Google Chart API’s New Schematic Maps

Raymond Yee, April 11th, 2008

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Graphic, schematic maps can very useful in a wide range of charting scenarios and thanks to a recent upgrade, now you can use the Google Chart API to create them. As we reported earlier, Google’s Chart API is one of the simplest of all Google APIs. By passing parameters in the URL (i.e., HTTP GET), you can get images for various types of charts — bar charts, pie charts, line charts, etc — that you can embed on any web page. Plenty of mashups are already using the API including the 15+ mashups listed here.

The recent update adds this fun and useful capability as you can see in the docs. You can embed static maps that you can color by country or by US state. Here are a few simple examples of such maps, starting with a world map:

http://chart.apis.google.com/chart?cht=t&chs=440×220&chd=s:_&chtm=world

You’ll note that the parameters in the URL control the map, three of which are mandatory for any Google chart:

• type (cht): t represents the map type
• size (chs): The size used in the example (440 by 220 pixels) is the maximum available for all maps.
• data for the map (chd): Here s:_ is the simple encoding for “missing” (or no) value.
• and a fourth parameter particular to maps (chtm) indicates a geographic area (e.g., world, asia, middle_east).

Compare the world map to the “Hello World” of Google Charts to see how the same API can be used to simple pie chart (click on the pie chart to see the full url/call):

Going back to the world map, see how changing the chtm parameter in the URL displays a map of Europe and using three additional parameters (chco, chld, and chd) highlight Hungary in green, while keeping other European countries an off-white:

Are people already using the Google Chart API to make maps? Take a look at the article Making maps with Google Chart API (listed in the ProgrammableWeb mashup database), which discusses the issues involved with generating the following fuller example of a world map:

Jeffrey Barke wrote a short tutorial for creating maps with the Google Chart API.

As others have noted, the maps one can create in this way are more demonstrations of what’s possible than fully developed functionality — so it’ll be interesting to see whether/how Google refines this feature of the Google Chart API.

For more on the Google Chart API at ProgrammableWeb check-out Google Chart Mashups: Love and Stats.