[Qgis-user] Using the ##passfilename tag for R script in Processing Toolbox

[Ned Horning]

Hi -

I am trying to learn to write R scripts using the Processing Toolbox. I 
have a random forest image classification script that works in the 
processing toolkit but I'd like to modify it to do more complex tasks. I 
think I need to use the ##passfilename tag but every time I add that to 
a script I get an error that I pasted below. I tried several different 
scripts and every time I add the ##passfilename tag I get the same 
error. Does the ##passfilename tag  need other parameters? If anyone 
knows what the problem might be or has pointers about how I can find the 
problem please let me know?

This R scripting capability has a lot of potential and I'd like to write 
a guide on how to use it but I still have a lot to learn myself.

All the best,

Ned


I'm running QGIS 2.0.1 on Ubuntu 12.04. This is the error message:
--
An error has occured while executing Python code:

Traceback (most recent call last):
   File 
"/usr/share/qgis/python/plugins/processing/r/EditRScriptDialog.py", line 
95, in runAlgorithm
     alg = RAlgorithm(None, unicode(self.text.text()))
   File "/usr/share/qgis/python/plugins/processing/r/RAlgorithm.py", 
line 71, in __init__
     self.defineCharacteristicsFromScript()
   File "/usr/share/qgis/python/plugins/processing/r/RAlgorithm.py", 
line 82, in defineCharacteristicsFromScript
     self.parseDescription(iter(lines))
   File "/usr/share/qgis/python/plugins/processing/r/RAlgorithm.py", 
line 108, in parseDescription
     raise WrongScriptException("Could not load R script:" + 
self.descriptionFile + ".\n Problem with line \"" + line + "\"")
TypeError: cannot concatenate 'str' and 'NoneType' objects

Python version:
2.7.3 (default, Sep 26 2013, 20:13:52)
[GCC 4.6.3]


QGIS version:
2.0.1-Dufour Dufour, exported

Python path: ['/usr/share/qgis/python/plugins/processing', 
'/usr/share/qgis/python', '/home/nedhorning/.qgis2/python', 
'/home/nedhorning/.qgis2/python/plugins', 
'/usr/share/qgis/python/plugins', '/usr/lib/python2.7', 
'/usr/lib/python2.7/plat-linux2', '/usr/lib/python2.7/lib-tk', 
'/usr/lib/python2.7/lib-old', '/usr/lib/python2.7/lib-dynload', 
'/usr/local/lib/python2.7/dist-packages', 
'/usr/lib/python2.7/dist-packages', 
'/usr/lib/python2.7/dist-packages/PIL', 
'/usr/lib/python2.7/dist-packages/gst-0.10', 
'/usr/lib/python2.7/dist-packages/gtk-2.0', 
'/usr/lib/pymodules/python2.7', 
'/usr/lib/python2.7/dist-packages/ubuntu-sso-client', 
'/usr/lib/python2.7/dist-packages/ubuntuone-client', 
'/usr/lib/python2.7/dist-packages/ubuntuone-installer', 
'/usr/lib/python2.7/dist-packages/ubuntuone-storage-protocol', 
'/usr/lib/python2.7/dist-packages/wx-2.8-gtk2-unicode', 
'/usr/share/qgis/python/plugins/fTools/tools']