Dear list, The stratified random sampling problem that I submitted a few days ago has already been solved, with the help of several of you, notably Edzer Pebesma. Edzer came up with the following solution: library(sp) library(rgdal) nc1 <- readShapePoly(system.file("shapes/sids.shp",package="maptools")[1], proj4string=CRS("+proj=longlat +datum=NAD27")) pts = do.call(rbind, sapply(slot(nc1, "polygons"), spsample, n=1, type="random")) plot(nc1) points(pts, col='blue', pch=19, cex=1) As it happened, the do.call statement did not work in my case (Edzer and Roger may look into why it does not work with all shapes) and had to be replaced by: for (i in 1:length(slot(nc1, "polygons"))) { pt = spsample(nc1[i,], n=1, type="random") if (i == 1) pts = pt else pts = rbind(pts, pt) }
I am so happy! Gerard _______________________________________________ R-sig-Geo mailing list R-sig-Geo@stat.math.ethz.ch https://stat.ethz.ch/mailman/listinfo/r-sig-geo