[R] PNG diver problem

[Prof Brian Ripley]

On Wed, 28 Nov 2001 apjaworski at mmm.com wrote:

>
> I got a couple of answers already indicating that this is a known
> "problem".  Thanks to everyone who responded and apologies for reposting a
> known problem.  I must have missed the last post about this - I searched
> the mailing list archive and found it about a year ago.  Apparently, one of
> the solutions is to use the bitmap driver which produces the PNG files by
> default anyway.
>
> I noticed that the png help page mentions that it depends on the x11
> device.  It just was not clear to me that one cannot use x11 in batch mode.

Well, that's not true, which is why it is not on the help page.  You can't
use it in BATCH mode, because X11 is set explicitly off.  I can use it in
batch mode: Debian Linux users cannot.

>From R-devel:

     R can be compiled without support for either or both of these
     devices: this will be reported if you attempt to use them on a
     system where they are not supported.  They will not be available
     if R has been started with `--gui=none' (and will give a different
     error message), and they may not be usable unless the X11 display
     is available to the owner of the R process.

See Also:

     `bitmap' provides an alternative way to generate PNG and JPEG
     plots that does not depend on accessing the X11 display but does
     depend on having GhostScript installed.

> Finally, I am still curious why this thing works under Windows.  Was the
> png driver rewritten for it?  Does it still depend on the windows device
> but it can be invoked in batch mode?

Same reason it works under batch modes on Solaris: the screen device is
available to write with.


-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
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 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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