Area cartograms
On Mon, 27 Feb 2006, Miha Staut wrote:
Dear listers, Does anybody know if any command is implemented in R for creating cartograms where the area of the polygon reflects the size of the variable in question. E.g. in a map of the countries of the world (projection should be equivalent of course), the area of the country would indicate the size of the population of the country, not the actual area. I would be happy with either contiguous polygons with distortion of the shape or non contiguous polygons without shape distortion.
http://www.okada.jp.org/RWiki/index.php?Rmap%A4%F2%BB%C8%A4%C3%A4%BF%C3%CF%BF%DE%C9%BD%BC%A8 towards the bottom of the page is about what is known at the moment, it scales the polygon coordinates towards the centroid (assuming in the example that each data row is a single polygon). Has anyone any more ideas or code? The example is nice, and could be generalised for SpatialPolygons objects quite easily (because they have centroids and areas pre-calculated. Roger
Thanks, Miha
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Roger Bivand Economic Geography Section, Department of Economics, Norwegian School of Economics and Business Administration, Helleveien 30, N-5045 Bergen, Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43 e-mail: Roger.Bivand at nhh.no