I don't think this is possible. With an opaque background you can get back
the background color just by overwriting, but any additional painting can only
increase the opacity so you can't get back to transparent.
-thomas
On Thu, 8 Apr 2010, Terry Therneau wrote:
I have a case where the easiest way to draw a particular symbol would be
to draw something a little bigger, and then use polygon(... , col=0) to
erase the extra stuff. Just how to do this best when par('bg') =
'transparent' is, however, eluding me. I've looked through the archives
and the book R Graphics without quite seeing the light.
Help or pointers to help would be welcome.
Terry T
Details (for the inquiring mind). In drawing a pedigree subjects are
depicted as cirle, square, diamond, or triangle (for gender= male,
female, unknown, terminated). This can be subdivided into shaded
regions to show the value of various ancillary variables. One ancillary
is easy - just fill with a color. For two you fill the left and right
half separately, etc. Two, three, four, ... variables become special
cases for each symbol. An easy solution is to draw a larger circle with
the requisite number of shaded slices, then erase away what we don't
want.
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
Thomas Lumley Assoc. Professor, Biostatistics
tlum...@u.washington.edu University of Washington, Seattle
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
