[R] Changing style for groups in xyplot

[Antje Steller]

Hello,
I have a (hopefully) quick question concerning the xyplot function.

The xyplot works very fine for me - I am using it to display functions
of two variates depending on several other factors. I am therefor also
using the groups argument, so that the symbols in each panel appear in
different colors.

Now I would like to change how the different groups are displayed - now
they are circles in different colors, and I would like to change those
colors.

Can you tell me how to do this?

my complete xyplot command right now looks like this:

xyplot(a ~ b| t*h, groups=r, xlab="Zyklen", ylab="Riss [%]",
auto.key=list(lab=levels(r),columns=3))

Thank you very much,
Antje