[R] problem with X11 when talking via PHP web interface

From: Paul Hammer <paul.hammer_at_tfh-wildau.de>
Date: Fri, 16 May 2008 15:10:31 +0200


hi members,

At the moment i try to create a web-based GUI for R. I am at the beginning of this project but i have already now a strange problem.

I would like to create an image which should also be saved. i realize this with following code line in my PHP file:

$output= intval(shell_exec("R --no-save --slave < test.R 1>../tmp/R.output 2>../tmp/R.log"));

The code in the R script (test.R) is:

jpeg(filename = "plot.jpeg", width = 1024, height = 768, units = "px", pointsize = 12, quality = 75, bg = "white") split.screen(c(2,1));
screen(1,new=TRUE)
plot(s);
screen(2,new=TRUE)
plot(y);
dev.off()

The error message which I get is this one:

Error in jpeg(filename = "plot.jpeg", width = 1024, height = 768, units = "px", : X11 module cannot be loaded In addition: Warning message: In jpeg(filename = "plot.jpeg", width = 1024, height = 768, units = "px", : unable to load shared library '/home/combiuser/emeyer/R/R-2.7.0/modules//R_X11.so': /usr/lib/libcairo.so.2: undefined symbol: FT_GlyphSlot_Embolden Execution halted

And the strange thing is when i type in the shell just "R --no-save --slave < test.R 1>../tmp/R.output 2>../tmp/R.log" the image is created and all works fine!!!! It has to be a problem for the X11 module when i start R via Apache/PHP. But why and what could I do to solve this problem???

Any suggestions would be really helpful.

Best regards from Germany
Paul

sessionInfo()
R version 2.7.0 (2008-04-22)
i686-pc-linux-gnu

locale:
LC_CTYPE=en_US.UTF-8;LC_NUMERIC=C;LC_TIME=en_US.UTF-8;LC_COLLATE=en_US.UTF-8;LC_MONETARY=C;LC_MESSAGES=en_US.UTF-8;LC_PAPER=en_US.UTF-8;LC_NAME=C;LC_ADDRESS=C;LC_TELEPHONE=C;LC_MEASUREMENT=en_US.UTF-8;LC_IDENTIFICATION=C

attached base packages:
[1] stats graphics grDevices utils datasets methods base

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