Identify points that lie within polygon
This is off-topic (not about R), and a quick Web search of "test within polygon" yields many results, and adding "R" to the search when using Google provides hints about applying the algorithms in R.
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Ally <a.rushworth at stats.gla.ac.uk> wrote:
I have a complex 2D polygon with thousands of vertices, and I'd like to be able to identify points from a large set contained within the polygon, and was wondering if there might be an efficient way of doing this? Any advice would be useful! Here is a small example of what I mean: # make polygon v1<-c(0,1,1,2,1,3,6,7) v2<-c(1,3,3,5,6,7,8,9) plot(v1, v2, type = "n" ) polygon(v1, v2, lwd = 2, col = "red") # plot a set of candidate grid points grid<-seq(0, 10, length.out = 30) pts<-expand.grid(grid, grid) points(pts, pch = 19, col = 1, cex = 1) Many thanks! Alastair -- View this message in context: http://r.789695.n4.nabble.com/Identify-points-that-lie-within-polygon-tp4639289.html Sent from the R help mailing list archive at Nabble.com.
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