All language subtitles for 02_working-with-tables-in-arcmap.en

I'd like to show you how to work with tables inside of ArcMap.

This might be adding a new field,

also known as a Column,

it might be performing a calculation on that field,

it might be calculating the geometry, in other words,

the area or the perimeter of something,

or it might be actually joining two tables together.

So, let's have a look at how all that works.

So, here I have a very basic map of North America,

and I'm just going to add in two datasets,

one of them is called Provinces which is actually provinces and territories,

and a table here called Prov Pop

which is the populations for those provinces and territories.

So, you'll notice that, a couple of things,

one is that it automatically gave

my provinces and territories green color which is yeah, it's okay.

It's not fantastic, but I guess we can live with it.

Then secondly, because I added in a table that's not a GIS mappable file,

it automatically switched to the list by Source View.

So, you'll see here that the little icon indicates that this is a table.

So, this table, if I go back to this side,

you'll see that's the same table there.

It is in fact,

inside a file geodatabase.

So, it is in a GIS file format,

but there's nothing in that file,

in that table, that allows the software to automatically map it.

In other words, there are no coordinates associated with that dataset.

It's literally just a table with some fields and records.

So, one of the things we're going to do is map that by joining it

to the provinces feature class that is mappable, but we'll get to that.

Let's do this one thing at a time.

So, one of the things I wanted to point out is that,

in this list by Source View,

you'll see that we have two file geodatabases being used.

This is one I created with my data for Canada,

and this is a separate file geodatabase I have with some base map data for the world.

So, just country, graticule, or water.

So, I just put that in a separate file geodatabase.

You can have it in the same one. It doesn't really matter.

But the main thing I wanted to point out here is that,

often if you're new to the software,

when you add a table in,

you may not notice that it's not listed.

If I go back to Listing by Drawing Order,

you'll see that that table doesn't appear there

because it's not something that can be drawn.

It's a table. It's not something that's mappable.

So, often people will add something and going to go, "Where to go?What happened to it?"

Well, it is there. It's just not under that tab.

But if you go to this one, List by Source, then you will see it.

So, it's showing us that there's two different sources here,

two different file geodatabases,

and it's listing all of the tables, feature classes,

et cetera that we have,

based on where they're located,

what source they are in.

So, you'll see here,

for example, that both of these are on my Z drive,

just in the root folder,

and it's listing them according to their location.

Okay, so for example,

we can open up the Attribute Table for provinces,

and you'll see that we have some different fields here.

So, the object ID field is added automatically by the software,

that's something that the software uses to keep track of all of

the objects or records or things inside a data file.

I would highly recommend that you just ignore it.

It's almost never going to be used by anything by you as a user.

I'm honestly not even sure why they show that but they do.

Then you see a column here that just says polygon or the name of the shape,

that links to the actual coordinates for this feature class.

You can't see them, you can't access them.

Again, it's a column and I'm not sure why they show it to you,

other than to state the obvious that these are polygons.

Then we have the fields that belong to this table.

So, we have province and code.

Those are the two main ones, and then we have two fields here that are

added automatically because it's inside a geodatabase.

So, it's automatically calculating the perimeter and the area of each of these objects.

You can see these are quite large numbers,

and my guess is that,

that these are in meters,

and so they're not necessarily the most useful numbers for us.

So, I'll actually show you how to calculate

your own area values in the units that might be more useful for you.

It's very easy to add a field to a table.

You can just select here,

in this little icon in the corner.

Select Add Field, and then you'll be presented with

this dialog box where you can name the field whatever you want.

So, in this case, I will name it Area.

You have to know the type of field that you want to create.

There are different ones available.

So, some of them,

like the integer ones don't have space or storage space available for decimal places,

other ones, like Float and Double do.

So, in this case, I'm going to go with Double.

It's a safe bet you usually use,

and if you want you can use an alias.

So, what that is, it's sort of

a longer name that doesn't have as many restrictions on it.

For the software, it's just a way of having a more user friendly name if you want.

So, for example, here I could say area parentheses sq km parentheses.

So, for example, those parentheses aren't allowed in the actual real field name,

but they can be used in an alias.

It's just the way the database is set up, so it's just a little tip.

So, if I say Okay,

you'll see that it's automatically using the alias as the header,

but the actual technical real name for that field is just Area.

You'll notice that it's filled with nulls.

So, even though I said area,

even though I said square kilometers,

the software is not a mind reader.

It doesn't know that that's what I want to calculate.

So, I have to then tell it how to do that calculation.

We can just right click on that and say Calculate Geometry.

So, we can choose the property that we want to calculate.

In this case, it could be Area,

Perimeter or the Centroids which is

the x and y coordinates for the center of each of the polygons.

I'm just going to stay with the Area,

and then it will ask me which coordinate system I want to use.

