[GRASS5] Re: [GRASSLIST:3328] Re: r.stats

[Markus Neteler]

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