[GRASS-dev] New r3.stats version

[Sören Gebbert]

Hi folks,
i have implemented a new version of r3.stats.
This version uses a tree based search algorithm to
calculate the range table. This approach is much faster
then the linear range search i had implemented bevor.
Now the complexity should be O(n log(n)) and not O(n^2).

The limit of 100000 range table entries is now obsolet
and was removed. :)

Futhermore i have replaced the heapsort code with the GPL implementation 
used in r3.univar.

The latest code is available here:
http://www-pool.math.tu-berlin.de/~soeren/grass/modules/r3.stats.tar.bz2

I have compared the results of r3.stats which r.stats. And as i said 
befor, there is a ugly bug in the range table calculation of r.stats
which im not able to solve. Does anybody know if this bug is also 
present in the kergis code?
AFAICT r3.stats calculates the right results.

The next step will be a replacement of the equal value group search
algorithm, which needs to read the whole raster3d map into the memory.
I think using a linked list would be much faster and less memory consuming.

Any suggestions are welcome!

Best regards
Soeren