I don't know enough to assess whether I have a misunderstanding or a mistake.
spsample() with type='random' is giving an error, but succeeding with type='stratified'. Maybe random sampling requires projection information and stratified doesn't? I may have constructed my SpatialPolygonsDataFrame incorrectly? Thanks -Don Details: spgd consists of two rectangles, one inside the other, and the inside one is a hole. The outer one has vertices in counter-clockwise order; the inner one in clockwise order. > class(tst) [1] "SpatialPolygonsDataFrame" attr(,"package") [1] "sp" > summary(tst) Object of class SpatialPolygonsDataFrame Coordinates: min max r1 990396.8 990762.3 r2 213369.4 213702.6 Is projected: NA proj4string : [NA] Data attributes: ID zone:1 > stst <- spsample(tst,type='stratified',n=50) > plot(tst) > points(stst) > stst <- spsample(tst,type='random',n=50) Error in `proj4string<-`(`*tmp*`, value = <S4 object of class "CRS">) : proj4string only works for class(es extending) Spatial ########## > sessionInfo() R version 2.5.0 (2007-04-23) powerpc-apple-darwin8.9.1 locale: C attached base packages: [1] "stats" "graphics" "grDevices" "utils" "datasets" "methods" "base" other attached packages: maptools sp foreign rmacq "0.6-12" "0.9-14" "0.8-20" "1.0" ########## ## since tst is fairly small, here it is: ########## > tst An object of class "SpatialPolygonsDataFrame" Slot "data": ID zone zone Slot "polygons": [[1]] An object of class "Polygons" Slot "Polygons": $zn An object of class "Polygon" Slot "labpt": [1] 990579.4 213536.2 Slot "area": [1] 64601.13 Slot "hole": [1] FALSE Slot "ringDir": [1] 1 Slot "coords": x y [1,] 990499.3 213702.6 [2,] 990762.3 213559.8 [3,] 990658.2 213369.4 [4,] 990396.8 213513.2 [5,] 990499.3 213702.6 $zn2 An object of class "Polygon" Slot "labpt": [1] 990584.4 213537.3 Slot "area": [1] 30367.20 Slot "hole": [1] TRUE Slot "ringDir": [1] -1 Slot "coords": x y [1,] 990492.6 213650.8 [2,] 990441.8 213549.4 [3,] 990673.3 213423.7 [4,] 990728.1 213525.6 [5,] 990492.6 213650.8 Slot "plotOrder": [1] 1 2 Slot "labpt": [1] 990579.4 213536.2 Slot "ID": [1] "zone" Slot "area": [1] 94968.33 Slot "plotOrder": [1] 1 Slot "bbox": min max r1 990396.8 990762.3 r2 213369.4 213702.6 Slot "proj4string": CRS arguments: NA -- -------------------------------------- Don MacQueen Environmental Protection Department Lawrence Livermore National Laboratory Livermore, CA, USA _______________________________________________ R-sig-Geo mailing list R-sig-Geo@stat.math.ethz.ch https://stat.ethz.ch/mailman/listinfo/r-sig-geo