Gordon Keith wrote:
> > Particular problems I am having:
> > > r.statistics base=facies cover=gabo20_slope method=average
> >
> > out=avg_slope
> > Sorry, <z> is not a valid flag
>
> this problem was fixed recently (2002-03-04), the
> next (!) CVS snapshot
> http://grass.itc.it/grass5/source/snapshot_release/
> will contain the fix (or you get it from CVS directly).
I've got the snapshot and r.statistics now runs, but does not seem to
produce meaningful results for method=average,min,max or sum,
[snip]
r.statistics method=mode,median,avedev,stddev,variance,skewness, or
kurtosis seem to give meaningful results for some data sets, but not
for others. So I'm not happy about trusting any results.
In particular where the raster is an aspect map generated by
r.slope.aspect the statistics for all classes seems to be identical.
Should I abandon r.statistics?
r.statistics doesn't work with floating-point maps at present. If you
convert the map to integer[1], you should get meaningful results.
[1] e.g. with "r.mapcalc 'out=int(in * 1000)'"
Ultimately, r.statistics needs a re-think with regard to handling
floating-point data.
--
Glynn Clements <glynn.clements@virgin.net>
On Tue, Mar 12, 2002 at 04:53:49AM +0000, Glynn Clements wrote:
Gordon Keith wrote:
> > > Particular problems I am having:
> > > > r.statistics base=facies cover=gabo20_slope method=average
> > >
> > > out=avg_slope
> > > Sorry, <z> is not a valid flag
> >
> > this problem was fixed recently (2002-03-04), the
> > next (!) CVS snapshot
> > http://grass.itc.it/grass5/source/snapshot_release/
> > will contain the fix (or you get it from CVS directly).
>
> I've got the snapshot and r.statistics now runs, but does not seem to
> produce meaningful results for method=average,min,max or sum,
[snip]
> r.statistics method=mode,median,avedev,stddev,variance,skewness, or
> kurtosis seem to give meaningful results for some data sets, but not
> for others. So I'm not happy about trusting any results.
>
> In particular where the raster is an aspect map generated by
> r.slope.aspect the statistics for all classes seems to be identical.
>
> Should I abandon r.statistics?
r.statistics doesn't work with floating-point maps at present.
[...]
To avoid further confusion, I have added a FP test: In case the cover
map is FP, the module writes an error and exists.
Ultimately, r.statistics needs a re-think with regard to handling
floating-point data.
Yes...
Markus