[GRASS-user] r.mapcalc question

[Marco Lechner - FOSSGIS e.V.]

Hi Achim,

the neighborhood modifier doesn't seem to accept functions (you also
could try rand(), ...)

Marco

Achim Kisseler schrieb:
> Hello grass-users,
>
> I have a problem running a r.mapcalc procedure:
>
> given two maps
> dir_x,
> dir_y
>
> with 0,1,-1 entries
>
> I want to run:
>
> r.mapcalc "the_map=if(isnull(the_map),the_map[dir_x,dir_y],null())"
>
> in order to make a r.water.outlet on many many areas at the same time.
>
> The error I get is:
> syntax error, unexpected NAME, expecting INTEGER or '-'
>
> why does dir_x/dir_y does not return an integer here? Using int(dir_x)
> also does not work.
>
> Until now I use a r.mapcalc command with many "if", checking the
> direction of every pixel every time. But this is quite slow.
>
> Achim
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