GRASS r.catchment causes r.reclass error

Question

I'm using GRASS 7.0.3 on Windows 7 (part of the QGIS 2.14 distribution) with the extra installed add-on module r.catchment. I'm trying to use GRASS to calculate a catchment raster, but I keep getting this error related to the use of the r.reclass module by r.catchment (see output below).

Here are the GRASS commands that I execute:

v.in.ogr input=location_utm.shp output=V_LOCATION_UTM --overwrite --quiet
r.in.gdal input=astgtm_utm.img output=R_ASTGTM_UTM --overwrite --quiet
r.catchment elevation=R_ASTGTM_UTM start_points=V_LOCATION_UTM buffer=R_CATCHMENT sigma=15 area=100000000 map_val=1 --verbose
r.out.gdal input=R_CATCHMENT output=catchment.img

This is the output (and error) I am getting:

C:\Temp>r.catchment elevation=R_ASTGTM_UTM start_points=V_LOCATION_UTM buffer=R_CATCHMENT sigma=15 area=100000000 map_val=1 --verbose
There is already a MASK in place, and you have also selected to mask slope
values above 15.
The high slope areas (slope mask) will be temporarily added to current
MASKED areas for the calcualtion of the catchment geometry.
The original MASK will be restored when the module finishes
Wanted buffer area=100000000
step 1 of 4: Calculating cost surface
Calculating for time costs only
Creating optional slope mask
 100%
Maximum cost distance value 58426 covers an area of 2243889760 square map
units
Commencing to find a catchment configuration.....
Catchment configuration found!
Cost cutoff 5671 produces a catchment of 100003308 square map units.
Creating output map
ERROR: Cannot open rules file <c:\users\xxx\appdata\local\temp\tmpeopqnp>
Traceback (most recent call last):
  File "C:\Users\xxx\AppData\Roaming\GRASS7\addons/scripts/r.catchment.py", line 379, in <module>
    main()
  File "C:\Users\xxx\AppData\Roaming\GRASS7\addons/scripts/r.catchment.py", line 329, in main
    output='cost.reclass.%s' % pid, rules=temp.name)
  File "C:\PROGRA~1\QGISES~1\apps\grass\grass-7.0.3\etc\python\grass\script\core.py", line 394, in run_command
    return handle_errors(returncode, returncode, args, kwargs)
  File "C:\PROGRA~1\QGISES~1\apps\grass\grass-7.0.3\etc\python\grass\script\core.py", line 312, in handle_errors
    returncode=returncode)
grass.exceptions.CalledModuleError: Module run None ['r.reclass', 'rules=c:\\users\\xxx\\appdata\\local\\temp\\tmpeopqnp', 'input=temporary.cost.9304', 'output=cost.reclass.9304'] ended with error
Process ended with non-zero return code 1. See errors in the (error) output.

I have no idea why this error occurs or how to solve this.

Answer 1

This script is a Python script: (r.catchment., r.catchment.py and in the error message r.catchment.py) The error is in lines 328-329 with rules=temp.name -> Cannot open rules file <c:\users\xxx\appdata\local\temp\tmpeopqnp>

grass.run_command('r.reclass', overwrite=grass.overwrite(), input=cost,
                output='cost.reclass.%s' % pid, rules=temp.name)

And I think it is a Windows problem because temp is defined with the standard Python module tempfile as a temporary file in the lines 325-330

#(import tempfile, line 130)
temp = tempfile.NamedTemporaryFile()
temp.write('0 thru %s = %s\n' % (int(cutoff),  mapval))
temp.flush()
grass.run_command('r.reclass', overwrite=grass.overwrite(), input=cost,
                output='cost.reclass.%s' % pid, rules=temp.name)
temp.close()

On my PC (Mac OS X, Unix), in the Python shell or in the Python console of GRASS GIS

import tempfile
temp = tempfile.NamedTemporaryFile()
tempfile.gettempdir()
'/var/folders/k9/7s3l5fvd5g1dy31b6sms18fr0000gn/T'
temp.name
'/var/folders/k9/7s3l5fvd5g1dy31b6sms18fr0000gn/T/tmpWcTD_A'

and the script find this file (in general C:\TEMP, C:\TMP, /tmp, /var/tmp, or /usr/tmp according to the PC, the OS and the environment variables)

In your case, the generated temp.name is c:\users\xxx\appdata\local\temp\tmpeopqnp but the script don't find it.

Therefore the question of BERA ? (GRASS GIS is not QGIS, nor GRASS GIS from QGIS, particularly with an add-on module)

Answer 2

To make this r.catchment.py script work on Windows, replace lines 325-330, being:

temp = tempfile.NamedTemporaryFile()
temp.write('0 thru %s = %s\n' % (int(cutoff),  mapval))
temp.flush()
grass.run_command('r.reclass', overwrite=grass.overwrite(), input=cost, output='cost.reclass.%s' % pid, rules=temp.name)
temp.close()

with these lines:

temp = tempfile.NamedTemporaryFile(delete=False)
temp.write('0 thru %s = %s\n' % (int(cutoff),  mapval))
temp.flush()
temp.close()
grass.run_command('r.reclass', overwrite=grass.overwrite(), input=cost, output='cost.reclass.%s' % pid, rules=temp.name)

Answer 3

I am the author of r.catchment.py, so this is a very enlightening thread. Indeed, I developed on Linux and was only able to test on MacOS, but not on Windows. I was not aware of this issue with temp files on Windows, but the final solution listed seems to make some sense. I will update the r.catchment.py script with a check for a Windows OS, in which case the alternative temp file construct will be used. It may take a little while before I can get around to it, but hopefully before the end of the year...

Thanks!

~Isaac