns a single

value so you can apply the mathematical

functions like for example you want to

add all the values in your write table

or you want to multiply so it will

multiply sequentially and give you the

output

and the same

concept applies over here you can have

lambda functions or explicit functions

also with one thing which you need to

remember is that you need to use

function tools module

to to import the reduce function

so we will take a look at that while we

will be running certain examples

okay

so here we have so we will start by

running our examples so first we will

start with map

so let's start by

defining a very simple function

which adds

two values

right and returns you the added value

right

so in the next step

we will define a

list of iterables so here we have taken

an iterable list of

four items four six eight nine numbers

now

in this step we will apply the map

function now

please notice that we are sending two

parameters to this map function one is

the

function name which is add and the

list which is numbers

okay

now i'll print

the out

but it's an object so right it's not in

a readable format so i need to convert

the out object back to a list

and now i'll be able to print

and here is my expected output so i had

four numbers in my list which is four

six eight time and the map function have

has added the numbers to itself four

plus four six plus six eight plus eight

nine plus nine and so that's how you're

getting the output as expected

[Music]

now let's take a look at another example

we're going to redefine our list

and we are going to use now a lambda

function

instead of an explicit function which is

going to multiply

the numbers in my list

within with themselves

and

we're gonna

uh print my out object

convert it back to a list

and then i'll print

converted list object

and here you go this is my output 4

multiplied by 4 6 multiplied by 6 8

multiplied by 8 and 9 multiplied by 9.

okay

so here in this example we have seen

about lambda function

now

we have been up performing mathematical

operation as i mentioned earlier we can

also perform certain string operations

so let's take an example

what i'm doing in this example is i'm

creating a map and i'm just converting

all my lowercase strings to uppercase

and i'm just printing my list now

after conversion

so such kind of uh you know

string operations are also possible

let's take another example where we are

going to print the length

of each of the

string which is there in my list

and i'm using lambda function

and here it is

so now you can see the list

the length of each and every string

variable is 3 5 6 and seven

okay

so now these were the examples of map

object

map function now we will

talk about

filter

so let's start with a simple example so

as i mentioned the filter function

should help always have a condition

so let's create a

function which has a condition saying if

a is greater than 5 then return a

it means that you need

to only return numbers which are greater

than 5 in my list

so now i'm going to call this in my

filter function

so if you see the syntax here please

notice filter you pass the fill and the

list

and then you print the out object after

converting into the list

and only the numbers which are greater

than 5 are printed

now let's take a look at

a lambda function example rather than an

explicit function

the same example but now instead i am

using a lambda function

and i am going to print it

output should be the same

okay

so the

the only change is in the syntax of the

function definition here we have

explicit function and here we have a

lambda function output is the same

now let's take an example of

a string operation string filter what

kind of string filtering we can do

so

i have an example over here

so what i'm going to do is i'm going to

have a list of string arrays

which is going to return me only those

strings which have e in them occurrence

of e

okay

so i've created a function veggies with

e

and within this list of veggies peas

garlic ginger beetroot carrot i will

only get those string variable values

which have e in it

okay so i've got the result p is ginger

and beetroot

right and garlic and carrot have been

discarded

now let's run this similar example with

lambda function

where i'm saying that okay give me those

vegetables which have r in it

so i'm just gonna run this

and print my

map

[Music]

okay and here is my expected output

garlic ginger beet root and carrot

so what have we noticed is that similar

to map filter function of course the

only difference is the function should

have a condition

which should return a true or false and

based on that the iterable list get

filters out

now

let's talk about

reduce

now as i mentioned

the first important thing is that

we

import the reduce function from function

tools okay

and then

we apply a

lambda function so we're going to start

off with just taking an example of

lambda

so here is my list of four elements 10

35 50 and 20 and i'm adding

the numbers in this list okay so so the

map function is not gonna the reduce

function is not going to add the numbers

to itself but to the subsequent number

in the list right

so what is the expected output right

expected output is 10

plus 35 45

plus 50 95 plus 20 115 so

what the reduce function has done is it

has added the numbers in the list

amongst themselves right in the orderly

fashion

now let's take another example instead

of addition we'll do a multiplication

okay

so here what we have done is we have

multiplied 9 by into 7 into 23 into 4

and we've got this answer

so this is another way of doing it

now instead of lambda function i'm just

going to show you a simple

um

adding the numbers

and define a function where you add the

first and second number

and then

you pass the function name

to reduce so custom sum and the list

similar to what we had done for map and

filter

and now you can print the result

now one thing to notice is that this

result is a single number you don't need

to convert it back to a list so you

don't need to do that transformation you

just

simply print the result

and here it is 68 3 plus 4 plus 6

plus 9 plus 34 plus 12.

so what is the class in python

a class is a virtual entity or a

blueprint for creating objects

a class in python provides a means of

bundling data and functionality together

you can think of a class

as a school so here school becomes your

class a school has attributes about the

students classrooms labs playgrounds etc

hence the school can be called a class

and classrooms labs desks playground

assembly are the attributes or objects

of a class

a class comes into existence when it is

instantiated or initiated

we can create as many objects as

possible in a class now in python a

class is created using the keyword

called class

followed by the class name the first

string inside the class is called

docstring and has a brief description of

the class

below you can see the syntax of creating

a class in python we have the class

keyword followed by the class name this

should be a valid python name and then

you have a colon

below that you have the statements that

should be present inside the class

now let's look at an example of a class

in python

so here you can see we have created a

class called student

and we have two variables the student id

and the name of the student

and after that we have created a

function using the def keyword so this

is a user defined function and the name

of the function is called display

and inside

the display function we are

giving a parameter called self so here

the self parameter refers to the

current class object and accesses the

class variables we can use anything

instead of self

but

it must be the first parameter of any

function which belongs to the class

now moving ahead

so let's look at what is an object in

python

so an object is also called an instance

of a class and the process of creating

this object is called instantiation

now you need to create an object of the

class if you want to use the class

attributes in another class or method

now the procedure to create an object is

similar to a function call so

below you can see we have created a

object called stu and we have called the

class student using parenthesis so this

is how you create a class and after that

we are displaying

the message to be printed by calling the

class name followed by the function

which is present inside the class

so this example will create a new object

instance named stu

we can access the attributes of the

objects using the object name prefix

now moving ahead

let's understand the initialization or

init method in a python class

the init method is similar to

constructors in c plus and java

all classes in python have an init

function it is always executed when the

class has been initiated you can use the

init function to assign values to object

properties or other operations that are

necessary to do when the object has been

created

so the init function is called

automatically every time the class has

been used to create a new object

so here you can see we have used

the init method we have

defined using the def keyword then we

have parameter self name and age

so we are calling

the

class using this object called s1 and

then we have passed in the values for

neiman age that is delay and his age is

27 years and after that we are printing

the age and the name as well

all right now let's get started with our

demo on

classes and objects in python on the

jupyter notebook

so i am on my jupyter notebook let me

first go ahead and

rename my notebook to classes and

objects in python

all right i'll click on rename

first of all

let me show you how to create a simple

class

so i'm creating a new class

using the class keyword so this is

the keyword class and

followed by the keyword i have my class

name called new class

one thing to note here is the

class name should always be a valid

python name

i'll give a colon and in the next line

i'll just say

x equal to 50

so this x is a variable which is present

inside my

class called new class now if i run it

i have my new class created now if you

want to display the

value of x you can just say new class

dot x now if i run this you can see here

i have my value printed which is 50.

