How to use Buffer Calculations In Tableau 2020.1

0:00A new addition to Tableau 2020.1 is the

0:05buffer function for spatial analysis.

0:10Essentially this allows you to draw a

0:12radius around a particular spatial point

0:14and then

0:14visualize that in Tableau.

0:17In order to do that, what I've actually

0:18done is I've generated some mock data from

0:20Mockery with essentially the name of car

0:23companies and I've got a latitude and long

0:26itude for

0:26the corresponding address.

0:28So if I head on over to Tableau and I open

0:31up my text file, I'll connect to that

0:35sample

0:35file that I downloaded from Mockery and you

0:38can see here that I get the name of the car

0:40company, the address, but critically I have

0:43a latitude and longitude available to me.

0:46Now what I can do is I can actually give

0:48these specific geographical roles.

0:50So you can see this has already got

0:52latitude.

0:53So let's go ahead and give this one a long

0:55itude as well so that when we get into Table

0:57au we

0:58can just start working with it straight

1:00away.

1:01Let's open up the sheet and you can see it

1:03's a very simple data source.

1:04It hasn't got many column names in there.

1:08One of the things we need before we can use

1:11the buffer function is we need a spatial

1:13object

1:14for it to work with.

1:15So I have to create a point.

1:18Latitude and longitude are good if you're

1:20trying to create a map of where something

1:22is but it's not actually a spatial sort of

1:25data type in itself.

1:27It's just describing where something would

1:30be.

1:30So in order to do that I use one of the new

1:32functions that Tableau added in 2019, make

1:36point, and all I need to do is drag the

1:40latitude in there and then drag the long

1:44itude and then

1:46I can just call this car dealership and hit

1:52apply.

1:53So now that we have our car dealership if I

1:55double click that you'll see that Tableau

1:57maps those in the correct way.

2:00Now I want to remove that because what I'm

2:02actually more interested in is the buffer

2:04calculation.

2:05So let's create that here by creating a new

2:08calculated field and I'll just zoom in so

2:10you can see what I'm typing.

2:12In order to invoke the function you just

2:15need to type buffer and you'll get this

2:17sort of

2:18field and the key thing here is anytime you

2:20type any function in Tableau it always

2:22gives

2:22you a hint as to what it's expecting next.

2:25So it's expecting a geometry next.

2:27So the geometry is this spatial point that

2:30we've created.

2:31In other cases it might be a line, it might

2:34be a polygon, whatever it is you can add

2:36that

2:36here into Tableau.

2:39The next thing is the number.

2:40So this is essentially the radius of the

2:43particular point we're trying to draw.

2:46So I'll do 20 kilometers and I'll also

2:49describe the units as kilometers.

2:52You can see here that in the example Table

2:53au uses kilometers but you can of course use

2:56other units if that works a little better

2:59for you.

3:00So then what we'll do is we'll just call

3:03this a buffer calculation like so.

3:06If I hit apply you'll see that my buffer

3:08calculation appears here on the left hand

3:10side and then

3:11if we double click that you'll now see that

3:14I get a circle that represents the total

3:17radius

3:18around the particular point that I was

3:20talking about.

3:20So if we zoom into particular areas of the

3:24map and just pane this further down you can

3:27actually start to do some analysis as to

3:29where specific radiuses overlap.

3:32So here for example if I look at these

3:34three dealerships, if I just bring in the

3:36company

3:36name onto color you can more clearly see

3:39that these three companies here overlap and

3:42if

3:42I play around with the opacity I can

3:45actually get that to work in a nice way.

3:48So that's a very very simple example of how

3:51to use the buffer function in Tableau.

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4:01in the future.

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