plot(0, 0, pch=21, bg="#FF000022", col="#FF000001") may be (close to) what you are looking for.
On Tue, 22 Apr 2008, Karl Ove Hufthammer wrote: > R version 2.7.0 RC (2008-04-20 r45403) > > When using semi-transparent filled plotting symbols, the border of the > symbol has a different (darker) colour than the interior: > > plot(0, 0, pch=19, col="#FF000022") > > (Saving this as a PDF and looking at it magnified may make it easier to > see.) > > This is pretty annoying, since when plotting partially overlapping > points, the border colour dominates, making the colour of overlapping > points more saturated than they should be. > > This isn't so much of a problem when using very large values of 'cex', > since the width of the border is constant, and doesn't vary with cex. > But with small values (and the default value) of cex, it's very visible. > > I thought this maybe could be solved by using pch=21 instead of pch=19, > and setting the 'bg' colour to the same colour as 'col', like this. > > plot(0, 0, pch=21, col="#FF000022", bg="#FF000022") > > But this has no effect. 'bg' *does* set the background (interior) colour > (this is easy to check by using a different colour), but not the border > colour, which is determined by 'col' alone. > > So I guess in theory I can get the border and interior the same colour by > setting 'col' to a ligher colour than the one I actually want to use, > and then set the 'bg' colour to the one I want to use. But how should I > select the lighter colour so that the darker version (i.e., the border > colour) is the one I want? > > Frankly, the current behaviour feels much more like a bug than a feature. > If I set pch=19, I want a completely filled circle, even if my chosen > colour is partially transparent. > > I'm using > R version 2.7.0 RC (2008-04-20 r45403) > i686-pc-linux-gnu > > -- > Karl Ove Hufthammer > > ______________________________________________ > 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. > -- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595 ______________________________________________ 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.