That's an easy one with ggplot2. library(ggplot2) dataset <- data.frame(variable = gl(2, 50, labels = c("x", "z")), value = c(runif(50), rnorm(50))) ggplot(data = dataset, aes(x = value, fill = variable)) + geom_histogram(position = "dodge") + scale_fill_manual(values = c("red", "blue"), guide = "tile")
But I don't prefer to put two histograms into the same graphs. Making a seperate histogram for each variable makes is easier to compare them. Or you could use a density plot. ggplot(data = dataset, aes(x = value, fill = variable)) + geom_histogram() + facet_grid(variable ~ .) + scale_fill_manual(values = c("red", "blue"), guide = "tile") ggplot(data = dataset, aes(x = value, colour = variable)) + geom_density() + scale_colour_manual(values = c("red", "blue"), guide = "line") HTH, Thierry ------------------------------------------------------------------------ ---- ir. Thierry Onkelinx Instituut voor natuur- en bosonderzoek / Research Institute for Nature and Forest Cel biometrie, methodologie en kwaliteitszorg / Section biometrics, methodology and quality assurance Gaverstraat 4 9500 Geraardsbergen Belgium tel. + 32 54/436 185 [EMAIL PROTECTED] www.inbo.be Do not put your faith in what statistics say until you have carefully considered what they do not say. ~William W. Watt A statistical analysis, properly conducted, is a delicate dissection of uncertainties, a surgery of suppositions. ~M.J.Moroney -----Oorspronkelijk bericht----- Van: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Namens Juan Pablo Fededa Verzonden: donderdag 24 januari 2008 15:44 Aan: r-help Onderwerp: [R] two histograms in the same graph Dear Contributors: I have two vectors x and z, and I want to display the histograms of both vectors in the same graph, x in red bars, z in blue bars. If you have any clue on how to do that, I will be very glad to hear it!!!!!! Thanks in advance again, Juan Pablo Fededa [[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.