now

we'll see another simple example to

create a class and to call that class

using

an object

so i'll say class

then i'll say

new class let's say 1

give a colon

and i'll create a variable called x

equal to 100 so my x is a variable which

is present inside new class 1 and holds

a value 100

now i'll give a comment

create object

so to create object i'll

define a variable called r let's say r

stands for result and then

i'll say

new class 1 so i'm calling my class

and then i'll say print

r which is my new object dot

x

let's run it you see here i have my

value printed of x which is 100 so this

is how you can

create or initiate a class using an

object

now let's see how you can use the self

parameter in a class

so i'll go ahead and create a class

called

student

give a colon

then i'll have some variables

or the

attributes of a student let's say the

student id is 10 and the name is

anderson

now

inside the class i'm going to

create a user defined function called

display

so i've used my df keyword followed by

the

function name that is display and inside

the display function i'll use self as my

parameter

and then i'm going to say

print

self dot id i'll give a comma

and i'm going to print

my name so i've written self dot name

so i'll run this

and then

we're going to create an object called s

and we'll call our class

that is student and i'll say s dot

display

now let's run it and see the result you

can see it here

we have called the

class using this object called s so it's

displaying

the id that is 10 and the name that is

anderson

cool

now we are going to see an example where

we'll pass a dog string so in the slide

we discussed that the first

string inside the class is called a dog

string and has a brief description of

the class

so let me show you an example how to

pass in a doc string

i'll create a class again let's say

called student

give a colon

and then we'll have our message

which is essentially a doc string i'll

say this is a

student class

then i'll create a variable called age

let's say the student's age is 14

and then

i'll create a user defined function

called welcome

and

have my self

parameter

after that i'll say print

my message let's say hi

comma

welcome to

section

let's say b

and then

i'll come out of the class and we are

going to

print

class name that is student i'll say

student dot age

and then i'll say print i'll just scroll

down

student dot

then i'm going to use the

function name that is welcome

and after that

to print the

docstring message i'm going to say

my class name that is student

dot i'm going to use underscore

underscore doc underscore underscore

now we have created a class called

student that has a variable called age

so we are going to display the age of

the student and then

we are going to display the

dot string so here we are not going to

print the message which is present

inside the function called welcome

let's run it

you can see it here

we

have the message printed so first we are

printing the age of the student and then

we have the doctrine message that is

this is a student class

all right

now let's move ahead we are going to see

how to use the

init function

in a class

so i'll say my comment init function

all right

i'll scroll down

i'll create another

class called student

this time we are going to use the init

function so i am writing def

space

underscore underscore init

underscore underscore

then we'll have our self parameter let's

say the next parameter is

name

and then we have the date of birth of

the

student

i'll say self

dot

name equal to

name

then i'll say

self dot

dob or d to birth equal to

a parameter that is

dob

and then

i'll say

my object let's say s1

i'm going to call my class student

and it will have

values of name and date of birth let's

say the name of the student is harry

and

the date of birth let's say it is

29

october

1992

all right

finally we are going to print

s1 dot name

and then i'll say print

s1 dot

date of birth

let's run it

you can see it here we have the name and

the date of birth of the student printed

cool

now you can also modify the objects that

you have created suppose i want to

change the

name from harry to virat because my

object was s1 dot name

harry i want to change this to virat let

me show you how to do it

this is very simple i'll just give a

comment that is modify objects

the way to do is you just

see the object name that is s1 followed

by the parameter that is name

equal to

let's say virat

now if i print

s1 dot name

i'll have virat instead of

harry

okay

now

if you want to delete the object

properties let's say i want to delete

one of the properties let's say i want

to delete name property of the student

to do that

i can use the del keyword followed by

the object name that is s1 and say s1

dot name

now if i print

s1 dot name it will throw an error

saying student object has no attribute

name because we are first deleting it

and then we are trying to print it and

hence

python cannot recognize this attribute

name

now you can also

delete objects that is all the objects

using the dl keyword

so this means we can delete both the

objects that we created above which is

name and date of birth

so the way to do is i'll just say dl s1

so it will delete all the objects

that is s1 in this case

i'll run this

and then let's say i want to print

s1 dot

date of birth

you see it here

python says name s1 is not defined

because we deleted it

cool

now coming to the final section of the

demo we're going to create a simple

class with init method again

so this time my class name is let's say

animal

give a colon and then i'll write my

init method using the

df keyword

i'll say self comma

name that is the name of the animal as

the parameter

i'll say self dot name equal to name

and then

i'm going to create another function

called tef

which is essentially a welcome or agreed

message

and that has a parameter that itself

i'm going to print the greet message or

the greeting

i'll say hi

my name is

give a comma and then say self dot name

now i'm going to create

my object a1 to

[Music]

