Thanks for suggestions on plotting different symbols in an xyplot by Sarkar and Wiener in answer to my question:
"I have a four panel xyplot. I wish to plot each point as an open or filled circle depending on the value of an indicator variable." Wiener: You don't even need to tell it to use panel.superpose -- using "groups" tells it (try it with & without and see!). The pch values are set by group (here, value of ind2). It might be more elegant to use trellis.par.set to set the pch values, but I'm lazy. (It seems to have the desired effect -- try subsetting on ind2, and you get a subset of the values.) Hope this helps, Sarkar: Not directly. You do need to change the plotting character (pch). Here are two ways to do it (the second is longer but recommended): dotplot(variety ~ yield | site, data = barley, groups = year, pch = c (1, 16)) dotplot(variety ~ yield | site, data = barley, groups = year, auto.key = TRUE, par.settings = list(superpose.symbol = list(pch = c(1, 16)))) A related question: My xyplot is essentially a time series (up-and-down experimental design). Thus I need to connect the points sequentially regardless of the group value. With the groups argument, type = 'b' gives two lines - one for each group. Any more suggestions? Thanks, Nathan ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html