I'm not sure exactly where to point my finger with this one, but there is a nasty surprise to the unsuspecting user. There is no check on the length of the vector passed in the pch= argument to plot, it is just recycled as necessary: plot(1:10,1:10,pch=1:2) gives alternating circles and triangles. The nasty bits come up especially with plot.formula: x<-1:10;y<-1:10 plot(y~x,subset=x%%2==1,pch=x%%2) - and the plotting symbols are *not* all the same. Even more pernicious, if missing values are involved:
y[x%%2==1]<-NA plot(y~x,pch=x%%2)
gives you the wrong symbols (in practice, this messes up things like plot(height~age,pch=sex) rather badly!). It would help to get a warning that the lengths don't match, but are there any good uses of the recycling of pch?
O__ ---- Peter Dalgaard Blegdamsvej 3 c/ /'_ --- Dept. of Biostatistics 2200 Cph. N (*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918 ~~~~~~~~~~ - (p.dalgaard@biostat.ku.dk) FAX: (+45) 35327907 -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-devel mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-devel-request@stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._