Hi Sébastien, Not sure about an elegant, general way but here is something quick and dirty:
p <- barplot(matrix(1:8, 2)) axis(1, at = p, labels = letters[1:4]) axis(1, at = c(mean(p[1:2]), mean(p[3:4])), labels = paste("\n", LETTERS[1:2]), padj = 1) Cheers, Josh On Mon, Aug 22, 2011 at 10:14 AM, Sébastien Vigneau <sebastien.vign...@gmail.com> wrote: > Hi, > > I would like to draw a stacked bar chart with four bars (say "a", "b", "c", > "d") . Two bars belong to group A and the two others to group B. Therefore, > I would like to have, on the x-axis, a label for each bar and an additional > label for each group, positioned underneath. To give an idea, the x-axis > labels should look like this: > |a|b|c|d| > | A | B | > > Do you know how I can generate such two-levels labels in R? > > Thank you for your help! > > Sebastien > > [[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. > -- Joshua Wiley Ph.D. Student, Health Psychology Programmer Analyst II, ATS Statistical Consulting Group University of California, Los Angeles https://joshuawiley.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.