[R] Identify points that lie within polygon

[Jeff Newmiller]

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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Sent from my phone. Please excuse my brevity.

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
>
>
>
>
>--
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>
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