[Qgis-developer] help for processing algorithms

[Iacopo Borsi]

Hi,
I'm new to this list, so I don't know if this is the right place to post my issue.... Sorry for that.

However, my problem is about running processing algorithm directly from a python script.
I'm using QGis 2.8 under Windows 7, and python correctly installed under Qgis directory.

This is the problem: if I run a GRASS algorithm using the GUI, everything is ok.
The same algorithm, with the same source input file and applying the same parameters... it fails when called by processing through a (very simple!) Python script.

Now, after several tests, I'm also using the point shape file embedded under processing/test folder (just to be sure of integrity of input file).
If you see below, I'm also looking at processing.log, and what is surprising is that logs seem exactly the same !!!

I post below the short code I'm using and the log file I got.
Again, I remark that the algorithm run from GUI is perfectly working :-0

Any help or suggestion?

Thank you so much in advance.
Iacopo

My python code to run Inverse Distance Squared Weighting interpolator (GRASS).

---
from PyQt4.QtGui import *
from qgis.core import *
from qgis.gui import *
from PyQt4.QtCore import *
import processing

# Define the data source
vl = iface.activeLayer()
if vl.isValid() :
    print 'Layer is valid!'

# Extent
ext = vl.extent()
xmin = ext.xMinimum()
ymin = ext.yMinimum()
xmax = ext.xMaximum()
ymax = ext.yMaximum()

# Name of the field
myfield = 'PT_NUM_A'

# Run Grass alg
out_ras = processing.runalg("grass:v.surf.idw", vl , 12 ,2.0, myfield , False,   "%f , %f, %f, %f "% (xmin , xmax , ymin , ymax), 10.0, -1, 0.001, None)

# retrieve the raster output and load it in Qgis:
fileoutput= out_ras['output']
fileInfo = QFileInfo(fileoutput)
baseName = fileInfo.baseName()
rlayer = QgsRasterLayer(fileoutput, baseName)
if rlayer.isValid():
    QgsMapLayerRegistry.instance().addMapLayer( rlayer )
else:
     print 'Raster layer is not valid!'

****
Log info I got from processing.log
---
Using GUI:
---
ALGORITHM|Tue Jul 21 2015 14:39:01|processing.runalg("grass:v.surf.idw","C:\\Users\\iacopo.borsi\\.qgis2\\python\\plugins\\processing\\tests\\data\\points.shp",12,2,"PT_NUM_A",False,"270778.60198,270855.745301,4458921.97814,4458983.8488",10,-1,0.0001,None)
INFO|Tue Jul 21 2015 14:39:01|GRASS execution commands|g.proj -c proj4="+proj=utm +zone=30 +ellps=intl +towgs84=-87,-98,-121,0,0,0,0 +units=m +no_defs"|v.in.ogr min_area=0.0001 snap=-1 dsn="C:\Users\iacopo.borsi\.qgis2\python\plugins\processing\tests\data" layer=points output=tmp14374823414715 --overwrite -o|g.region n=4458983.8488 s=4458921.97814 e=270855.745301 w=270778.60198 res=10|v.surf.idw input=tmp14374823414715 npoints="12" power="2" column="PT_NUM_A" output=outputbcda77408a344d7a98a6046195dfd47f --overwrite|g.region rast=outputbcda77408a344d7a98a6046195dfd47f|r.out.gdal -c createopt="TFW=YES,COMPRESS=LZW" input=outputbcda77408a344d7a98a6046195dfd47f output="C:\Users\IACOPO~1.BOR\AppData\Local\Temp\processing\03d92082eed7415b98b492b4eed62250\output.tif"

---
Using my script, launched by Python Console within QGis:
---
ALGORITHM|Tue Jul 21 2015 14:39:44|processing.runalg("grass:v.surf.idw","C:\\Users\\iacopo.borsi\\.qgis2\\python\\plugins\\processing\\tests\\data\\points.shp",12,2,"PT_NUM_A",False,"270778.601980 , 270855.745301, 4458921.978139, 4458983.848803 ",10,-1,0.0001,None)
INFO|Tue Jul 21 2015 14:39:44|GRASS execution commands|g.proj -c proj4="+proj=utm +zone=30 +ellps=intl +towgs84=-87,-98,-121,0,0,0,0 +units=m +no_defs"|v.in.ogr min_area=0.001 snap=-1 dsn="C:\Users\iacopo.borsi\.qgis2\python\plugins\processing\tests\data" layer=points output=tmp14374823847716 --overwrite -o|g.region n= 4458983.848803  s= 4458921.978139 e= 270855.745301 w=270778.601980  res=10|v.surf.idw input=tmp14374823847716 npoints="12" power="2" column="PT_NUM_A" output=output86e01c9844a44af89394d73b4f384b5e --overwrite|g.region rast=output86e01c9844a44af89394d73b4f384b5e|r.out.gdal -c createopt="TFW=YES,COMPRESS=LZW" input=output86e01c9844a44af89394d73b4f384b5e output="C:\Users\IACOPO~1.BOR\AppData\Local\Temp\processing\96562ff5412640439c7dd19dffe60ac0\output.tif"
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