Visualizing Spatial Relationships - Data Points: Visualization That Means Something - page 288

Finally, if your data is qualitative with classes or categories, then you
might want a unique color for each (Figure 8-14).
FIGurE 8-14 Qualitative color scheme with ColorBrewer
When you have your color scheme, you have two more things to do. The
first is to decide how the colors you picked match up to the data range, and
the second is to assign colors to each region based on your choice. You can
do both with Python and Scalable Vector Graphics (SVG) in the following
examples.
MAP CouNTIES
The U.S. Bureau of Labor Statistics provides county-level unemployment
data every month. You can download the most recent rates or go back
several years from its site. However, the data browser it provides is kind of
outdated and roundabout, so for the sake of simplicity (and in case the BLS
site changes), you can download the data at http://book.flowingdata.com/
ch08/regions/unemployment-aug2010.txt . There are six columns. The first is a
code specific to the Bureau of Labor Statistics. The next two together are
a unique id specifying county. The fourth and fifth columns are the county
name and month the rate is an estimate of, respectively. The last column