[R] How to use alpha transparency channel for colors?

[kwright@eskimo.com]

Brian Ripley wrote:

> As so often happens, the `something wrong' is not reading the help file.
> As the NEWS file _also_ says
>
>     o	A 'version' argument has been added to pdf() device.  If this is
> 	set to "1.4", the device will support transparent colours.
>
> pdf("alpha.pdf", version="1.4")  should work for you: it does for me.

Thanks.  I did actually spend quite a bit of time searching around before
posting to R-help (always do as a matter of courtesy) but was unlucky in
that I grep'ed for 'alpha' and not 'transparent'.  Obvious mistake in
retrospect.

Kevin Wright