Mix two scatterplots in R

Question

I would like to mix two scatterplots in just one, with different colours to each of them for comparasion.

codes used to obtains the two scatterplots:

 plot(allsize, allfreq)

 plot(allsize2, allfreq2)

Cheers!

Answer 1

plot(allsize, allfreq, col = "blue")
plot(allsize2, allfreq2, col = "red", add = TRUE)