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 versio
?pdf
has:
On some systems the default plotting character ‘pch = 1’ is
displayed in some PDF viewers incorrectly as a ‘"q"’ character.
(These seem to be viewers based on the ‘poppler’ PDF rendering
library). This may be due to incorrect or incomplete mapping of
font names to those used by the system. Adding the following
lines to ‘~/.fonts.conf’ or ‘/etc/fonts/local.conf’ may circumvent
this problem.
ZapfDingbats
Dingbats
Some further workarounds for problems with symbol fonts on viewers
using ‘fontconfig’ are given in the ‘Cairo Fonts’ section of the
help for ‘X11’.
That fontconfig declaration has worked for me in the past (and still does) on my Linux boxes. I suggest you set that or read the other pages indicated in the last of the quoted sentences and see if those fix the problem you are seeing.