It works. However, now I get another odd result: in some plots there are straight lines connecting the end of a line with the beginning of another one.
On Wednesday 04 February 2004 04:03, Umberto Maggiore wrote:
Using data from a multicenter study with a parallel-group design comparing two treatments, I plotted each subject's time change of X after stratifying for center: xyplot(X ~ time | center, type="l", panel=panel.superpose, groups=subject) Now I want these lines to take different colours according to the variable "treatment". Any help?
Umm, you should already have lines colored differently by different 'subject's. Do you want to further differentiate by treatment ? If that's so, there's probably no good way. You could try creating a new factor combining subject and treatment and use that as the groups argument, e.g., factor(paste(as.character(subject), as.character(treatment), sep = "/")) Deepayan