[GRASS-user] mapcalc NULL issue

[Carlos "Guâno" Grohmann]

OK, i did with:

test=if(A==0|||isnull(A), B,A)

instead of

test=if(A==0|||isnull(A), B,A)

Note the "III" operator


Carlos



On 6/8/06, Wolfgang <wollez at gmx.net> wrote:
> out of the manual from r.mapcalc
>
> Example: The users wants the NULL-valued cells to be treated like zeros.
> To add maps A and B (where B contains NULLs) to get a map C the user can
> use a construction like:
>
> C=A + if(isnull(B),0,B)
>
> Cheers
> Wolfgang
>
> Carlos "Guâno" Grohmann schrieb:
> > Hello all.
> >
> > I have two rasters (SRTM_V2), one has data on the continental area,
> > with zero values in the ocean. The other (SRTM_30 PLUS) has values for
> > all region. I'd like to patch them, using r.mapcalc, like this:
> > if srtmv2==0 OR srtmv2==NULL, then use value from srtm30plus, else srtmv2.
> >
> > I tried this in mapcalc:
> >
> > test=if(A==0||isnull(A), B,A)
> >
> > but it didn't work. the result was the same as test=if(A==0, B,A).
> >
> > So how can I manage to get the condition for zero and null at the same
> > time? I mean, I can do this in a single operation, right? Or do I need
> > to make two operations?
> >
> > cheers
> >
>
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-- 
+-----------------------------------------------------------+
              Carlos Henrique Grohmann - Guano
  Geologist M.Sc  - Doctorate Student at IGc-USP - Brazil
Linux User #89721  - carlos dot grohmann at gmail dot com
+-----------------------------------------------------------+
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