repeating steps in GRASS r.mapcalc

Question

I simply cannot find out the following: I want to repeat a calculation in GRASS GIS several times. Is there a command for r.mapcalc to repeat a calculation x times (similar to this possibility in r.mfilter, for example)....besides listing that step x times in s shell scripts (I use shell).

Answer 1

You can call r.mapcalc in for loop. In shell it could look like this:

X=5
# initialize first map
r.mapcalc "old = 10"

# loop
for I in `seq $X` 
do
  r.mapcalc "new = old + 10" --overwrite
  g.rename rast=new,old --overwrite
done

In shell command seq 5 creates a sequence 1, 2, 3, 4 , 5.

Note that you shouldn't use r.mapcalc like this (read from and write in the same map):

r.mapcalc "old = old + 10" --overwrite