[GRASS-user] r.mapcal sintax error

GRASS GRASS user
1

Hi all,

i'm in trouble using r.mapcalc in Grass 6.5 svn

In order to replace in a raster map (basin_10m) the values 24,26 with 28, i use the following cmd line:

r.mapcalc 'basin_10m_2=if(basin_10m==24),28'
r.mapcalc 'basin_10m_2=if(basin_10m==26),28'

the result is:

syntax error, unexpected ',', expecting $end
Parse error

which is the correct command to use?

Thank you in advance.

margherita

--
Ing. Margherita Di Leo
Ph.D. Student Methods and Technologies for Environmental Monitoring
Department of Environmental Engineering and Physics (DIFA)

University of Basilicata Campus Macchia Romana
85100 - Potenza Italy

Office: +39-0971205363
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2

On Sat, Apr 11, 2009 at 10:00 PM, Margherita Di Leo <diregola@gmail.com> wrote:

Hi all,

i'm in trouble using r.mapcalc in Grass 6.5 svn

In order to replace in a raster map (basin_10m) the values 24,26 with 28, i
use the following cmd line:

r.mapcalc 'basin_10m_2=if(basin_10m==24),28'
r.mapcalc 'basin_10m_2=if(basin_10m==26),28'

You need to set the braces correctly (personally, I use
double quotes to be able to use shell variables). Also
better define the "else" part:

     if(condition, then, else)

so

r.mapcalc "basin_10m_2=if(basin_10m==24, 28, null())"
r.mapcalc "basin_10m_3=if(basin_10m==26, 28, null())"

Note that I changed the second map name to _3 otherwise
it would overwrite the first.

You can also combine conditions, e.g.:
     if(condition1 && condition2, then, else)

cheers
Markus

3

On Sat, Apr 11, 2009 at 10:29 PM, Margherita Di Leo <diregola@gmail.com> wrote:

Markus Neteler wrote:

On Sat, Apr 11, 2009 at 10:00 PM, Margherita Di Leo <diregola@gmail.com>

...

r.mapcalc "basin_10m_2=if(basin_10m==24, 28, null())"
r.mapcalc "basin_10m_3=if(basin_10m==26, 28, null())"

the matter is that i don't want to replace the whole map with null value , i
only want to replace 24 and 26 with 28 and preserve the other values of the
map.

Sure, then (to preserve, use the map name):

r.mapcalc "basin_10m_2=if(basin_10m==24, 28, basin_10m)"
r.mapcalc "basin_10m_3=if(basin_10m_2==26, 28, basin_10m_2)"

or simply

r.mapcalc "basin_10m_2=if(basin_10m==24 || basin_10m==26, 28, basin_10m)"

Markus