Every time I use pch=21 for plotting in R with lattice, my plot plots normally in the R plotting window and in pdf (circles with borders); however when I open a saved pdf version of my plot in Adobe Illustrator or Inkscape, the dots are oddly converted to "q"'s. Can anyone explain this? It's pretty frustrating, as I would like to edit my plot in either Illustrator or Inkscape.
I think you might want to use:
useDingbats = FALSE
as in:
pdf("myplot.pdf", useDingbats=FALSE)
plot()
dev.off()