update: Here’s the dorling.py code, which is just a port of Danny Dorling’s C to Python. Remember, this only works with a particular topological input format (see county.in). I’ve done some more experiments with the circular cartogram algorithm: here, here, and most recently here.
Dr. Daniel Dorling was recently nice enough to provide me with some C sourcecode for producing his circular cartograms. And it works great! I’ve already ported it to Python and have consumed the result in Flash. Below is a screenshot of a circular cartogram of British population by county. That’s after 300 iterations of the algorithm, which took about 2 seconds.
Next step: getting the program to consume shapefiles/DBFs rather than its current proprietary format. This will work its way into something. Stay tuned!
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[...] talked about this before: Parts I & [...]
[...] Part 2 of what will now be an ongoing series about my work with the Dorling circular cartogram algorithm; see part 1 [...]
[...] with many other gems of quantitative geography). Dr. Dorling made Pascal and C code available. I ported it to Python, and began experimenting, mostly in vain, on a method that worked with a shapefile as input, but [...]
[...] addition to knowing the neighbors of all features, Daniel Dorling’s original algorithm requires as input the shared border lengths of all contiguous features. These are used in the [...]