On Sat, Oct 10, 2009 at 5:51 PM, Peter Ehlers <ehl...@ucalgary.ca> wrote: > The key will show the levels of the 'groups' factor. So you will > have to ensure that the factor fed to groups has the levels > that you want displayed. ?xyplot explicitly states that > drop.unused.levels will NOT do that for you. > > (Didn't Deepayan just answer something like this?)
Yes: https://stat.ethz.ch/pipermail/r-help/2009-October/214516.html and the Lattice book has a longer discussion (in particular section 9.2.5). -Deepayan > -Peter Ehlers > > Jacob Wegelin wrote: >> >> The following code produces a legend ("key") that mentions the unused >> levels of Block. >> >> library(MEMSS) >> xyplot(yield~nitro, subset=(Block=="I" | Block=="II"), data=Oats, >> group=Block, auto.key=T) >> >> and adding "drop.unused.levels=T" does not fix it. And in fact even >> the following does not solve the problem: >> >> xyplot(yield~nitro, data=Oats[Oats$Block=="I" | Oats$Block=="II",], >> group=Block, auto.key=T) >> >> The following workaround solves it, but seems inelegant: >> >> junk<-Oats[Oats$Block=="I" | Oats$Block=="II",] >> junk$Block<-factor(as.character(junk$Block)) >> xyplot(yield~nitro, group=Block, data=junk, auto.key=T) >> >> What is the elegant or "proper R thinking" way to do this? That is, I >> want to get a key that only mentions the levels of Block that are used >> in the plot. >> >> Thanks >> >> Jacob A. Wegelin >> Assistant Professor >> Department of Biostatistics >> Virginia Commonwealth University >> 730 East Broad Street Room 3006 >> P. O. Box 980032 >> Richmond VA 23298-0032 >> U.S.A. >> E-mail: jwege...@vcu.edu >> URL: http://www.people.vcu.edu/~jwegelin ______________________________________________ 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.