Using jpeg() function over cgi

Fri, Jun 13, 2003 7:22 AM #

Hi

I have seen a few posts to this list regarding problems accessing the x11() device over cgi - namely, when trying to create a graphic using the jpeg() function, everything is fine from the command line but it won't work over cgi, producing the error:

"Unable to open connection to X11 display"

Has anyone actually solved this particular problem satisfactorily?

Please reply direct to me as I am not a member of the list (yet!)

Thanks in advance for your help

Michael Watson
Head of Informatics
Institute for Animal Health,
Compton Laboratory,
Compton,
Newbury,
Berkshire RG20 7NN
UK

Phone : +44 (0)1635 578411 ext. 2535
Mobile: +44 (0)7764 490236
E-mail: michael.watson at bbsrc.ac.uk

Brian Ripley

Fri, Jun 13, 2003 8:01 AM #

Yes, it has been solved and discussed in the R-help archives many times.
The help(jpeg) page is pretty explicit too.  One alternative is bitmap().

To use jpeg() under a Unix-alike you need to set up an X server that your
R process can use.  It's a bit hard to help you do that when you don't
even mention your OS (I am inferring it is a Unix-alike), but you may be
able to solve the permissions problem or you may be able to set by a
server by something like Xvfb.  In any case, it is not an R problem

On Fri, 13 Jun 2003, michael watson (IAH-C) wrote:

No, not the x11() device, but the jpeg() device.  They are not the same!

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 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595