[GRASS-user] Again on raster statistics

[Luigi Ponti]

Dear list,

I take up again a question I posted a couple of week ago with no aswer. 
Maybe I am missing something trivial. If so, I would ask you to please 
let me know.

In order to simulate a strange behaviour I ususally get when analyzing a 
raster obtained via v.surf.idw, I have imported the following 
sample_raster (into a  Lambert Conformal Conic location with roughly the 
extent of Italy) :

north: 1957791.56244761
south: 764918.56244761
east: 754857.88911685
west: -279947.29662612
rows: 10
cols: 10
1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 7 8 9 10

using the following command:

GRASS 6.1.cvs (EurLCC):~ > r.in.ascii -f input=sample_raster.txt 
output=sample_raster title="This is a sample raster"

Then if I use r.stats with 9 steps I get:

GRASS 6.1.cvs (EurLCC):~ > r.stats -nap sample_raster nsteps=9
r.stats:  100%
1-2 246878233266.702148  22.23%
2-3 122842792398.404068  11.06%
3-4 124035440868.291550  11.17%
4-5 122842792398.404068  11.06%
5-6 124035440868.291550  11.17%
6-7 122842792398.404068  11.06%
7-8 124035440868.291550  11.17%
8-9 122842792398.404068  11.06%
9-10 124035440868.291550  11.17%

But with 2 steps I get:

GRASS 6.1.cvs (EurLCC):~ > r.stats -nap sample_raster nsteps=2
r.stats:  100%
1-5.5 1110355725439.734619 100.00%
5.5-10 124035440868.291550  11.17%

Which does not make a lot of sense to me: there is too much area in the 
first half and too little in the second half.
Any hints appreciated. Regards,

Luigi