initiate my class

so i'll say animal which is the class

name let's say the name of the animal is

puppy

then i'm going to say even dot

greet

i'll use parenthesis let's run it

there you go

you see here we have a message printed

hi my name is

then

using the self dot name

argument of the parameter we are passing

in the value that is poppy all right so

that was a demo session on

python classes and objects so we saw how

to create a simple class in python and

then we saw how to create

objects to

call a class

and then

we

saw how to use the self parameter

after that we saw

how to

print a message that is present in the

docstring of a class

and then we

checked a few examples on using the init

method in a class then we learned how to

modify

objects and delete objects in a class

and finally we saw another example

on init method

all right

we are going to talk about the concept

of inheritance

the types of inheritance which are

applicable so the different kind of

inheritance which we are going to talk

about are single level inheritance

multi-level hierarchical and multiple

inheritance and we are going to support

each concept with an example

before

we begin this session i just want to

highlight that inheritance is not a new

concept in any of the programming

languages

just like in python this concept is

applicable across multiple programming

languages like java c

etc

now what is inheritance inheritance

provides the reusability of a code

it allows you to inherit what you have

written in a particular class or a piece

of code and you don't need to rewrite it

you can inherit it

so that is the main purpose of

inheritance it is creating a new class

that utilizes the properties

and behavior of an existing class

so we will support this with an example

so if you take a look at the syntax the

sample syntax over here you have a base

class and you have certain attributes

functions

uh associated with the base class and

then you have a derived class in which

you extend basically you inherit the

base class and you inherit the

properties of the base class

now the new class formed is called the

derived class or the child class you can

call it anything derived child or

subclass and the existing class whose

properties are inherited is known as the

base class parent or super class these

are synonymous so any

where you hear that okay you know you're

working on a child class or derived

class you can

easily figure out that you're talking

about a derived class and whenever there

is a

reference to a parent or a super class

it means we're talking about the base

class

right

now

with this

concept with this idea let's move ahead

and

look at the different types of

inheritance which are possible in python

now here we are trying to

display pictographically

diagrammatically the different kinds of

inheritance and this will make

understanding more clear

now let's talk about first single level

inheritance you have a class a and you

have a class b so basically only till

class b only single level child is

inheriting the

attributes the properties of classes so

that is what we call as single level

inheritance

multi-level is you have

multiple level of inheritance

in for example class b here inherits

class a properties and class c inherits

class b properties so ultimately you can

see

that the the properties gets trickled

down till class c right so that is the

example of a multi-level

right

next is hierarchical in which

two classes are inheriting from a single

class class b

is also inediting from class a and class

c is also inheriting from class a so

both class b and class c

are kind of siblings to the parent class

a right

multiple inheritance it means that a

child class in is inheriting properties

from two parent classes

so in this example the class c is

inherited the properties of class a also

and class b also

so we will be looking at these examples

when we will be running in python

now let's

take this example with a real world

object right let's first try to

give you a

view of how

we are going what we want to explain in

the inheritance with real world objects

right now here we are taking an example

of a black and white tv and a color tv

now single level inheritance in this

type of inheritance there is only one

single derived class from a single base

class as i mentioned earlier so for

example you can assume there is a class

called black and white tv and what are

the attributes of a simple black and

white tb it has a regulator it has a

sound adjustment

now

there is a child class called color tv

which inherits the basic attributes of

course a color tv also has a regulator

or sound adjustments but

additionally on top of it it also

provides new features like color picture

and cable connection so now

what do you understand by this is that

the child inherits the basic properties

from the print class

but it also adds on the new additional

features so the color tv does not need

to rewrite

or

the

functionality of a regulator and the

sound adjustment it has inherited

multi-level

very similar to single level but now we

are adding more features

so like in the previous example color tv

inherited the features of black from

black and white tv

now we move a step ahead now there is

another classification another

advancement of wi-fi led tv so that has

also narrated the features from color tv

right so it's a multi-level inheritance

so just to reiterate the black and white

tv had channel regulator dish antenna

the color tv added additional features

of color picture quality and cable

connection

and the wi-fi enabled tv added the new

smart features to the tv which it

inherited from the color tv

multiple inheritance now in multiple

inheritance the derived class is

inherited from more than one base class

right so now for example over here you

have a class called android which is an

android operating system based class

and one is the wi-fi led class which has

the wi-fi features of like sound picture

wi-fi enablement and if you combine all

these features and bring it into another

child class that class is the smart tv

class which has the features of android

and the features of wi-fi led tv and

then you call it as a smart tv it has

all the android applications it has the

wi-fi features and etc so this is the

example of multiple inheritance getting

the best of

all the parents

here kill

if more than one class is inherited from

the base class right so now if we just

tweak our prior example and you know

just

rephrase it what we are saying is now

from the black and white tv you can also

make a color tv you can also make a

smart tv or you can also make a wi-fi

led tv right so there is no restriction

as such so basically the color tv is

also inheriting the features of a black

and white tv smart tv is also inheriting

the features

of a black and white tv and the wi-fi

led tv also is narrating the features

from black and white tv so it's a very

typical example of a hierarchical in

inheritance

so now let's

quickly look at the examples

okay so let's start off

with a

very simple

single

level inheritance

let's make a class

and

create a function

called speak

and print something

okay

now let's make another class

so what we did was we created a class

called homo sapiens and in the and now

we are creating a clause called man

which inherits

uh the attributes

of homo sapiens

and we say

create a function which is specific

to man so homo sapiens has a function

which called speak and man has a

function called talk

and let's print it

now

let's create an object of

man

now what does this signify

the man

class is also inheriting whatever is

there in homo sapiens so man can even

talk and he can even speak right

so what we are going to do is

first we are going to execute the

function

speak

so the

the base class function got called speak

and it is printing homo sapiens speaking

and also we can call the child function

man talking okay so so if you see

this is the basic difference which we

want to highlight

that

just you have created the object only

for the child class not the parent so

now making by making the object of the

child class

you can invoke the parent class function

as well as the child because the child

has inherited the parent features

now

let's take an example of

multi-level

so we will

continue from our previous example we

will create class homo sapiens

define in

functions peak

and

print

now we will make another class

man

now we are saying

man can

walk

so we are saying man walking

now this is the third level this is the

multi-level

man child

and

we are saying that a man child can eat

so ultimately the man child can speak

can walk can eat all three operations

can be performed

so we are gonna make a object of

man-child

and now

python will allow us

invoke

walk function

speak function

and

eat function

so this is a typical example of

multi-level

hierarchy

now

moving to our

next

type of inheritance which is the

multiple inheritance

where

the child

is deriving

attributes properties from

two parents

so we will now create a class called

calculation1

in our example

and let's make a function

sum

and

it will return

calculation x plus y

second

calculation two

and

let's create

operation subtraction

and it will return x minus y

okay

now

we will create

the derived class which is inheriting

both calculation one and calculation two

and

let's create its own

function called

multiplication

okay so derived class now has a sum

function subtraction function and

multiplication okay

so let's create an object for derived

and

now let's

invoke the relevant functions

so sum

120

subtraction

it should say minus 40

and

multiplication

so if you see

it's it's different from multi-level

it's multiple it means that the child

class

has inherited from two parents it's

relevant functions right

and that's how we are able to call them

in the derived class

now let's take another type hierarchical

inheritance

okay

so in hierarchy

inheritance

let's go back to our example of

first we have the black and white tv and

we will create a function called

antenna

print channels are telecasted through

antenna

then we will create

color tv

and

we will define its own function called

cable connection plus it has an edited

the function called antenna from black

and white tv

here it is okay

now we are going to create another

class called as

wi-fi led tv which is also in editing

from black and white

now in this we are defining bluetooth

tethering function

[Applause]

okay

and let's make another smart tv

okay and then we are gonna

you can watch

android applications on otp platform

right so this is the

class of smart tv

okay so what we have done eventually

over here is we have created a black and

white tv

color tv also inherits from black and

white tv wi-fi led also in edits from

black and white tv smart tv also edits

from black and white tv

okay now

let's try to

create the

relevant objects

we will first create an object of color

tv

then we will create

wi-fi led tv

and then we will create

smart tv

okay

now we will have the relevant functions

available to invoke

so both all the child all the children

objects now will have an antenna

function a1

a2

and a3

all three are having the antenna

function so we can just try to print it

okay

and then

we can invoke the relevant

child functions

a1

cable connection

bluetooth triggering

and

android applications

so if you see this is an example of

hierarchy

you have color wi-fi led in smart tv all

inheriting the black and white tv

features

and its own

its own feature

[Music]

