[R] running R from PHP

[Prof Brian Ripley]

On Tue, 3 Feb 2004, Philippe Glaziou wrote:

> @biology.nmsu.edu <brook at biology.nmsu.edu> wrote:
> > I would like to construct a PHP script that runs R to generate a
> > graphics file.  Running R itself is no problem.  However, it seems
> > impossible to instantiate one of the graphics devices to create
> > output.  For example, the "normal" bitmap devices (e.g., jpeg, png,
> > etc.) are derived from X11, which requires a display.  This seems
> > true, even if no output is ever directed to a real display.  

It _is_ documented on the help page, and output _is_ directed to a real 
display: you just mever see it.  It is possible make use a virtual display 
such as that provided by Xvfb.

> > For some reason, the postscript device seems to suffer from similar
> > problems.
> > 
> > Is there a trick to creating a graphics device in the absence of an
> > actual display in order to create an image in a file?
> 
> 
> If you need a bitmap graphic file, I would suggest the use of
> ImageMagick:

You may as well use the bitmap() device built into R, which is also a 
wrapper for the use of ghostscript.  That too is described on the help 
page.

I have never seen a reported problem with getting postscript output from a
script. After reading the posting guide, please give us some useful
details of what happened.

> cunegonde:~/tmp> ls
> foo
> 
> cunegonde:~/tmp> cat foo
> pdf(file="g.pdf")
> plot(1:5)
> dev.off()
> 
> cunegonde:~/tmp> R --no-save <foo>/dev/null && convert g.pdf g.png
> 
> cunegonde:~/tmp> ls -g
> -rw-------    1 glaziou      3374 2004-02-03 11:58 g.pdf
> -rw-------    1 glaziou      4115 2004-02-03 11:58 g.png
> -rw-------    1 glaziou        80 2004-02-03 11:58 foo
> 
> 
> This works from a unix console without X running (the postcript
> device works similarly on my machine). R can easily be fed this
> way with a file and parameters passed from a php script.
> 
> 

-- 
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