Another possibility might be to use a 2d kernel density estimate (eg. kde2d from library(MASS). Then for the high density areas plot the density contours, for the low density areas plot the individual points.
Hadley ______________________________________________ [EMAIL PROTECTED] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html