okay

now along with this concept let me just

also introduce

some relevant concepts which are

applicable

along with

the inheritance concept which will be

helpful

i also want to show you

the example of

init function init function

is a constructor in python language

and it is called by default whenever you

instantiate an object

so let me give you an example over here

so here you have a

class person

and you have

we are just defining the init function

the constructor

okay and

we are just

defining certain attributes

instantiating certain attributes in the

person first name and the last name

and another function which i am calling

is the

print name

and i'll print the name it's a

straightforward function

okay so what i'm doing is i am creating

a child class now

called as student

which is inherited

uh the features attributes of the person

base class

and

i'm also making a constructor for

student

and from student i am invoking the

constructor of the person class right

so now if you see i'm going to make an

object of student

and initialize it with

the self the first name and the last

name

and in eventually

the

parent class init function is being

called first name and the last name and

this function diff print name it will

print james anderson right as i have

already initiated the

parameters

okay so if you see now what have i done

i have

the attribute values in the parent class

are getting printed

by invoking the constructor of the child

class

so what happened when you invoke student

by default this init function got

invoked the parameters of james and

anderson got passed then from person you

invoke the constructor in it and here

now the first name and last name got

initialized

and then it got printed

so this is the basic feature of a init

function

now

like the way i have called person dot

init over here i i can also make a call

to super there is a keyword called super

keyword

so let's just take an example of super

keyword

okay

let me have my child class like the

previous one parent class the person

class

and

i'll have to just make a change in my

student class

in the init function instead of parent

dot init i will call

super dot in it

this is the keyword

super function

which will always

invoke the parent class

gives you the handle to the parent class

and then you can invoke the relevant

method

and

the invocation methodology will be the

same

and you can

check the output it's going to be the

same but it's that the syntax is

different there is another keyword which

is available for you to invoke the

parent so you don't need to know the

class

of the parent you can just make a call

to the super

now let's also take a look at another

utility utility function called is

subclass right

so

what we are going to do is

we are going to create a function

calculation one

calculation two okay so we have created

two classes calculation one calculation

two independent classes no one

inheriting each other

now we are going to create a derived

class

now this is the example what we had done

earlier very similar to multiple

inheritance so we are just actually

creating a

multiple inheritance

example

okay so you have a derived class which

has multiple inheritance from

calculation 1 and calculation 2

summation multiplication and divide

relevant functions are there

now we will check

which class is a sub class of which one

right

so let's create an object of derived

now what we want to print is that

whether derived

is a sub class of calculation 2

and it should return true

and let's see

another is calculation 1 a sub class of

calculation 2 it should return false

right because these two are independent

classes so is subclass is another

function which is available in python

which helps you

decide you know you can check whether

which is a derived class and which is

not a derived class

next

let's take an example of another

function called is instance okay

will take the same

set of functions

create an object of derived

and check

whether

the object d is of which

is it is it of a

instance of class derived or not it's

true so instead of derived if i make it

as calculation 2 for example now if i

say c

equal to

calculation 1

and say c

is instance of derived

it should say false but if i say

calculation 1

it should say true

and if i say

calculation 2

should say false because

calculation class is an independent

class d is a derived class from

calculation one and calculation two so

basically d is in is instance of both

calculation one calculation two so it

will always return true

we are going to talk about what is a

python nitrater what are iterables right

what are the iterable objects

how an iterator works

and then we will also discuss about how

to throw a stop iteration exception

basically when you reach the end of a

list

then you can throw a stop iteration

exception and we will see that with an

example

now what is a python iterator

python nitrator is an object that can

traverse through iterable objects in

python like lists tuples dictionaries

sets

and returns data one element at a time

so basically you can traverse through

these layers one at a time and then you

can use it as per your custom

requirement but iterator as an object is

available to you is a tool available to

you in order to traverse through each

and every element

now

they are implemented within for loops

comprehensions generators in python

implicitly they are not visible up front

but they are hidden in plain sight so

basically when you're using loops when

you're using generators comprehensions

implicitly python is actually converting

them in the back end in an iterator

object and giving you the results

now what are iterables on which you can

iterate

lists tuples dictionaries sets as i

mentioned are all iterables or iterable

objects other than these you can't

perform any iteration if you have not

created an object of list tuple or

dictionary or said then of course your

right variable will not be of any use

and

these objects internally possess an item

method iter method which is used to get

an iterator a handle to an iterator and

then you can start looping it or you can

start accessing the elements of the

iterator

now how iterator works

python iterator implements internally

these two methods which you are seeing

on the screen underscore underscore item

underscore underscore brackets and

underscore underscore next underscore

underscore bracket

now these two methods are implicitly

implemented by python for any internal

implicit iterator

object

but if you have to write your own custom

iterator

then you need to override these methods

and i'll show you in my examples in

jupiter notebook

the iterator object is initialized using

the either method so basically whenever

you have to create an iterator object

you need to initialize it with iter and

then use next method in order to

traverse through it

now stop iteration exception so as i

mentioned when we reach the end of an

iterable right like suppose you have a

list or a set which has a length of four

when you have ended the fourth element

and you're trying to access something

beyond fourth element which is fifth

then of course you can implicitly raise

a stop titration exception or python

will throw it so we will see that with

an example but you will get a stop

iteration exception

now so to prevent in order to uh handle

it

or

manage it in your course we use top

iteration statement to raise an error

you can raise your customer error so you

can catch this exception

and then raise your custom error in the

underscore underscore next method

so now let's uh support everything with

our examples

let's start with a very basic

example of an iterator now let me create

a list

with just four

numbers

and

as i said i'm gonna initialize my

iterator with item method so now i have

created a list and now i am initializing

it with item okay

now using next i'm gonna print my first

element four okay so it means the iter

internally has given me handle to the

first element

and now as many times i move print next

i am moving to the next element

so now i'm also going to show you a

different syntax this is a syntax but

the output will be same it's a different

syntax to invoke underscore next so it's

output is going to be same but the

syntax is only the difference over here

so you're going to get access to the

next element

and then

my fourth element just 33 now i have

traversed through all my four elements

now what will happen if i again do next

i have ended i am at the end of my list

so i will get an exception of stop ice

iteration right and this is thrown by

python

now let's take another interesting

example if i want to perform iteration

on

strings

so i have created a variable and i have

initialized it with geeks

and now i have created an iterator on

top of this uh

string variable and i'm going to

traverse it

till the time i end reach the end of my

string

so let me

hydrate it and i'm going to iterate till

the time i get the stop iteration

exception

so also i might explaining here how to

cleanly handle the exception

accept

and then break if i get the exception

i'll break out of this program

and here you get the result

all the letters of my string geeks has

been printed individually

and i think it's a very important

example interesting example that how a

string has been converted now

point to be noted over here is

that python has internally invoked

underscore underscore iter and

underscore underscore next methods which

it has implicitly implemented for string

iterators so you don't need to do

anything

now let's take another example to how to

traverse through a list

using for

loop

so i'm going to leave for object in list

and just print the list this is without

a nitrater i'm just printing my list so

i'm just trying to show the difference

that if you use a nitrater or you do not

but how you can access the

elements in the list

now let's take an example

of how i can write my own custom

iterator

okay so i'm

creating a class where i'm overriding

the init method

basically initializing in is a

initialization

of my class where i'm gonna initialize a

variable max with zero

and then

i am overriding this is the most

important point over here i am

overriding i t e r method

and then

i am writing another overriding the

underscore underscore next method

where i am adding

6 to my number and then

incrementing my loop

so that

i

can move further

so in this underscore next method i am

just

moving beyond adding 6 and till the time

i reach the max variable so when i'll

invoke my class

i am passing 9 so it means that i should

not

go beyond

10 basically i should start my iteration

from 6 and will not go beyond 10 9 plus

1

so i should get numbers which are

between 6 to 10 as per my expectation

now before we diagnose the output most

important point is that how you have

converted your class to an iterator over

here

you in order to invoke make an a class

in nitrater it is mandatory you override

it ar and next method which you have

done over here

so now let's print

okay

so six so my

number started with 0 initialized with 0

and i added

six to eight so my first result is six

and now if i keep printing i will get

one value incremented

seven

eight

nine

and

ten right so this is the expected output

right

now

another example on the same lines i'm

gonna print the first 20 numbers using

my iterator

so i am

going to overwrite the iter method and

underscore underscore next method my

numbers now in this

underscore underscore next method i'm

just incrementing my number y one

not by six and i'm gonna stop at the

limit 20

so like i showed in my previous example

i'm gonna initialize first my class

and then

uh initialize my iterator and just then

gonna run a for loop on it

and here is the response output i have

printed the first 20 numbers because i

have created this limit

so i am initializing with one

and going till the max 20 number

but the point is it's not the output

which is more important over here the

most important concept over here is that

you have created your own iterator and

leveraged it we will talk about what is

a generator in python we will talk about

the advantages of using generators

and the utility of the next function

which

allows us to

operate with generators and print the

values within the generator so we will

see these

all these concepts with an example

now what is a generator in python

python generators lets you create your

own iterator functions that return the

traversal object with a sequence of

values

so basically even with iterators you can

only work on list tuples or sets but

with generators you can convert your

functions into iterator functions itself

and we will see that when we will be

working on a jupiter notebook

now another important feature in a

generator function is that a yield

statement is used rather than a return

statement

so basically

the return statement terminates a

function entirely if you use it within

the function and you know basically

return from the statement while the

yield statement pauses the function

there it is

and holding all its states all its

variables the values in the variables

and then continue

thereafter on the successive calls

so basically in a generator function you

use yield functions and i will talk

about the utility of this yield

statement within the generator function

how it helps in generating pipeline

but just to hold a thought over here and

understand the concept the yield

statement basically holds

the processing of the function at that

point and if you make an invocation of

that generator function again it starts

from there itself where you left it

as compared to return statement return

is a general exit

if you make an invocation of the return

statement from a function it will

restart again from the beginning if you

invoke it the next time and that's the

basic difference

so what are the advantages of using

generators it's very easy to implement

the code syntactically it's very simple

within the few line of codes you are

able to achieve

the

you know functions and able to implement

the logic

you can generate infinite sequence you

don't need to provide the range values

the starting and ending you can generate

an infinite value and i'll show you that

with an example

and

generators are very memory efficient

they are the most memory efficient ways

of processing huge data sets

they process the data incrementally and

do not allocate memory to all the

results at the same time they do that

incrementally

they really come in handy when

implementing data science pipelines for

huge data sets in a resource constraint

environment where you have

you know constraint on the ram and the

other resources of the hardware

now another biggest advantage is

pipelining with generators

generator pipelines are a great way to

break apart complex processing into

smaller pieces when processing list of

items so basically you can

break your complex code into smaller

pieces and then

invoke them as a generator

recursively and we will see that how

but basically you are making the complex

code look simple and making it invoke in

a pipeline fashion

now the another most important function

in order to deal and operate with the

generator is the next function

the next function is used to retrieve

elements from a generator object and

then print it so that's how you

basically

interact with your generate function

you cannot do that until unless you

don't use next function

so now let's quickly

jump to our examples

which we are going to support for each

of these concepts now let's start by

basically

creating our

first

generator function

i am going to

create a variable n initialize it with

one

and i'm gonna do a print

this is just for my

logging

and showing on the console that where we

have reached

and then i'm gonna say yield n

okay

so now here we are not exiting the a

function we are just

saying

that just uh you know this is the point

if you invoke the function again the

function will start from this point on

now here

you will

increment

and again if this is the second

checkpoint in the code

and similarly

this is the we're gonna have a last

checkpoint in the code

now in order to

create my generator now this is the

my generator initialization my gel

now if i

use the next function and invoke my

generator

now

my

generator has

been executed till this point right

n equal to 1

now if i

make a second invocation

now it has moved ahead and printed the

second so it is behaving like a loop it

is now behaving like a loop it is

behaving like a nitrater uh but i have

not created any list i have not created

any tuple but i am basically traversing

through the variables through the

sequence of the variables within my

generator

and if i again

print it

this is my last this is printed at the

last so all the

checkpoints within my generator have

been executed

now

the same example which i have over here

let me

call it in a loop

okay

so what i'm gonna do is i'm gonna

remove these invocations and just

replace it

with a loop call right so this generator

functions remain as is

now instead of writing my next

function

three times

i am going to just invoke my generator

in the for loop and this will get

invoked the number of times i have yield

in my generator

and my output should be

the you know these logs which i have

created

and of course the variables

yeah so see now what has happened is

now the output is all these three print

commands have been executed plus the

variable values of n has been imprinted

at each at point 1

2 and 3.

