Sengly wrote:
> Dear all,
> 
> I have a large collection of about 50 million xml files. I would like
> to do some basic statistic about the data. For instance, what is the
> average value of the tag <A>, discover the co-occurence of some values
> inside the data, etc
> 
> Do we have any automated if not not semi-automatic tools that allow us
> to define some rules to understand our data. Tools with visualizations
> would be the best.
> 
> Do you have any ideas?
> 
> Ps: I was suggested to look at SPSS. Anyone has some experience
> before?
> 
> Thanks,
> 
> Sengly

This looks like more of a problem in statistics than XML, so perhaps you 
are asking in the wrong place. But, ...

For an open-source statistics package, try R ( a derivative of S  ):
   http://www.r-project.org/

For R wrapped-up with many other mathematical tools (using python)
try Sage:
http://www.sagemath.org/index.html


<quote>

  Sage is a free open-source mathematics software system licensed under 
the GPL. It combines the power  of many existing open-source packages 
into a common Python-based interface.
Mission: Creating a viable free open source alternative to Magma, Maple, 
Mathematica and Matlab.

</quote>

Bye for now,
Ken.