[GRASS-dev] r.mapcal and python

[Roberto Antolí­n]

Hi all, Moritz,

Moritz Lennert escribió:
>> grass.run_command('r.mapcalc', expression = "%s=%s-%s" % (out, dsm, dtm))
> 
> The expression= parameter only exists in GRASS7, but not in grass6.x.
> 
> So, r.mapcalc expression=k=1
> 
> will give you
> 
> in GRASS6.x: a map called 'expression' with the value 1

That was exactly what I obtained: a map called 'expression' with the 
difference between dtm and dsm.

>> grass.run_command('r.mapcalc', %s = "%s-%s" % (out, dsm, dtm))
> 
> No expert, but shouldn't this be:
> 
> grass.run_command('r.mapcalc', "%s = %s-%s" % (out, dsm, dtm))

In fact that was the first thing I tried, but I got this error:

syntax error, unexpected '-', expecting NAME or STRING
Parse error

Regards,
Roberto.