[R] help wanted using R in a classroom

[Prof Brian Ripley]

On Tue, 18 Jan 2005, Liaw, Andy wrote:

>> From: bogdan romocea
>>
>> It appears you wouldn't get much improvement at all even if
>> the 2nd CPU
>> were used at 100%. Five R sessions can easily overwhelm one CPU. I
>> think you need (a lot) more CPUs than 2 to solve your problem.
>>
>> Possible solutions:
>> 1. Install R on each eMac. Since you have 40 of them, you
>> might want to
>> put together a script to do this.
>> 2. Get some boxes that can run Windows. On Windows, you can run R from
>> a CD/zip drive/USB drive. (So you could burn 40 CDs and have everyone
>> run their R session on their box.) As far as I know the same is not
>> true for GNU/Linux and Mac OS.
>
> If one can run Linux off a (live) CD, why wouldn't it be possible to do the
> same for R?  (Burn a Quantian DVD and you can boot a x86 box from it to run
> R.)
>
> If I'm not mistaken, it shouldn't be a problem running R off a USB pen drive
> or CD under Linux.  I can give it a shot tonight (if I can find the time).

There is.  The script `R' used to run R contains the absolute path to the 
R_HOME_DIR, e.g.

R_HOME_DIR=/usr/local/lib/R
if test -n "${R_HOME}" && \
    test "${R_HOME}" != "${R_HOME_DIR}"; then
   echo "WARNING: ignoring environment value of R_HOME"
fi
R_HOME="${R_HOME_DIR}"
export R_HOME

and so you would have to mount a removable drive on the exact place it was 
written for.  I am not sure that is possible with multiple USB ports.

I believe R's MacOS X port is written to be always in one place in the 
file system, and that is encoded by e.g.

     RLAPACK_LDFLAGS="-install_name \$(Rexeclibdir)/libRlapack.dylib"


-- 
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