Re: [R] running JPEG device on R 1.9.1 using xvfb-run on Linux

From: Tim Churches <tchur_at_optusnet.com.au>
Date: Thu 13 Oct 2005 - 17:56:36 EST

Prof Brian Ripley wrote:
> On Wed, 12 Oct 2005, David Zhao wrote:
>
>

>>Does anybody have experience in running jpeg device using xvfb-run on
>>linux? I've been having sporadic problem with: /usr/X11/bin/xvfb-run
>>/usr/bin/R --no-save < Rinput.txt, with error saying: error in X11
>>connection. Especially when I run it from a perl script.

>
>
> Not sure what `xvfb-run on Linux' is, as it is not on my Linux (FC3).
> If you Google it you will find a number of problems reported on Debian
> lists. Here I would suspect timing.
>
> What I do is to run Xvfb on screen 5 by
>
> Xvfb :5 &
> setenv DISPLAY :5
>
> and do not have a problem with the jpeg() or png() devices. I do have a
> problem with the rgl() package, but then I often do on-screen (on both 32-
> and even more so 64-bit FC3).

For R-embedded-in-Python (via RPy) on a Web server, we have been using a Python programme to automatically start Xvfb if it is not already running. You can find a copy of the programme in the NetEpi-Analysis tarball available at
http://sourceforge.net/project/showfiles.php?group_id=123700

The tricky bit is managing the permissions for the Xvfb session, particularly in a Web server context - you need to take care. However, this use of Xvfb has been perfectly reliable (on Red Hat Enterprise Linux 2.1 and 3 with R2.0 and R 2.1)
>

>>Is there a better way of doing this? or how can I fix the problem.

>
> You really should update your R.

Yes. We now use GDD, which is an alternative R graphics driver for raster graphics (Jpeg and PNG), available via CRAN. It allows R to directly generate jpeg and png files on a Linux or Unix machine without the need for an X server to be running (not even Xvfb). The quality of the output is also better than the standard R X11/png/jpeg graphics device due to the use of anti-aliased fonts by GDD. Earlier versions of GDD were a bit buggy, but so far we have found the latest version (0.1.7) to be fine. It is a bit fiddly to install all the libraries it requires as well as the recommended (no-cost) Microsoft TrueType fonts, but the effort is worth it. Many thanks to Simon Urbanek for his work on GDD. Tim C



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