Hi all, I'm working on a dataframe (webs) with two variables ($size, $vspe), and two grouping factors ($type, $mutu). I would like to do a lattice plot wherein the levels of $mutu would be different shapes, and the levels of $type different colors. Additionally, I'd like to add a regression line for the two levels od $mutu only (no matter what the value of $type is). It's super easy to do in ggplot2 : ggplot(webs,aes(y=vspe,x=size)) + geom_point(aes(shape=mutu,colour=type)) + geom_smooth(aes(group=mutu,linetype=mutu),method='lm',fill=NA) However, I'm have no idea about how to do it in lattice. Does someone have any advice? Thanks -- View this message in context: http://r.789695.n4.nabble.com/lattice-group-by-two-factors-tp3561201p3561201.html Sent from the R help mailing list archive at Nabble.com.