Creating very small plots (2.5 cm wide) in Sweave

Hi everyone,

I was wondering if anyone has any code they could share for creating
thumbnail plots in Sweave.  For example, I'd like a plot like the
following:

y <- c(40, 46, 39, 44, 23, 36, 70, 39, 30, 73, 53, 74)
x <- c(6, 4, 3, 6, 1, 5, 6, 2, 1, 8, 4, 6)
opar <- par(mar=c(3,3,0,0))
plot(x, y, xlab="", ylab="")
abline(h=mean(y), col="red")
par(opar)

to come out about 2.5 cm wide.

Thanks for any assistance,

Andrew

Andrew Robinson
Senior Lecturer in Statistics                       Tel: +61-3-8344-9763
Department of Mathematics and Statistics            Fax: +61-3-8344-4599
University of Melbourne, VIC 3010 Australia
Email: a.robinson at ms.unimelb.edu.au    Website: http://www.ms.unimelb.edu.au