Hello All, I posted this over on R-help, but was then directed here.
I've been pouring through the various spatial packages, but haven't come across the right thing yet. Given a set of points in 2-d space X, i'm trying to find the subset of points in Y proximate to each point in X. Furthermore, the proximity threshold of each point in X differs (X$threshold). I've constructed this myself already, but it's horrificly slow with a dataset of 40k+ points in one set, and a 700 in the other. A very inefficient example of what I'm looking for: X = data.frame(x=c(1,2,3), y=c(2,3,1), threshold=c(1,2,4)) Y = data.frame(x=c(5,2,3,4,2,5,2,3), y=c(5,2,2,4,1,2,3,1)) proximate=list() i=1 for (pt in 1:length(X$x)) { proximate[[i]] <- sqrt((X[pt,]$x - Y$x)2 + (X[pt,]$y - Y$y)2) > X[pt,]$threshold i=i+1 } proximate Perhaps crossdist() in spatstat is what I should use, and then code a comparison with X$threshold after the cross-distances are computed. However, I was wondering if there was another tool I should be considering. David Winsemius suggested I first compare on in each coordinate to cull points outside the threshold on that axis first, before computing distances, which will help. Any and all thoughts are very welcome. Thanks in advance. Thanks, Allie -- Alexander Shenkin PhD Candidate School of Natural Resources and Environment University of Florida http://snre.ufl.edu/people/students.asp _______________________________________________ R-sig-Geo mailing list R-sig-Geo@stat.math.ethz.ch https://stat.ethz.ch/mailman/listinfo/r-sig-geo