Thank you David, the bwplot option does what I need: x11(height=8,width=11) bwplot ( mortality~ attend|type, pch=95,cex=5,col=2, par.settings=list( box.rectangle = list(col = "transparent"), box.umbrella = list(col = "transparent"), plot.symbol = list(col = "transparent") ), panel=function(x,y,...){ panel.grid(lty=5) panel.xyplot(x,y,pch=16,jitter.x=TRUE,col=1) panel.bwplot(x,y,...) }, data = x,aspect=2:1,layout=c(3,1))
However, I am interested in also learning how to do it in xyplot as well. I wasn’t able to follow the last two set of instructions (condition on packet.number and loop over segments), wondering if I can ask for your help for the correct code (my attempt resulted in all three mean lines within each panel): x11(height=8,width=11) xyplot ( mortality ~ attend|type, panel=function(x,y) { panel.grid(lty=5) panel.xyplot(x,y,pch=16,jitter.x=TRUE,col=1) for(i in 1:3) { panel.segments(x0=c(0.7, 1.7), x1=c(1.3, 2.3), y0=c(tapply(x$mortality[x$type==i], x$attend[x$type==i], median)), y1=c(tapply(x$mortality[x$type==i], x$attend[x$type==i], median)),col="red",lwd=4) } }, data = x,aspect=2:1,layout=c(3,1)) thank you again. I also found your info on data.frame useful. -- View this message in context: http://r.789695.n4.nabble.com/Drawing-a-line-in-xyplot-tp4538689p4540389.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ 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.