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2006 Mar 21
1
Getting polygons from contiguous grid cells having same value in sp
I have been using the sp package to deal with gridded data. I would like to know how to extract the vertices (x,y) of polygons that outline areas of like-valued cells in a grid. Here is a simple 3x3 grid: 2 2 1 1 2 1 1 1 3 x <- c(1,1,1,2,2,2,3,3,3) # define a 3 x 3 array of points y <- c(1,2,3,1,2,3,1,2,3) h <- SpatialPoints(cbind(x,y)) # make these an sp object of the points