R: Density plot with colors by group?

Question

I have data from 2 populations. I\'d like to get the histogram and density plot of both on the same graphic. With one color for one population and another color for the other on

Answer 1

A base R solution could be:

  hist(AA, probability = T, col = rgb(1,0,0,0.5), border = rgb(1,0,0,1), 
       xlim=range(AA,BB), breaks= 50, ylim=c(0,0.025), main="AA and BB", xlab = "")
  hist(BB, probability = T, col = rgb(0,0,1,0.5), border = rgb(0,0,1,1), add=T)
  lines(density(AA))
  lines(density(BB), lty=2)

For alpha I used rgb. But there are more ways to get it in. See alpha() in the scales package for instance. I added also the breaks parameter for the plot of the AAs to increase the binwidth compared to the BB group.