Integrating the Derivative

What was I doing yesterday and why did I need a drawing program (I used Gimp by the way)? Look to the left! The image graphically shows the election results (governor only, I do have the data for other races though) for Berrien County on the city and township level. A darker shade of red or blue indicates a greater proportion of Republican or Democrat votes respectively.

I got the idea from Robert Vanderbei’s website. He has the same type of images for the entire US on the county level. I first saw his images spreading on the internet after the 2004 election and I thought it was a neat idea. So I decided to do it on a city/township level for my own county.

This is my first attempt so I could use some feedback. The red and blue shades I picked were fairly arbitrary. I took the extreme edge of the red side of the color map which had a value (hue?) of 360. A value of 260 gave a nice shade of purple and going back a further 100 points to 160 gave a bright shade of blue. I then took the margin over 50% of whichever party happened to win (e.g. if the party won by 56%, I’d take 6), multiplied it by two, and added the result to the midpoint of 260. As an example, that bright spot of blue on the map is the city of Benton Harbor. 93% of the votes were for the Democrats. I got the color I needed by taking (93-50) * 2 and subtracting the result (86) from 260, giving a color value of 174. If anyone has any better ideas on how to do this let me know.

I also put together some spreadsheets for the counties I’m working on. So far I have Newaygo County finished and I’m about halfway done with Berrien County. I’ll upload both of those when I finish with Berrien County. I got the election data for Berrien County from their website and for Newaygo County from Election Magic.

I’m already thinking about creating an image showing turnout too. If you think of something that might be interesting to map out in an image let me know in the comments.

*Update*  I think I figured out the best way to do the colors.  You take the percentage that each party got (grouping third parties into one) and then multiply that by 255 (the max amount in adjusting RGB values) and then put the results into whatever custom color program you’re using.  For example, say Granholm (blue) got 46%, DeVos (red) 50%, and third parties (green) 4%.  Multiplying each percentage by 255 you the following values for Red, Blue, and Green: 128, 117, 10.