title: In R, how do I make a plot for only one group?
body: <p>What I want to do is to apply the plot function only to certain selection of records in a dataset. Let's say, I have a column of length (numeric), a column of body mass (numeric) and a column of sex (M or F) (of some animal). I want to scatterplot the length vs the mass, but only for M, so that F won't appear on the plot. How do I do that?</p>