Dear all I am experiencing a strange problem when using the focalFilter function in the raster package.
Whilst checking some code, I tried it on a toy dataset (p267) and a simple function. I have a set of filters in a list (w.ij). These can be found at http://dl.dropbox.com/u/15122401/Rproblem/toyexample.zip or http://dl.dropbox.com/u/15122401/Rproblem/toyexample.Rdata p267 is a 16x16 matrix. The filters are all 15x15 binary filters. I take the filter and move it around the matrix (4 centre points (8,8), (8,9), (9,8), (9,9)). At each of these points I multiply the filter by the underlying values in p267. I then sum the new matrix, as follows sum(w.ij[[2]] * p267[-16,-16]) sum(w.ij[[2]] * p267[-16,-1]) sum(w.ij[[2]] * p267[-1,-16]) sum(w.ij[[2]] * p267[-1,-1]) I can repeat this for the other filters in the w.ij list. I then try to do this using raster (eventualy I want to apply such functions to a raster image not a small matrix), so I try: p267.r <- raster(p267) for(i in 1:5){ tmp <- focalFilter(p267.r, filter=w.ij[[i]], fun=sum) print(tmp@data@values[which(tmp@data@values != "NA")]) } As you can see, the values obtained from the focalFilter function do not match my test. I cannot see why this should be. Can anybody help? Nick --- > sessionInfo() R version 2.12.2 (2011-02-25) Platform: i386-pc-mingw32/i386 (32-bit) locale: [1] LC_COLLATE=English_United Kingdom.1252 LC_CTYPE=English_United Kingdom.1252 [3] LC_MONETARY=English_United Kingdom.1252 LC_NUMERIC=C [5] LC_TIME=English_United Kingdom.1252 attached base packages: [1] stats graphics grDevices utils datasets methods base other attached packages: [1] raster_1.8-3 sp_0.9-79 loaded via a namespace (and not attached): [1] grid_2.12.2 lattice_0.19-17 tools_2.12.2 > ---- _______________________________________________ R-sig-Geo mailing list [email protected] https://stat.ethz.ch/mailman/listinfo/r-sig-geo