so when i initialize my item variable

during the for loop this item consists

of the variable values which are there

in my generator

now i'm going to show you

example of if i use a return statement

in my generator

so i am going to create another

generator

and

provide a value

now in during this in middle of this

generator i am just invoking return

and then i am

printing my second checkpoint

and then the

last checkpoint

now

i'm gonna initialize my generator

now if i invoke

my

first element of the generator i'll get

it there's no problem because i printed

the first item i called the value of my

yield and then i return

but now if i invoke my second element in

the generator

but before invoking second i have

already given the return statement

my

generator will exit

and i'll get the stop iteration error

now this is a python generated

exception which is denoting that you

have you cannot move beyond the first

item because you have returned from the

generator over here

so that's the difference if you just

remove this comment this out

and then run it

you will get your second item so it's

not the code exits if you write return

over here so i hope you are able to

understand the difference

now let's take another example now here

we are going to create a list and how

a implicit list like the way legacy way

we have been creating in python

differentiates like the way we are

creating a generator

so what i am doing is i am creating a

list with random numbers

and then another list in which i am just

square rooting

the numbers in that list

and similarly i am also creating a

generator

which

i am expecting the same output in the

new list as the generator

but i am going to show you different

ways

of traversing the generator as compared

to a list

now if you see this list underscore if i

just make a print call to this list

it's going to straightforwardly

uh square root

uh the numbers and give me the output

four nine sixty four and hundred

but if i print the generator

i will not get the expected output what

i'm expecting i will just get the

generator object which is not what i

desire so basically you can't just print

the generator like the list

you have to

either use the next or you have to use

the for loop which i had shown earlier

and print each and every item within the

generator

now this is the output which i was

expecting i was expecting the

line by line

output of each and every element in my

generator

4 9 64 100

okay

now this for loop is taking care that it

is not exceeding

the number of items the length of the

items in the generator so this is

automatically taken care by this syntax

but if you don't take care of it then

you will get an exception let me show

you another example

if i create a list

and now i'm creating a generator

which is square

of square of all my elements

so now one by one

instead of the loop i'm one by one

printing the output

second output

third element output

fourth element output

okay i have four now if i try to again

print

i'm exceeding the

length of

the

list i'm going to get an exception stop

iteration exception because i'm

exceeding the length right either i use

the 4

or if i'm using individual print and

next function then i have to take care

that okay how many elements are there in

the list and i cannot exceed beyond that

else the python will

raise an exception

okay

now i'll show another example of

highlighting the difference between next

and

the for loop printing i'm gonna create a

uh generator for 2 to the power n

so i'm initializing n with 0

and then just

raising it

2 to the power n

now here i'm initializing my generator

and printing it

and i am getting the expected output as

2 raised to the power 0 1 okay

now another way of doing this job is

i

loop over this

and i get the same output so if you see

it's only

i do not have only one element so either

you use for loop or you print using next

the output is going to be

same

now another important concept which i

talked about

if you want to print infinite infinite

numbers

so

or you want to do some infinite

calculations

i'm going to use print in

all

even numbers

so i'm gonna

write an

generator

which is gonna print

infinite number of even numbers

so i've created a generator

and now i'm going to invoke this

and mind you i have to kill this job

because it's going to keep running

it's going to keep running keep running

because it's constantly generating the

numbers even number

so i would have to stop this

but if you see

otherwise this is not possible in any

for loop the basic for loop you have to

give a range start and end of the length

but using a generator you can do

infinite

looping

right because here i have to kill this

job i have to do a keyboard interrupt

now i'm going to show you an example of

how you can use generators for creating

a pipeline

so i'm going to take example of

fibonacci series

create an example of fibonacci two

variables initialized with zero and one

and now

i'm going to

write the logic of fibonacci adding the

two numbers

to itself

subsequently and i'm gonna add yield

now this is my generator this is my one

generator

and i'm gonna create second generator of

square

so i'm gonna

show you in excel

what logic i'm going to apply and what

will be my expected output

so i am now squaring the numbers which

i'll get out as an output of

fibonacci

okay

now

i'm gonna

i'm creating a pipeline

like this

first i'm gonna generate fibonacci

series for the first 10 numbers

then

i'm gonna find the square of each of the

fibonacci numbers and add it

so if you see this

representation in excel

i'm going to generate

and these are the two variables which

i've already initialized x and y and

from

here on these

10

are my first 10 fibonacci numbers

i'm going to find calculate the square

of these numbers 1 4 9 25

and till 55 the square of 3 0 2 5 and

then add these numbers and i should get

the output of 4895 so if you see one

function generator second generator and

the third calculation now this hole

has been done in one single line of code

you have generated created two

generators

and just invoked them in a single line

pipeline

so entire looping

and you know

you don't have to write the looping

operators the for loop and you do not

worry about writing all that complex

logic it is all encapsulated within this

now let me run and i'm going to expect

this output 4895

and here is my output right so in the

hindsight what python has done is it has

generated these fibonacci numbers found

the square of these numbers and then

added it in single line

and now this is the convenience

simplicity which i was talking about

earlier

now let's take another example of

fibonacci

i'm going to create a generator again

initializing a and b with 0 1

[Music]

and this time i'm taking an example of

printing the fibonacci in two different

ways

okay

i'm gonna print

the first

five fibonacci series number

the first way i'm gonna do is i'm gonna

print

the next function five times because i'm

generating five

so let me run this

these are the first five fibonacci

number zero one one two and 3

and i am also going to use a

loop

in order to print

so now in the loop i am invoking the 5

fibonacci numbers

and run it

so either you can

make individual five individual calls or

you can use the for loop but the output

is the

same

and you are using a generator so what is

string formatting in python formatting a

string is something you will do all the

time when you are coding in python

string formatting also known as string

interpolation is the process of

inserting a custom string or variable in

predefined text

the string formatting methods

format the given string into a more

precise output in python

so it is the process of infusing things

in the string dynamically and presenting

the string now let's look at the

different types of string formatting in

python first one we have is using the

modulo operator so python uses c

formatting style string formatting to

create new formatted strings python does

that with the help of the modulo or the

percentage sign

this is the old way of formatting

strings this approach was more often

used in python 2.

so let's head out to our jupyter

notebook and see how this works

so this is my jupiter notebook that i'm

going to use for our demo

so let's start with our first example

that is formatting a string using the

modulo operator first i'll create a

variable called name let's see the name

is sean and i have another variable

which has the age of sean let's say 32

now i can create a variable called

string

equal to i'll say

hi

then use the modulo operator followed by

s

and i'll give an exclamation mark

give a space

i'll say

percentage

name

and then let's

print the string

if i run this

we have the output hi

shawn so what i did here was

we have defined the variables that we

want to format into the strings

then we have created the string with the

placeholders for the variables so this

is a placeholder

now the percentage s format specified

here tells python to substitute the

value of the

name

so hence we have high sean printed

now let's see another example

this time i'll directly use a print

statement

i'll say

i like

to

then i'll say percentage s

or modulo s

chocolate

ice creams i'll give a full stop

and then using my modular operator i'll

pass in my value that is eat so here

percentage s will be replaced by the

value 8.

