8. Introduction to Maps

Overview

Maps are one of the most powerful visualizations in Tableau and are relatively straightforward to create. In this lesson, we'll use maps to plot revenue by state.

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Summary

How are maps generated in Tableau?

- Geo-coding is a process that turns addresses into latitude and longitude co-ordinates
- Tableau tries to automatically geocode as much as possible to make maps easy to generate
- Data fields such as State, Zip and Country will automatically be geo-coded by Tableau
- These data fields appear with a globe icon next to the field name in the data pane

Types of map

- Tableau has two types of maps to choose from:
--- Fillable maps: regions are color coded by a dimension or measure
--- Symbol maps: individual points are plotted using different symbols (e.g. dots)

Transcript

One of the most powerful visualizations in Tableau is the map. Maps provide fabulous context for a viewer, particularly when your product or service is somewhat dependent on location. For example, if your sales team have different territories or if you've just launched a product in a new region, maps can offer much more intuitive visualizations than a line or a bar chart. Before we start creating maps in Tableau, it's important to understand how mapping locations are generated in software. Typically, when we interact with any mapping software, we need to perform a task called geocoding, which is a process that turns a postal address into longitude and latitude coordinates. So, for example, I might have Grafton Street and this turns into two numbers signifying latitude and longitude. Thankfully, Tableau tries to circumvent this problem by providing instant geocoding within its platform. When we load geographic data into Tableau, you might see a globe icon appearing next to these dimensions. So on the left-hand side, we can see this for city, state, and zip code. From these columns, Tableau can generate a latitude and longitude set of coordinates to be used on maps, and this runs in the background. Let's see Tableau's geocoding in action by dragging state into columns and we can drag revenue into rows. And with this dimension and measure, I'm now going to create a map and I'll go with the field map. And unfortunately, when I click on this option, nothing happens.

And I see a sign in the bottom right-hand corner telling me that I have 45 unknown values.

Let's click in here and I'll edit locations.

And it's quickly apparent what my problem is. The states in my data session are US states, but my country or region is the United Kingdom. So let's switch this to the United States and then press OK.

And when I do this, I now get a nice interactive color-coded map.

On the left-hand side, we have a number of controls that can be used with the map. The first of these is a magnifying glass that allows you to enter an address on the map, for example, New York City.

Below the magnifying glass is a plus sign which allows you to zoom in onto the map and a minus sign that allows you to zoom out.

If you zoom out too far, you can simply use the pin to reset the map back to the original dimensions like so.

If we hit the arrow, we see a couple of more controls starting with zoom area. This is probably one of the most useful commands you'll use with maps. If I select zoom area and really want to avoid Alaska because it's really obstructing my map, I can just select the 48 states in the mainland and now my map zooms in on this area.

To move the map around, I'll use the pan tool and this allows me to drag to the left and drag to the right.

The remaining three options are selection tools in different shapes: rectangular, radial, and lasso.

I tend to use the rectangular as a rule which can be useful if I'm selecting, for example, just the states on the West Coast.

Obviously, we also have our marks card for maps as well. Say, I'd like to include the revenue for each state.

I go to revenue and add it to label.

And this now appears for each state on my map. Let's change this slightly to only show the revenue for selected states.

And now when I just select, say, Texas and California, revenue for both of those states pops up. To get some practice with maps, try testing out some of the controls on the left-hand side and playing with the different marks to see how you can make your maps more interactive and readable for users. In the next lesson, we'll delve deeper into the uses of maps, focusing on both symbol and fill maps from Tableau.

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Tableau Essentials
Creating Visualizations in Tableau

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