(This article was first published on Ecological Modelling... » R, and kindly contributed to R-bloggers)
With ggplot2 there is a possibility to create divide bars of a histogram into different categories:
library(ggplot2)
dd <- data.frame(measure=runif(100), cat=sample(c("a","b","c"), 100, replace=T))
qplot(measure, data=dd, fill=cat, binwidth=0.2)
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