Given a region divided into polygons, how can I find which polygons have any edges that are not neighbouring other polygons?
For example, if the region is Africa and the polygons are countries, I want to find the land-locked and non-landlocked countries. My first idea is to create a large rectangle bigger than Africa, and cutout from it the country polygons, leaving me with a rectangle with an Africa-shaped hole. Then I test each country again to see if it shares a border with the hole. If it does, its not land-locked. I can probably do all this with rgeos, but if I've missed a simpler way I'd like to hear it... Obviously I fear sliver polygons after my previous geometry manipulation fun.... Barry _______________________________________________ R-sig-Geo mailing list [email protected] https://stat.ethz.ch/mailman/listinfo/r-sig-geo