now if i run this you have the message

here i like to eat chocolate ice creams

now you can also add

multiple strings at a time and you can

use variables to insert objects in the

string let's see one more example i'll

say string equal to say percentage s

is i'll say

percentage d

years old

then

i'll give a percentage symbol and say

name comma age

and let's

print the string

if i run this

you see here above we had defined the

variables name in age to be sean and 32

so here percentage s is for name so so

on

is

percentage d

is for age so son is

32 years old

so in this example percentage d format

specifier tells python where to

substitute the value for h

and it is represented as a string so

percentage s

is used to inject strings similarly

percentage d is used to inject integers

so here 32 is an integer and you can

also use percentage f for floating point

values and you can also use percentage b

for binary format

all right

now let's see another example

let's say i have a variable called x

which has

a value dance

i'll say

print

nancy

can

i'll say percentage s and

percentage

s

2

after this

we'll

specify

the parameters let's say x and

sing

if i run this

you have the output nancy can

so here percentage s is for x which

means dance so nancy can dance and

percentage s is for the second

parameter which is saying so my result

becomes nancy can dance and sing two

now similarly we can have another

example using

percentage f let's say i'll say print

the

value of

e

is

now i'll specify my format which is

going to be let's say percentage 5 dot

2 f close the quotation and then i'll

pass in my value for e let's say

2 4 5 5

3

dot

i am just taking random floating values

7 1 8 2 8 1. if i run this you see the

result my value for e is

24553.72

now let me tell you what

5

dot 2f means so here 5

would be the minimum number of digits to

be present in the string these might be

padded with white spaces if the whole

number doesn't have this many digits

and here 2f represents

how many digits are to be displayed

after the decimal point so after the

decimal point we wanted only two digits

so we have rounded it up and the value

is

seven two

all right

so coming to the

next type of string formatting in python

we have formatting with the format

string method

so python string dot format method was

introduced in version 2.6 now there are

two ways to do it one is using

positional arguments and the other is

using keyword arguments

so let's head over to our jupyter

notebook and we'll explore a few

examples on this before that let me just

give a

few comments so the first one we saw was

using

modulo operator now the second one is

not an operator this time we are going

to use the

format method cool

if getting your learning started is half

the battle what if you could do that for

free visit skill up by simply learn

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know more

so under format method we'll use empty

placeholder and replace them with a

string value

so

i'll write a print statement

let's say my

message is

welcome to now i'm creating

one placeholder which is empty you can

see here and let's say after that i have

tutorials

i'll give a full stop and then we are

going to use the

format method and inside the format

method we are going to

pass in the value let's say simply loan

so this

simply learned value will be substituted

in this empty placeholder

let's run it you can see the result we

have

welcome to simply learn python tutorial

so

this empty placeholder was replaced with

a string value that is simply alone

cool

now moving to the

next example so we'll be using index or

positional arguments inside the

placeholder

let me create a variable called s1

and i'll type in a message let's say

my message is let's

i'm using my first placeholder and i'm

giving a

position or an index

now in python you must be aware that the

index starts from zero

so i've used curly braces and passed in

zero i'll create another placeholder and

this time i'll put

index as one let's say my message

continues like this with

simply loan

and then

we'll use the format method

and we'll pass in the values for these

two placeholders

it should be width

let's say my value for the

zeroth index is

learn

and

my value for the first index is upscale

i'll go ahead and

print s1 and you can see the output

let's learn and up skill with simply

learn so here the zeroth and the first

index were replaced by learn and upscale

respectively so this is how you can use

index or positional arguments inside the

placeholders now you can also

add index numbers into the placeholders

to reorder values now this will affect

the order in which the method replaces

the placeholders let me show you so i'll

create a print statement

so let me create my first empty

placeholder and then i'll continue with

my message

let's say called

then i'll have my second placeholder

and i'll continue with my message to

inform that

then i'll have my third placeholder

will be absent

okay

now

let's use the dot

format method and we'll

have the values for all the three

placeholders let's see my first value is

luke

my second value is

dina and my third value is

john now if i print okay there is some

error here okay

there has to be another

bracket here now if i run it you can see

the message here

so the first placeholder was for luke so

luke called

dyna which is my second value to inform

that

my third placeholders value that john

will be absent

cool

now you can

add index numbers into the placeholders

to reorder the values now let me show

you how to do it i'll just

copy this

message and i'll print it here

and here i can now pass in my

index values let's say i'll add 2

0 and 1

so here

luke is for 0

dyna is for 1 and john is for second

index value now if i run it

now you can see the

difference in my message so here first

two comes which means john called

the value at zeroth index which is luke

so john called luke to inform that dinah

will be absent

all right

now let's see one more example this time

we'll be using name or keyword arguments

inside the placeholder in the earlier

examples we saw how to use positional

arguments

or index

this time we are going to use name or

keyword arguments inside the

placeholders

so i'll create

another variable called s2

and

i'll have my message let's see v

in my first placeholder i'll have the

keyboard as a then i'll have my keyword

as b my message will continue

i'll have my third place holder as c

with

simply loan

and then we'll use the

format

method

and then i'm going to pass in my

keyword arguments

so here we have to assign the value for

a b and c

so let's see the value of a is

loan

for b

let's say it

is upscale

and for c

let's say the value is grow

now

we need to

print s2

if i run it you see the message here we

have v learn

upscale and grow with simply loan

let's say we'll replace v with

let's

so the

message is more appropriate

so now you can see let's learn upscale

and grow with simply loan so this is how

you can use

keyword or name arguments inside

placeholders in the format method

cool

now let's look at the

third method we have

formatting with

string literals called f strings so

strings in python are usually enclosed

within double quotes or single quotes to

create f strings you only need to add an

f before the opening codes of our string

so this type of formatting is also

called as a formatted string literal

now when you

use f strings you need to display

variables so for that you need to

specify the names of the variables

inside a set of curly braces and at

runtime all variable names will be

replaced with their respective values

so let's go to our jupyter notebook and

we'll see a few examples

all right

now let me give a comment as

f

strings

okay

so

let's see our first example under

f strings

type

so i'll say

tutorial

equal to python

then i'll have another variable called

subject which has the

value

programming

next we have place equal to

simply loan

and then i am going to

use a print statement

and then i'll use my

f

keyword for f strings

and i'll say my

message as let's

learn

then using

curly braces i'll pass in my

variable name that i have defined here

first is tutorial then we have subject

from then i'll have the place

let's give a full stop and we'll close

the double quotes and let's run it so

here you can see we have our message

let's learn python programming from

simply learn so here tutorial and

subject

were replaced by python and programming

because we have defined tutorial as

python and subject as programming and

please we have a simply learn and hence

my message is let's learn python

programming from simply loan so

this is how you can use f strings so

when using f strings to display

variables you only need to specify the

names of the variables inside a set of

curly braces

you can also evaluate expressions

with python f strings let's see a simple

multiplication i'll create a variable

called n1 which has a value of 60 let's

say n2

has a value of 12

and i'll use my print statement

i'll give my

f keyword for f strings

i'll say the

product of

then i'll create my placeholders n1

and

next placeholder is n2 is

and then using

curly braces i'll do a multiplication

operation

that is n1 multiplied by n2

i'll close my

double quotes let's run it

so you can see here the product of 60

and 12 is

720 let's say i'll make it 10 and

40 if i run it the product is 400

cool

now you can

also use

f strings

in conditional statements

so you can use conditionals in python f

strings let's see

an example i'll create a variable called

num which will have a value let's say 55

then

i'm going to use a print statement

and use my f letter

and then i'll pass in my message is

number even

give a question mark then using

curly braces i'll have my placeholder as

true if

num

modulo 2 equal to equal to 0

else

display false

i close my double quotes

now let's print it

you see here is

number even the output is false because

55 is not even let's say i'll make it 50

and if i run it as number even the value

is true because 50 is divisible by 2 and

hence it is even all right

now coming to the

final type of

stream formatting in python we have

formatting with string template class

now template strings are provided as a

class within the string module of the

python library it is imported as a

module and the

dot substitute method is used to replace

the placeholders

now the format uses placeholder names

formed by the dollar symbol with valid

python identifiers

let's go to our jupyter notebook and

we'll see two examples on this all right

so this is the final section of our demo

let me give my comment as

template

string

okay

so first and foremost we need to import

the template

module so i'll say from string import

template now let me first run it i'll

create two variables the first variable

is a1 which has a value of

python

the next variable is a2 let's see the

value is

simply loan

then i'll create another variable called

n

which will have my template

function

and inside the function will pass in our

message

let's say

hello

welcome

to

now i'll use my

dollar sign and say let's say

n1

programming

so this is my template that i'm creating

by

again i'll say dollar

and two

give a full stop

now i'll say print

and

dot we are going to use the

substitute method so i'll say

substitute

n

1 equal to a1 so here i'm going to

replace n1 with the value of a1

and then i'll say

replace n2 with a2 all right

let's run it and we'll see the

result there you go so here my

output

becomes hello welcome to

now n1 we have replaced with a1 so hello

welcome to

python programming by n2

now n2 we have referred to a2 so

it becomes simply loan so hello welcome

to python programming by simply loan

now let's

see our last demo

again this is on

template

strings

so i'll create a variable called stu

name which essentially stands for

student name let's say the name of the

student is

johnson

then i'll create a variable called s and

i'll use the

template

function or the method i'll say hey

using the dollar sign i'll say

name

how are

you how are you followed by a question

mark

i'll say s dot

substitute

i want to substitute

this dollar name with sdu underscore

name

which has johnson

now if i print it

you can see the message here hey johnson

how are you

great

so

that brings us to the end of our demo

session on string formatting in python

what is scope in python

so scope in python is the area of the

region of a program where you can access

variables functions and objects declared

the scope defines the accessibility of

the python object so the objects cannot

be accessed from anywhere in the program

variables are not visible to the entire

code so their visibility can be

restricted

now scope verifies which variable to be

accessed

a variable declared inside a function

belongs to the local scope of that

function and can only be used inside

that function

now whenever you use a name such as a

variable name or a function name python

will search through different scope

levels or namespaces to determine

whether the name exists or not

so python resolves names using the legb

rule the legb stands for local

enclosed global and built-in scope

now talking about local scope

the variables which are defined in the

function are called local scope of the

variable so these variables are defined

in the function's body

now talking about

enclosing scope

now this scope only exists for nested

functions if the local scope is an inner

or nested function then the enclosing

scope is the scope of the outer or

enclosing function

coming to

global scope

the variable which can be accessed from

anywhere in the program is known as the

global scope

such variables can be read inside or

outside the function

now the global scope is often

implemented when we want to use the same

variable name in the rest of the program

coming to the

final rule which is b that is built in

scope so if a variable is not defined in

local enclosed or global scope then

python looks for it in the built-in

scope now this scope contains names such

as keywords functions exceptions and

other attributes that are built into

python

now if you define the same variable name

inside and outside of a function python

will treat them as separate variables so

two separate variables one available in

the global scope that is outside the

function and the other available in the

local slope that is inside the function

now let's head over to our jupyter

notebook and we'll try

scopes in python with hands-on

