[GRASSLIST:169] Re: Sum for an area

[Daniel Victoria]

Thanks Markus! Silly me! MASK and r.sum does it.

Just for the record, I tested the sum with an FCELL map and a CELL and
the results differ by 600 mm (from 3208360.204620 to 3207755). This is
on a basin of 1311 cells (0.25 degrees resolution).

Once again, Thanks

Daniel

On 3/16/06, Markus Neteler <neteler at itc.it> wrote:
> On Thu, Mar 16, 2006 at 10:37:49AM -0300, Daniel Victoria wrote:
> > Hi all,
> >
> > This is probably a very dumb question but I'm stuck... I need to
> > calculate the total precipitation over a basin. I have the annual
> > precip raster and the basin raster. So, I'm issuing the command
> >
> > r.statistics base=sto_ica cover=ppt.81 at cru method=sum output=test
> >
> > And I get:
> > ERROR: This module currently only works for integer (CELL) maps
> >
>
> yes, an annoying problem...
>
> > Of course I could easily convert the precip map (ppt.81) to integer
> > but I'm afraid that, since it's a big area, this could result in some
> > errors (sub-estimation in the final sum).
> >
> > I'm sure there is another way to accomplish what I want, I just don't
> > know how. Or, should I not worry about errors (sub-estimations)?
> >
>
> if you set a MASK for the basin, will
> r.sum
> do the job?
>
> Markus
>
>
>