Geocoding is a key step in creating interactive heat maps; Tableau has a geocoding tool that is more efficient than the geocoding functions of Mapbox and Fusion Tables.
To create heat maps, popular mapping tools such as Tableau, Mapbox and Fusion Tables all have built-in geocoding functions; but in comparison, Tableau can automatically recognize many of the common areas such as countries, states, cities, regions, or even area codes, whereas the other two mapping tools would require separate KML data.
This chart is a simple data set showing some values for regions in Spain. To make it into a heat map, a mapping program needs to (1) know the texts in the “region” column describe locations, (2) plot the regions onto the map and (3) add data to associated regions on the map.
And in this process, step (2) is called geocoding, which is to transform a description of a location to a location on the map; the location descriptions can be coordinates, street address, postal code, name of place, custom-shape polygons, etc.
In the case of Tabluea, we can specify that the region column in the sample data set contains geographic data, and Tableau will automatically match the column entries (region names) to actual locations. Due to variations in writing, Tableau needs a bit help in matching some names to actual regions. And below is the finished interactive map.
When we load the same data set to Mapbox, it does not recognize the regions as within Spain, and plots them spreading several countries, as shown in the screen shot below. And there are no advanced settings, similar to those in Tableau, where we can “instruct” the program how to plot the geographic data. In the case of Fusion Tables, Google can recognize and plot all the regions without additional instruction, but it can only plot the regions and data as markers, not areas, as shown in the screenshot: To plot the regions the way we intend, Mapbox and Fusion Tables both need a separate KML file that describes boundary information of these regions. Obviously, the automatic geocoding feature in Tableau saves us the hassle of having to hunt the web for that KML file – if there is one. If you are interested, here is a short video I created for my data visualization open course; in this video I demonstrated how to use the geocoding feature of Tableau to plot regions in the sample data set. Note in this video I left out Balearic Islands to focus on the mainland of Spain.
Want to learn more about geocoding? Here’s some popular books on Amazon that you can check out:
- Annotated Tableau tutorial video: A quick start guide for instructors and first-timers
- Google maps tutorial: How to create a free heat map with Google Fusion Tables
- Google maps tutorial: About KML/KMZ geographic files
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