[R] 2D look up (within interval)

YasirKaheil yasir.kaheil at ec.gc.ca
Thu Apr 29 19:58:21 CEST 2010


Hi,
I have a matrix of X and Y coordinates, and one pair of coordinates that I
need to know it corresponds (or is closest) to which row in the matrix. For
example:
MC<- cbind(rep(1:1000,each=1000),rep(1:1000,1000));
p<-c(543.1,440.05);

I know that if you do which.min you'll get the answer, which will be row #
542440, but which.min is slow and this process needs to be repeated a lot. 
I tried using match and findInterval and %in% but I don't know how I can use
them to find in 2 columns simultanuously.

Please help!
Thanks!

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