Unfortunately, I've already chosen

a projected coordinate system that's an equal area projection,

so that when I calculate areas,

they will be calculated correctly because I'm using one where there's

less distortion and the areas are better

maintained for the size of the area that I want to do the calculation for.

So, then we can go down to the units and select those.

I'm going to select Square Kilometers,

and that's really all there is to it.

So, now if I click Okay,

it's actually calculating the area for every polygon.

It's looking through all of the geometry,

the vector, coordinates, doing that calculation.

So, now we have our result down here where we

have the area that I've calculated in square kilometers.

So, you'll see here, for example, that this is,

what is it, 663,196 square kilometers.

So, I'm guessing that I was right that

that's in square meters because the number is basically the same.

It's just the decimal places moved

because that's in square meters versus square kilometers.

Okay. So, this is easier for us to work with,

square kilometers is a more intuitive unit when

you're talking about areas as large as these.

So, now we figured out how to add a field and we've performed to

Calculate Geometry functions so that we know the areas of the provinces and territories.

Now, what if I'm interested in calculating

population density or even knowing what the populations are for each of these?

You'll notice that in this attribute table,

I don't have population in there,

but if I open up my Prov Pop table,

as you may already have suspected,

I do have population values going from 2001,

2006, 2011, and I have a code

here which corresponds to the code column in my provinces table.

If I switch back to that,

you'll see here, I've got a code field here,

and the same code field here,

and so I can actually use those to join those two tables together dynamically,

and what that will basically do is,

allow me to treat them as though it's one big table.

It's not being stored permanently that way.

It's just something that's being done on the fly.

I'm telling it to treat those two tables as though they're joined

together and then we can use the population data from

my non-GIS table with

the province geometry or the polygons for my provinces feature class,

and then I'll be able to map the data from

the non-GIS table into the one that is mappable.

I'll show you how that works. So, I right-click

on the table that I want to join, the table two.

So, I'm going to select Joins and Relates, Join.

I'm going to join based on the attributes from a table,

and I'm going to use the code field for that and then I'm going to join

the Prov Pop table to my provinces feature class,

and it just so happens that I've named the field in the Prov Pop table the same thing.

So, it's code. It doesn't have to be.

As long as the entries correspond correctly, that's fine.

I could've called it anything I want.

I just made it simple so that they both match up.

But just so you know, they don't have to match in terms of the field names.

They do have to match in terms of the field type

and the entry so that they match up correctly.

I'm going to say keep all records and click Okay.

So, now if I go back to my provinces table,

you'll notice that not only do I have all the original data I had from

the provinces feature class but it's added onto the end,

the data from my Prov Pop table, okay?

So, now that's not permanently attached to it.

It's just there dynamically,

is one way of thinking of it virtually,

so that it's pretending if you want that that

data is attached to that table but we now have access to it.

So, let's see. If I go to Provinces and Properties,

Quantities, Graduated colors, I now have access to that

population data from my non-mappable table.

So, now I can map it, which is great.

This is a very common function.

It's not the only time you want to join tables together,

but it's a very common thing where you found data in an Excel table

or a CSV file or some other format that's not a GIS format,

and you want to be able to bring it in and then make use of it in your GIS software.

So, joining tables is one way to be able to do that.

Now, of course, I don't really want to make a choropleth map of just population.

I want to normalize it,

and so, I can under normalization,

use the area that I already calculated and say Okay.

So, now I have population density choropleth map done for the provinces and territories.

So, I was able to use my Spatial Join,

I added a field, I did field calculation,

or Calculate Geometry, and so, now we have that.

Actually, speaking of field calculations,

let me just show you quickly how that would work,

as if I wanted to,

I could add a field, call it Density.

Again, I'll make it a Double,

and I'll just leave it at that.

If I wanted to actually calculate density,

I can say Field Calculator,

and then you'll notice that it says provinces dot and then the name of the field, right?

So, Provinces.Code and so on.

That's telling you that those are fields that belong to the provinces feature class,

and if I scroll down,

you'll see that there are also fields that belong to the Prov Pop table.

So, I'm able to access both sets of fields,

and it's just indicating to me which fields belong to which table.

So, I could say population 2011

divided by area, say Okay.

So, now that's going to do a calculation to populate the fields that I call density,

sorry for the pun there I suppose.

So, now I have a permanence calculation that's been done here,

so that that's my population density values for each of the provinces and territories,

and you'll see that it says Provinces.Density,

so that it's indicating to me that that density calculation was

done on the provinces feature class.

Okay, so that's how you do a field calculation.

So that's basically it.

Just a quick overview of how to work with tables.

So, joining them together,

adding a field, doing a field calculation,

and calculating geometry so that you can take

data that's not mappable and turn it into something that is mappable,

or maybe you want to do a calculation for

any other reason but whatever it is, now you know how to do it.