demonstrations

all right so i'm on my jupiter notebook

let's start with our

examples first we'll look at

local scope in python

for that i'm going to create a function

called

fun

and

inside the function i'll create a

variable called

s which

holds let's say

an object called

simply loan

and then

am going to

print

the variable that is s

now in this case i have defined my

variable

inside the function so this becomes

accessible only

inside the function

now if i call the function using the

function name that is fun

and if we run it you can see we have the

message printed that is simply loan

now

we'll see another example

so suppose

we'll try to access it outside the

function it will throw an error so i'll

just give a comment try

to access

it

outside the function

all right

so again i'll create

a function called let's say

fun 1

i'll give a colon and here i'll say

let's say

s1 equal to

simply loan

and now

i'll give a comment here print s1

then i'll call my function fu n1

and

i'll try to

print

the variable s1

outside the function

so here s1

has a local scope since it is defined

inside the function but i am trying to

access the variable outside the function

let's run it

you can see the error here name s1 not

defined now

if i give a

comment

and run this

you see there is no message and let me

just remove this comment and print it

you can see we have the

s1 variable message printed that is

simply known so this is how the

local scope of a function works

now let's see an example of

enclosed scope which is

function

inside another function

so i'll create a function

let's say func

and

i'll use the variable this time s2 equal

to

simply loan

and then

inside the func function i will define

another function let's say

i n f u nc which basically stands for

inside function

and then here i'll say print s

s2

and

we'll call the

inner function that is in

fu and c

and then i'll call the outer function

let's run it

and see the

result

you can see here we have the

message printed

simply learn i'll just

edit this message let's say

welcome to simply loan

now if i run this

you can see we have updated the message

here

now

for the enclosed scope you need to

define an outer function including the

inner function like we

did here

and you can also comment out the local

variable of the inner function and refer

to the variable using the

non-local keyword let me show you an

example around this

suppose i have a

global variable called msg

i'll say this is a

global

scope

message

after that

i'll create a function so i'll define a

function called

outer

and

i'll use the same variable name that is

msg

and my message would be this is

an

outer variable

after that

i am going to define another function

called

inner

and

this will have

the same variable that is msg and my

message would be

inner

message

variable

now as i mentioned before i need to

comment out the

local variable of the inner function so

i'll just

comment this out

and then

i'm going to say

non-local which is the keyboard

so i'm referring to the variable using

the non-local keyword

i'll say non-local

variable name that is msg

and now

i'll

print msg

will come out of the function and we'll

call it

inner

after that we'll call the

outer function

and then i'm going to print i'll just

scroll this down

and we'll say msg

so here what we are doing is so this is

an example of an enclosed scope so where

we have

defined the outer function enclosing the

inner function and we have commented out

the local variable of the inner function

and we are referring to the variable

using the non-local keyword now let's

run it you see here i have my

two

print statements working here the first

one is this is an outer variable you can

see here and then i have print msg so

this is a global scope message cool

now

we'll see an example of how the global

scope works though we have already seen

an example above so this was an example

of a global

scope

now we'll see a few more examples around

global scope again

suppose i have a variable called s3

equal to i'll say

simply loan

and then i'll declare a function

f u n c

one

i give a colon and then say

print

s s3

now i'll call the function fu and c1

and we'll print it

s3

if i run it you can see here i have

simply learned printed twice so i have

used the same variable name s3

inside the function so

this simply learn is for the

local scope s3 that is this one and

outside the

function we have printed s3 again so

simply learn twice

all right

now let me show you another example

about using the

global scope

create a variable msg1

let's say my message is

welcome to

simply loan

python

programming

i'll define the function f unc 2 i'll

give a colon

and i'll use the same variable that i

used

or declared above that is msg1

i'll say this is the

inner msg1 variable

then i am going to print msg1

after that i will call my function func2

and i'll print

msg1

if i run this

you can see i have the two messages

printed first is this is the inner msg1

variable and the second print statement

will print the

global variable

message that is welcome to simply known

python programming

cool

now you can also

use the global keyword inside the

function to convert a local scope into

global scope

now

i'll just give a comment using

global keyword

so i'll define my function func let's

say 3

i'll give a colon

and using the global keyword

i'll say

s

and i'll say s equal to

simply loan

now let me

call fu and c3

and will print s outside the function

now one thing to remember here

my variable has been declared inside the

function

but since before declaring the variable

i have assigned the global keyword to s

so this now becomes a

global scope variable so you can access

it outside the function as well now if i

run it you can see it here i have my

message printed

simply learn if i say hello you can see

it hello printed

cool

now

we'll see another example of using the

global scope

let's say i have a variable called e1

which is

india

and then

i'll create a function called my country

and i'll use

the

global keyword and say a1

and after that

i'm going to

say a1 equal to

i'll change the country to let's say

france

now let me

call the function my country and will

print

a1

and you can

notice the difference in the result

so here initially i had defined india as

a global variable and after that i am

assigning the

same variable name with a global keyword

and hence it will take

the updated value for e1 and you can see

here the result is france

now finally let's look at

built-in scope in python

this is the final example in the demo

session about scopes and arguments in

python

cool

so

this example is a bit different from the

previous few examples that we saw on

local scope

enclosed scope and global scope

so here

i'm going to

import

pi from the math

module so i will say from math

import

pi

so this example includes

global scope enclosed scope as well as

local scope and of course we have the

built-in scope as well

now what i'll do is

first i'll

give a comment and

create a variable called

pi

equal to

i'll say

global

pi

variable

i'll say this is a global

pi variable

and then

what i'll do is i'll say

df

let's do one thing first of all we'll

remove

the comment

and now i'll create a

outer function

into the colon and say

the variable pi

i'll say

outer

variable

pi

and then

i'll create

a nested function

with the name inner

and

i'll say pi

equal to

inner

pi

variable

now

i am going to say

print

pi

and

after that i will

call the

inner function

and

next

i'll also call the

outer function

now if i

run this

you can see the result

inner

pi variable being printed which is this

print statement

now

what i'll do is

i'm going to comment out the

global scope variable

and i'll also comment out

the first

outer function variable that i defined

i'll comment this out

and i'll also comment the inner

function

pi variable

now

if i run this

you see the result here

it prints the value of pi that was

imported directly from the math module

or the math library

so here pi is not defined in either

local

enclosed or

global scope so the built-in scope is

looked up that is the pi value imported

from the math module so this is an

example of built-in scope in python that

uses

inbuilt

functions modules and objects that are

available in python

all right

let's glance at the

topics object-oriented programming in

python some major principles of

object-oriented programming and then we

will touch upon topics like class in

python objects

methods

inheritance

the concepts of inheritance the

different type of inheritance then the

definition and examples of polymorphism

encapsulation and abstraction

so all these topics will be

supported with examples

and the relevant terminologies and

definitions

now what is object-oriented programming

python is an object-oriented language

like any other programming language like

java c

and the object oriented programming

language concept is not new

and each and every mature programming

language

has these concepts imbibed in it

now the concept of object oriented

programming in python focuses primarily

on creating project objects and making

reusable codes so whenever we start

programming at a large scale or for a

big project it is very important to

identify the objects within that

particular project which you want to

define

now for example in this

in this

presentation what you are seeing is that

we are covered with full of objects like

car

dog tiger tree or a balloon so these are

typical examples of objects which you

encounter in day-to-day life

now what are the major principles of

object-oriented programming so these are

the different kind of you know

terminologies

classes are there there are objects

there are methods

then on these classes and objects you

apply inheritance polymorphism

encapsulation and abstraction

now what is a class

class is nothing but a collection of

objects or we can say a user defined

data type right so basically it's a

complex data type which has a collection

of objects and within the objects you

have primitive data types like in string

float etc

so a class also holds the methods

the functions

which basically perform operations on

these objects

right and also it also holds on to the

attributes of the objects so let's see

with an example right

so if you have an employee class

then it would contain attributes and

methods such as email id name age salary

these are the attributes and on the

methods like you know perform tasks give

presentation

increase salary

etc etc these are will be the methods

now let's talk about what are objects in

python

now object is known as instantiation of

a class right an object is a group of

interrelated variables and methods

so when a class is defined only the

description for the object is defined

therefore no memory or storage is

allocated at that point

so for example if you see in this

motorbike is a class

but

the different objects of the class are

different kind of bikes by different

brands like bmw suzuki royal enfield so

they all have inherited the attributes

of the class motorbike and then on top

of it defines certain variables

additional variables and methods

on top of it to enhance the motorbike

and make it look different or function

differently now what are methods in

python methods

are functions defined inside the body of

a class right

so basically methods are something which

like

which you which you perform on a

attributes of a class right method is a

function that is that is associated with

an object

so you create an object of a class and

on that object then you can execute

those functions

in python a method is not unique to

class instances

any object type can have methods

and the methods define the behavior of

an object so that's why a bmw motorbike

will be different from royal enfield

because the behavior is different the

methods are different

so if you see the example over here you

have a class bike

and in that there is a init function

which will get invoked when you

initialize the object of class bike and

then you can set the brand name and the

year of manufacturing for that

particular object

now inheritance

what is inheritance inheritance is

something which you derive

from a

parent so inheritance is like creating a

new class that uses all the properties

and behavior

of another class

now the new class is called the derived

class or the child class and the

existing class whose properties are

inherited is known as a base class or

parent class

it provides and the basic view

functionality the usage of inheritance

is that reusability of code

so if anything is defined in the parent

class then you don't need to rewrite

that particular code in the child you

can just inherit it

so as i mentioned let's take a look at

the different types of inheritance which

are available

you have single level in which only one

child is inheriting

the properties and the attributes from

the parent

then you have multi-level in which

first child has inherited from the class

a class b has inherited and then you

have another class c which is inheriting

from class b so this is an example of

multi-level and we will be supporting

all these concepts with an example in

our python

uh notebook

then there is hierarchical then there

are two different classes which are

inheriting from a single class

and then multiple inheritance that

single class is inheriting from two

different parents

so these are different set varieties of

inheritance basis what is the demand

what is the business requirement you can

define

now what is polymorphism polymorphism in

python

what does it means

polymorphism consists of two words poly

and morphs

poly means many and morph means shape

so basically it means

many shapes

so it is it means using a familiar

interface for multiple forms right so

you can use

a single name of the method and which

can perform different behavior

based on the object in which it is

invoked so in simple terms we understand

that a task can be performed in various

ways

let's support it with an example

like you have a plus operator now the

plus operator can be used for integer

data types to perform arithmetic

operations

whereas when you use plus operator to in

string data types it can be used for

concatenation

so it's a very typical example very good

example in terms of

how an uh

same operator

can behave differently bases what data

types are being used

now let's talk about encapsulation

using oops in python we can restrict

