V.

If you want to give two plot commands, and do not want the second one to wipe out the first one, do the following.

plot(first plot)

par(new=TRUE)

plot(second plot)

This will superimpose the second plot on the first. Note that the two plots may have different scales. To ensure that they use a particular (say, same) [...]

John Fox’s package, “car”, has a very useful scatterplot.matrix (or simply spm) to make scatterplots of pairs from a set of variables. The plot below was created using

library(“car”)
scatterplot.matrix(~Exppop+Exppphc+literacy+Oppphc, reg.line=lm, smooth=TRUE, span=0.5, diagonal = ‘density’, data=temp)
dev.print(jpeg, file=”~/graph-matrix.jpg”, width=500, [...]