[R] Trellis dotplot label keys

[Omar Baqueiro]

Hello,

I am trying to plot a chart similar to the typical barley yield dotplot:
dotplot(variety ~ yield | site, data = barley,
        groups = year, auto.key = list(space = "right"),
        xlab = "Barley Yield (bushels/acre) ",
        aspect=0.5, layout = c(1,5))

However, I need the plot have different shapes for the different keys
and currently I just get circles with different colours as the keys.
Can someone tell me the way to indicate R how to assign automatically
keys which are black/white printer friendly?

Thank you!

Omar.

-- 
Omar Baqueiro Espinosa
Computer Science PhD Candidate
Computer Systems Engineer
Workpage: www.csc.liv.ac.uk/~omar/
HomePage (spanish):http://www.baqueiro.co.uk/
PGP Key available at: www.csc.liv.ac.uk/~omar/pgp.html
_____