[R] Limiting size of pairs plots

[Sébastien]

Dear R-users,

I would like to add a legend at the bottom of pairs plots (it's my first 
use of this function). With the plot function, I usually add some 
additional space at the bottom when I define the size of the graphical 
device (using mar); grid functions then allows me to draw my legend as I 
want.
Unfortunatley, this technique does not seem to work with the pairs 
function as the generated plots use all the available space on the 
device (see below). I guess I am missing a key argument... my attempts 
to modify the oma, mar, usr arguments were unsuccesfull, and I could not 
find any helpful threads on the archives.

As usual, any advice would be greatly appreciated

Sebastien


pdf(file="C:/test.pdf", width=6, height= 6 + 0.2*6)

par(mar=c(5 + 6,4,4,2)+0.1)

pairs(iris[1:4], main = "Anderson's Iris Data -- 3 species", pch = 21, 
bg = c("red", "green3", "blue")[unclass(iris$Species)])

dev.off()