[GRASS-user] v.to.rast in a python loop, error

[Moritz Lennert]

On 13/02/12 15:19, Johannes Radinger wrote:
>
>
> -------- Original-Nachricht --------
>> Datum: Mon, 13 Feb 2012 13:18:58 +0100
>> Von: Moritz Lennert<mlennert at club.worldonline.be>
>> An: Johannes Radinger<JRadinger at gmx.at>
>> CC: grass-user at lists.osgeo.org, glynn at gclements.plus.com
>> Betreff: Re: [GRASS-user] v.to.rast in a python loop, error
>
>> On 13/02/12 12:26, Johannes Radinger wrote:
>>>
>>>
>>> -------- Original-Nachricht --------
>>>> Datum: Mon, 13 Feb 2012 11:46:21 +0100 Von: Moritz
>>>> Lennert<mlennert at club.worldonline.be>  An: Johannes
>>>> Radinger<JRadinger at gmx.at>  CC: grass-user at lists.osgeo.org,
>>>> glynn at gclements.plus.com Betreff: Re: [GRASS-user] v.to.rast in a
>>>> python loop, error
>>>
>>>> On 13/02/12 11:32, Johannes Radinger wrote:
>>>>> And my output with although all maps were removed manually with
>>>>> g.remove
>>>> and cross checked:
>>>>>
>>>>> Launching script '/Users/Johannes Radinger/Desktop/test2.py'...
>>>>> (Mon Feb 13 11:12:27 2012) /Users/Johannes
>>>>> Radinger/Desktop/test2.py
>>>>> ---------------------------------------------- raster files
>>>>> available in mapset<PERMANENT>: basins          elevation_shade
>>>>> lakes           soils elevation       geology         landuse
>>>>> raster files available in mapset<user1>: rast_FULL_HYDRO
>>>>> rast_LENGTH
>>>> ^^^^^^^^^^^^^^^ ^^^^^^^^^^^
>>>>
>>>> Both maps _do_ exist in mapset user1. So it is normal that the
>>>> error appears.
>>>
>>> That is the strange behavior I am describing: Although g.list is
>>> first in the script, v.to.rast is processed first (at least
>>> partly)...or something like that...
>>
>> Sounds weird to me. You could try to suspend execution after each line
>> using time.sleep(secs).
>>
>> Note that in the last version of the script you posted the line with
>> g.remove is commented out.
>
> Hi again...
>
> I know, g.remove was commented out. If not everything is working. My interpretation is: the new raster maps are created first (before anything else is performed) then g.remove removes these and thereafter v.to.rast is processed...
>
> This is also supported when i try your suggestion (with time.sleep). Here what I run (and please look at the order of the output)? Is there anything running in parallel?
>
> #!/usr/bin/env python
>
> import sys
> import time
>
> import grass.script as grass
> import grass.script.setup as gsetup
>
> def main():
>
> 	print "start"
> 	sys.stdout.flush()
>
> 	grass.run_command("g.list",
> 					type = "rast")
>
> 	time.sleep(5)
> 	print "1st g.list over"
> 	sys.stdout.flush()
>
> 	grass.run_command("g.list",
> 					type = "rast")
>
> 	time.sleep(5)
> 	print "2nd g.list over"
> 	sys.stdout.flush()
>
> 	for i in ['FULL_HYDRO','LENGTH']:
>
> 		grass.run_command("v.to.rast",
> 					input = "streams at PERMANENT",
> 					output = "rast_"+i,
> 					type = "line",
> 					use = "attr",
> 					column = i)
>
> 	time.sleep(5)
>
> 	return 0
>
> if __name__ == "__main__":
> 	sys.exit(main())
>
>
> Output:
>
> Launching script '/Users/Johannes Radinger/Desktop/test2.py'...
> (Mon Feb 13 15:08:07 2012)
> /Users/Johannes Radinger/Desktop/test2.py
> start
> ----------------------------------------------
> raster files available in mapset<PERMANENT>:
> basins          elevation_shade lakes           soils
> elevation       geology         landuse
> raster files available in mapset<user1>:
> rast_FULL_HYDRO rast_LENGTH
> ----------------------------------------------
> 1st g.list over
> ----------------------------------------------
> raster files available in mapset<PERMANENT>:
> basins          elevation_shade lakes           soils
> elevation       geology         landuse
> raster files available in mapset<user1>:
> rast_FULL_HYDRO rast_LENGTH
> ----------------------------------------------
> ERROR: option<output>:<rast_FULL_HYDRO>  exists.
> ERROR: option<output>:<rast_LENGTH>  exists.
> 2nd g.list over
> (Mon Feb 13 15:08:23 2012) Command finished (15 sec)
>
>
> Looks weird as "2nd g.list over" is printed after the ERROR, resp.
> the ERROR is produced by v.to.rast before the print statement is processed...
>
> I launch the script from within GRASS6.5SVN (Mac OSX) from File ->  launch script.

Ok, I can reproduce your error using File->Launch script. No idea where 
that comes from, I'll try to look into it.

For the time being, just use g.remove or launch your script in the terminal.

Moritz