Sunday, November 07, 2004

Color schemes

One of the side discussions around the purple map was: what is a proper color scheme to color such a map, beyond just a red-blue-purple mode. Many ideas were suggested, and some of them are reflected on the page, but till a commenter mentioned it, I didn't realize that cartographers have studied this problem in great depth.

Cindy Brewer, a cartographer at Penn State, has designed a beautiful web site that helps with coloring choropleths (the technical term for maps where each region is colored with a single color). You decide what kind of data you have and how many categories of colors you needs, and the flash applet generates a color scheme, as well as color values in a variety of color maps (RGB/CMYK/etc).

Using a bivariate 10-value divergent color scheme (color spreads out from the middle of the data range), here is the Election 2004 cartogram:

For more maps, visit my new cartogram page.

1 comment:

  1. I'd wondered what red-white-blue would look like; thank you. The Brewer colorization is georgeous.

    Part of the problem with the map's not looking correct is that the cartogram by voter is as wrong in its way as the county by area map. The shapes need to be drawn with a mulitplier for each voter in each state that reflects the electoral vote of the state to compensate for the different electoral college value of a vote in each state; "voters" in Wyoming are much bigger (have more influence) than those in California.

    A fascinating topic.

    htom (htom nospam 4722 of aol period com)


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