access to methods and variable

so basically in

in python you can you can create

something like as private

variables but of course you can't use a

private keyword unlike java so in in

python we use underscore or double

underscore in order to define private

attributes so basically

these attributes can be only used within

the class and cannot be exposed outside

a particular class

so we will see this with an example

now what is abstraction data abstraction

and capsule encapsulation are often used

as synonyms abstraction is used to hide

internal details and show only

functionalities

for example

you know how to turn on or offer light

using a switch but you don't know what

is happening behind socket similarly an

abstract class can not be instantiated

which means you cannot create objects

for this class you can only

define

the methods

which have to be implemented by the

classes which are inheriting the

abstracting

so basically abstract class provide only

the method signatures

and rest the other functionalities and

the implementation has to be done by the

child classes

so let's now move to the

our

jupiter notebook and we will

start performing certain examples

now as we are saying

like python has objects so let's create

object

we will create a class

bikes over here

and within the class

we will define the init method

and

in the init

we will

instantiate two variables brand name and

here

now

we will create an object

of

bike

which we we are calling as bmw and

another we will create an object called

ducati so what we are doing in this

to scenarios is

that we are

just instantiating the byte of bike

object with

variable bmw and ducati we are

instantiating

now

let's

print

the

year and manufacturing here the brand

name and the ear

for bmw and for ducati and let's see

right so what we have done is we have

created an object for bikes one we are

calling bmw and one we are calling

ducati and how we are differentiating

between these two bytes is basis the

brand name and the year of manufacturing

now

let's take a look at the example of

methods

i'm gonna

rewrite my init method

and now i am

creating an

function

a method

of top speed

and

a function of type

now

i'm gonna

create an object of bike

now this

method this object bike

can invoke methods top speed and type

because they belong to the same class

bytes

so initially when i created my object

bytes i'm instantiating it with bmw and

the ear

and then

i am

making a call to the

method top speed and then i'm making a

call to the method type

and printing

so basically i'm printing the output of

the function top speed and output of the

function bmw

form the object bmw which is of class

bikes

now let's take a look

at an example of single level

inheritance

let's

create a parent class called animal

and

create a

method called sound

and let's create a child class

cat which inherits

animal and let me just put a method over

here

is the indentation

okay

so now i have

object

parent class animal child class cat

which has inherited animal

and the parent class method is sound and

the child class method is meow so now

i'll create an object called cat

and with this object

i'll be able to invoke both child class

method and the parent class method

and as you can see

the child class

has inherited both

parent and child

class functions methods

now let's take a look at

multi-level inheritance example

i'll start off

with creating exactly the same

parent class called animal

then

i am i am already created another class

i'll create

same child class cat

and

now i'll and create another

class which will inherit cat class

so cat has inherited animal and cat

child has inherited cat

let's validate its syntax

and similarly now i'll create an object

for cat child

and this cat child now

can

invoke the same methods

which are in child

parent and the

super parent

so this is an example of multi-level

this is an example of

single level inheritance

now

let's take an example of polymorphism

we are going to click create a class

parrot

and define the function fly

and

now we are gonna create another class

mind you there is no inheritance here we

are just creating an independent class

called penguin

and same methods now the same name

fly

and

swim

okay

now let's make a

function

in which we will pass

an object

and basis

that what is the instance of the

particular object bird it the

corresponding method will get invoked

so let's see

in the method flying test

whatever instance of the bird object

will be the corresponding of method will

be called

so now let's create a

object of parrot class and then

let's create a object of penguin class

now in my flying test

method

first i'll send a object of instance

parrot

and then

i'll

send the object of instance penguin

so now base is the instance type

when this bird dot fly

method will be called it will be

called basis the instance so in the

first case the parrot it will call this

method

and in case of penguin it will call this

method fly

so please note what is the output the

output is a parrot can fly but a penguin

cannot fly

and it has been decided

by the python

at the run time that which particular

method to be invoked bases the instance

so it's a very important concept

now let's take an example of

encapsulation

i'll make a class cars

define its init method

now within that init method i have

created a

private variable with underscore

underscore max price and given a value

of

9 lakh

now i am creating another

function called sell

and in that i am printing the

max price

and then

i am creating another function in which

i am modifying the private variable set

max price

so i will pass any value in the set max

price and it will replace the max price

which i have set during the

initialization at this point

now let's create an object of class cars

and

see if i sell this then the selling

price is

9 lakh what i had in the set at the time

of initialization

now what i'm trying to do is i'm trying

to modify a private variable

directly

c underscore underscore max price

and i i want to check

if i'm trying to create a modify a

private variable

will it still show me 9 lakh or 10 lakh

value and it's still showing me the 9

lakh value it means that i can't

directly

approach or access the

private variable

i can only modify it

if i access it through a

method which is set max price in this

now i am setting the max price to

thousand

and now if i print what is my max price

it will print as

thousand

so this is the concept of encapsulation

you have a private variable which is

accessible within only the methods

of the

class you can't access it directly

now let's take a look at archaeal

inheritance

i'll create a class employee

and

create init method

within that you have

three variables name agent salary so an

employee with has name agent salary

now

i'm going to create a class

child class called child employee 1

which is inherited from employee

and child employee 2

which is also inherited from

employee

so what i'm gonna do is i'm gonna create

a

object

per child class

and

print

so this is a typical example in which

you have two child

classes which have inherited from the

single parent

ark in narratives

now let's take a look at

our last concept which is abstraction

so now i'll create a class car

and define a method

mileage but i am not

giving any definition to it i'm just

giving a signature mileage

the child

classes which will inhibit abstract

class

will be giving the definition

so i am giving

creating a class bmw

which will again

which has inherited the car abc car but

given the definition now

similarly

i am creating another class

jaguar which has inherited the class car

but now it is giving a different

definition

it's printing mileage 25 kilometer per

hour

and

another class

range rover

and another class

renault

okay

so four classes

which have implemented the abstract

class method mileage in a different way

now i'll create an object of first

bmw

and

invoke method

mileage

so it has method invoke the method

mileage and bmw car and printed mileage

is 30 kilometer similarly

i'll do for renault

jaguar

and

range rover

so if you see

the

parent class

abstract parent class has not

implemented the method but just given

the signature of the method and all

other classes have implemented it and

that's the concept of abstraction

so what's in it for us today

what we will understand what is operator

overloading

and how to overload the operators in

python we will perform these activities

in the jupyter notebook

now what is operator overloading

python operators work for built-in

classes in a predefined operational way

but the same operator behaves

differently for objects of different

classes

so you can make the operator work

differently

bases the requirement you have and the

objects you have defined

so for example the plus operator which

is the most commonly used operator will

perform arithmetic addition on two

numbers or it can merge to less

or if performed on two strings it

concatenates the two strings so it means

the programming language automatically

understands that in which context you

are using the plus operator

this feature in python that allows the

same operator to have different meanings

according to the context according to

the objects which are calling it or

according to the data types which are

being used in that operator it is called

as operator overloading

so if you see in this example 8 and 7

are the operands and the plus sign is

the operator sign

so that is the whole goal of this whole

exercise that we will show you

how you can change

the meaning of the plus operator

depending on the kind of objects or kind

of operands you're using along with it

now how to overload the operators in

python

consider we have two objects b1 and b2

of a class batsman

now we must add these objects with a

binary plus operator

so now the task in hand is that we use

the plus operator to add objects which

is not possible until and unless we

overload this operator

otherwise it will throw an error because

the compiler does not know how to add to

objects it only knows how to add

primitive data types like in strings etc

so basically we will define a method

for an operator that process and that

process is called operator overloading

so in the example which we will be

showing you we will be taking two

objects of batsman 1 and batsman 2 and

we will be using two scores per patchman

and then we will add them so we will

discuss that in the examples we will

show you

now

we can overload all the defined

operators so there's no limitation

addition subtraction multiplication

division

greater than less than so there are

certain magic methods or we can call it

as the primitive methods or special

functions

that are automatically invoked when an

associated

operator is being called

so basically if you have to do the

operator overloading

you basically have to override these

methods in your python program

and that's how you will be able to

override or overload the primitive

implementations

of these functions written in the

compiler of python

so

let's see here in our example right for

example when we use the plus operator

the magic method underscore underscore

add underscore underscore is

automatically invoked

in which the operation for the plus

operator is defined

now we are overloading it and in the

example you can see

we are adding

the

first score of each batchman right so we

have customized the addition function

we are adding the first score of the

first baseman with the first score of

the second batchman and then we are

printing the total so in our case we are

adding

and printing the first one 66 plus 23

and if you print b3 dot s2 you will see

the sum total of 78 plus 59

so the thing to be noted is this

function add function where you are

adding self dot s1 plus second dot s1

and you are adding s self dot s2 plus

second dot s2 and that is the whole

customization what you have done in

order to add two objects of patch

now lets take a look at some of the

examples of operator overloading we have

just discussed

so we will be executing some examples in

our jupiter notebook

now

what i am going to show you

is about

class batsman which we discussed in the

presentation

and i'm going to define the init

function

and

initialize

score 1 and score 2 of the attachment

now

i am going to override

the magic function add

and

add the score 1 and score 2 of the

batsman separately

now with this over

operator overloading

when i will pass

object for addition

then only now my object will understand

that it has to add

score one

of first batsman with the score one of

second batsman

and score two of first batsmen with the

source code two of the second batsman so

we will see how

so what we are doing is

one in the add

operator

we are adding these codes

encapsulating in a new object batchman

and then returning the

object b3 now let's create

object b1

batchman1 and batchman2

now i am

adding two objects batsman one and

batchman two

now without operator overloading if

would i would not have done operator

overloading of add then this would have

failed because plus operator does not

understand the object's batsman but with

overloading done

now i can independently print the score

of

the new batsman the batsman's the b3

object

some of score one of batsman one and

uh score one of batsman two which is 66

plus 23.

okay

so now let's take an example of a simple

operator function

like for example i'm gonna

simply create a variable a with value 44

and variable b with 7

and

print a plus b and if i run this

this is the expected output

python plus operator knows that a and b

are

primitive int variables so it's able to

add that

now behind the scenes when we printed a

plus b

actually this is what happened

in

primitive in variables add operator

overloaded method got called

and a and b got passed and 51 was

calculated

so it's automatically done because this

function is implicitly written in the

python language

similarly

i can also do this thing i can create a

int variable

and a float variable

and if i try to print it

i will get the expected output which is

50.5 because the plus operator accepts

the end and a float variable it's

implicitly written so that is also

allowed

now let's take another example of

string operators

string variables

addition

now irrespective of my

i'm giving numerical values in the

string print a plus b

in string

is is meant to do concatenation

so

446.5 it's a simple string concatenation

what python has