[GRASS-dev] adding lib_arraystats

[Dylan Beaudette]

On Monday 11 February 2008, Moritz Lennert wrote:
> Hello,
>
> I've finally gotten around to continue working on the d.thematic.*
> modules, and more specifically on the classification code. As mentioned
> earlier, I think it makes sense to make the latter into a library, so I
> decided to create lib_arraystats which contains functions for collecting
> basic statistics and for finding class breaks in arrays of doubles. In
> the future this could be filled with more statistical functions on such
> arrays.
>
> Could the gurus please have a look and tell me if the attached files are
> decent enough (except for the lacking documentation) to be committed to
> svn for further development ? Once that's done, I can also commit the
> d.thematic.area and v.class modules.
>
> Moritz

Nice work Moritz.

On this thread-- it would be neat if we can use (along side Moritz's and 
existinf stat libs) the shared R library, when available. I think that it 
would have to be a compile-time option, and the user would have to have R 
installed, and compiled with the '--enable-R-shlib' flag. This would allow us 
to switch between the default, basic set of algorithms, and the entire suite 
of R codes. Some of these functions might not work with huge datasets (R 
works with data in-memory)-- but it would allow us to program more 
complicated algorithms without re-inventing them.

This thread reminded me of doing this, as sometimes it is useful to look 
for "natural classes" within data. Instead of re-implementing a variation of 
K-means, we could just pass an array to the appropriate (set of) R functions.


However, an hour spent tinkering around with the R shared lib examples left me 
mostly frustrated....


-- 
Dylan Beaudette
Soil Resource Laboratory
http://casoilresource.lawr.ucdavis.edu/
University of California at Davis
530.754.7341