[GRASS-user] r.mapcalc question

Achim Kisseler ak7 at jupiter.uni-freiburg.de
Thu Jan 28 08:13:02 EST 2010

Hello grass-users,

I have a problem running a r.mapcalc procedure:

given two maps

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.


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