[GRASS-user] Variables in r.mapcalc other than raster?

GRASS GRASS user
1

Hello,

I have to perform some complex calculations on several hundreds of maps using a shell script. A set of variables would ease the task, therefore my question: Is there any possibility to use a set of predefined variables (no maps!) in r.mapcalc? - It seems to me as if it is always looking for maps and consequently states "i is not a map".

Is there any way to do this?

Thanks,

Roland

2

On 22/01/08 12:07, Roland Pape wrote:

Hello,

I have to perform some complex calculations on several hundreds of maps using a shell script. A set of variables would ease the task, therefore my question: Is there any possibility to use a set of predefined variables (no maps!) in r.mapcalc? - It seems to me as if it is always looking for maps and consequently states "i is not a map".

Is there any way to do this?

Have you checked http://grass.itc.it/gdp/raster/mapcalc-algebra.pdf ? There is a section on temporary variables, but I'm not sure if these aren't also "map" variables.

Moritz

3

Hello Moritz,

unfortunately, the temporary variables there also seem to be "map" variables...

Moritz Lennert wrote:

On 22/01/08 12:07, Roland Pape wrote:

Hello,

I have to perform some complex calculations on several hundreds of maps using a shell script. A set of variables would ease the task, therefore my question: Is there any possibility to use a set of predefined variables (no maps!) in r.mapcalc? - It seems to me as if it is always looking for maps and consequently states "i is not a map".

Is there any way to do this?

Have you checked http://grass.itc.it/gdp/raster/mapcalc-algebra.pdf ? There is a section on temporary variables, but I'm not sure if these aren't also "map" variables.

Moritz

4

Roland Pape wrote:

I have to perform some complex calculations on several hundreds of maps
using a shell script. A set of variables would ease the task, therefore
my question: Is there any possibility to use a set of predefined
variables (no maps!) in r.mapcalc? - It seems to me as if it is always
looking for maps and consequently states "i is not a map".

Where does r.mapcalc get the expression from? If it's passed as a
command-line argument, the shell will perform variable substitution
within a double-quoted string. The shell will also perform
substitution within here documents.

If the expression is being read from a file, you'll need to arrange
for the substitutions to be performed using e.g. sed.

--
Glynn Clements <glynn@gclements.plus.com>

5

Hi,
thanks to all for help!
As recommended in the manual, I put single quotes around my expressions and got "invalid map" for any "no-map" variables. Using double quotes instead solved the problem. - Sometimes it is rather simple...

Best regards,

Roland