Hi: Here are a couple of attempts, one with base graphics and one with lattice.
d <- data.frame(TreatA = gl(2, 50, 100, labels = c('High', 'Low')), TreatB = rep(gl(2, 25, 50, labels = c('High', 'Low')), 2), Test = c(rnorm(50, 50, 10), rnorm(50, 100, 10))) lbl <- c('High\nHigh', 'High\nLow', 'Low\nHigh', 'Low\nLow') # Lattice version: library('lattice') bwplot(Test ~ interaction(TreatA, TreatB), data = d, scales = list(x = list(at = 1:4, label = lbl))) trellis.focus('toplevel') panel.text(0.08, 0.065, 'Treat A:\nTreat B:', cex = 0.75) trellis.unfocus() boxplot(Test ~ interaction(TreatA, TreatB), data = d, xaxt = 'n') axis(1, at = 1:4, lab = lbl) mtext('Treat A:\nTreat B:', side = 1, line = 1, at = 0) You can adjust the position and size of the text to your taste. The idea for the lattice plot comes from the following post in the list archives: http://r-project.markmail.org/search/?q=panel.text#query:panel.text+page:4+mid:2e3xpb2tsufntwya+state:results HTH, Dennis On Fri, Jul 29, 2011 at 4:53 AM, Tom Wilding <tom.wild...@sams.ac.uk> wrote: > Dear All > > I would like to produce interaction boxplots and this seems to work: > > par(mfrow=c(2,2)) > A=sample(rnorm(50,50,10)) > B=sample(rnorm(50,100,10)) > Test=merge(A,B,by=0)#by=0 where 0 is the row.names > TreatA=(gl(2,50,100,labels=c("High","Low"))) > TreatB=rep(gl(2,25,50,labels=c("High","Low")),2) > Newdata=data.frame(TreatA,TreatB,Test) > > bwplot(x~TreatA:TreatB,data=Newdata) > > However, I would prefer the X axis labels to be different, such that there > are two label rows (TreatA and TreatB) something like this: > > TreatA High High Low Low > TreatB High Low High Low > > any guidance on achieving this much appreciated. > > Regards > > Tom > > > [[alternative HTML version deleted]] > > ______________________________________________ > 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. > ______________________________________________ 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.