mfrow(n)
Utility Functions for Graphics
mfrow returns a 2-long numeric vector suitable to
use in par(mfrow=x), that will arrange
n panels in a single plot.
mfrow(1)[1] 1 1mfrow(2)[1] 1 2mfrow(3)[1] 2 2mfrow(4)[1] 2 2mfrow(10)[1] 3 3