There is a paper called "Density-equalizing map projections: Diffusion-based algorithm and applications" by Michael T. Gastner and M. E. J. Newman, which explains their algorithm (which is based in diffusion equations) for generating value-by-area cartograms.

While it explains the theoretical side of the mathematics involved with their algorithm, it doesn't explain how they actually implemented it. I tried to piece it together by looking at the source code from cart, but I don't have the programming knowledge (it's written in c, which I don't know) required to understand it.

If anyone has at least a decent understanding of it and can explain the steps needed to create a cartogram using their algorithm, that would be greatly appreciated. Otherwise, if you have other helpful resources on the topic, those would be good too.

  • $\begingroup$ In the paper, what is the equation to be solved? $\endgroup$ – davidhigh May 9 '17 at 18:23
  • $\begingroup$ For density-based diffusion, you are trying to solve for the velocity given the diffusion equation, and then integrate the velocity field to solve for the cumulative displacement of each point over a time interval. $\endgroup$ – Frick Steves May 9 '17 at 18:47

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