I think I located the problem. the data frame associated with my spatial object (Insitu_sp) contains some NAs. And in this case, the function plot does not like NAs. It simply behaved strangely. The code below did the trick :
idx = is.na(Insitu[,"SPM"]) ptsize = 0.35*(sqrt(Insitu[!idx,"SPM"])+1) plot(Insitu_sp[!idx,"SPM"],col="red",pch=19,cex=ptsize) Does the symbols function supports spatial (sp) objects? I could not manage to make it work with my sp data. Quoting Greg Snow <greg.s...@imail.org>: > The symbols function may work better than plot for this situation. ______________________________________________ R-help@r-project.org 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.
