[GRASS-user] Using a variable inside GRASS commands with Python code/ grass.mapcalc

[Brian Sanjeewa Rupasinghe]

Hi,

Many thanks. It worked for me. Then i have a similar problem in
GRASS.mapcalc. What i need next is to add viewshed of each observer
location cumulatively while looping through the observer locations in order
to have final integrated viewshed analysis map. So i used the following
command in Python (some code ommitted)

for i in:
    grass.run_command('r.viewshed', input = rinput, output = 'viewshed',
coordinate = [x,y], obs_elev = oelv, tgt_elev = th, memory = 4098, flags =
'b', overwrite = True, quiet = True)

    grass.mapcalc("viewshed_cum = viewshed + viewshed_cum", overwrite =
True, quiet = True)

It seems that expressions like sum = c + sum does not work inside
grass.mapcalc.Is there any alternative or other way around to get this
done? I am using GRASS 7 in Windows 7.

Cheers, Brian

On Tue, Jan 8, 2013 at 1:25 PM, Anna Kratochvílová <kratochanna at gmail.com>wrote:

> Hi Brian,
>
> On Tue, Jan 8, 2013 at 6:51 AM, Brian Sanjeewa Rupasinghe
> <jinkabs at gmail.com> wrote:
> > Hi all
> >
> > I am generating viewshed of each observer location by iterating through a
> > set of observer coordinate file through
> > Python code in Windows 7 . Below is the python command used in grass for
> > each iteration. According to this, each time
> > loop iterates, output is overwritten with the same name. Now what i need
> is
> > to keep each output of all the observer locations. For this, i need to
> > concatanate output name (i.e. 'viewshed' with loop index i which will be
> > 'viewshed' + str(i) ). How is that possible within
> > this grass.run_command?
> >
>
> just set a variable within each loop and use it in the run_command:
> for i in ... :
>     out =  'viewshed' + str(i)
>     grass.run_command('r.viewshed', input = rinput, output = out, ...)
>
>
> Regards,
> Anna
>
> > grass.run_command('r.viewshed', input = rinput, output = 'viewshed',
> > coordinate = [x,y], obs_elev = oelv, tgt_elev = th, memory = 4098, flags
> =
> > 'b', overwrite = True, quiet = True)
> >
> > Cheers, Brian
> >
> > _______________________________________________
> > grass-user mailing list
> > grass-user at lists.osgeo.org
> > http://lists.osgeo.org/mailman/listinfo/grass-user
> >
>
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