Hello, Apologies for the newbie question. I have x,y data that I want to plot - I currently have a third column which identifies the run. X, Y, RunNum currenly I have xyplot(X,Y,data=xyplotdata, groups=RunNum) but there is such alot of data -- what I want is another grouping that say would plot xy data RunNum 1-9 in Panel1, RunNum 10-19 in Panel2 , RunNum 20-29 in Panel3 etc, Any help appreciated. - I have tried variants of equal.count and subsets - without success. Thanks,