May be this work for rectangular image. require(rimage) img<-read.jpeg("file.jpg") image(rgb2grey(img)) nsamples<-1000 coordinates<-NULL for (i in 1:nsamples) { coordinates<-rbind( coordinates, cbind(x=as.integer(nrow(img)*runif(1)), y=as.integer(ncol(img)*runif(1)))) } But I sugest you give a look at "adehabitat" and "rimage" packages. Best, Miltinho
ronggui <[EMAIL PROTECTED]> escreveu: I have a map of a district (which is JPG format), and I want to do a sptial sampling based on the map. So is there any function to do spatial sampling of this type? Thanks! -- Ronggui Huang Department of Sociology Fudan University, Shanghai, China »ÆÈÙ¹ó ¸´µ©´óѧÉç»áѧϵ ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. --------------------------------- [[alternative HTML version deleted]]
______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.