[GIS] Using the Processing Framework in QGIS 2.0

importpyqgispythonqgisqgis-processing

I am writing a plugin for QGIS 2.0, and I want to use the processing framework to call some functions.

When I open the pyhton console inside QGIS, I am able to call it like this:

    >> import processing

And then, for instance:

    >>> processing.alglist()

However, if I try to import it in my Python Plugin, it fails to find the processing include:

    from qgis.core import *
    from qgis.gui import *
    import processing

I googled the problem and found this directives:

    from processing.core.Processing import Processing
    from processing.core.ProcessingConfig import Setting, ProcessingConfig

But unfortunately it also does not work for me :-/

Does anybody know how to include the qgis processing framework in a plugin, and how to call the algorithm (lets say for instance "processing.runalg(…)

I really appreciate your answers, as I found many explanations on how-to do it in the Python console, but not outside QGIS :-/

Thanks again for your time and have a nice day,
Joana

Best Answer

Ok, I will answer my own question. Using *exactly*the same imports as in the python console works; is just a problem of pydev, that doesn't recognize the libraries (I probably need to add a reference in the project somewhere)

Related Solutions

Terminating Python Scripts in QGIS Processing Framework

first thing, osgeo.gdal is for pure Python scripting:

from osgeo import gdal  
raster  = gdal.Open('your.tif')   
raster.GetProjection()

Everything else is a problem of osgeo, and not of PyQGIS, since you use 2 QGIS existing layers:

 ##raster_1=raster  
 ##raster_2=raster

you don't need it. To process the layers, the correct code is:

raster_1 = processing.getobject(raster_1)   
raster_2 = processing.getobject(raster_2)

an the crs is given by:

new_proj = raster.crs()

second thing, you cannot load a raster in QGIS without projection (if not yet existing, it is chosen by QGIS, according to some criteria):

enter image description here

So your first condition if proj is None:, is unnecessary and your script become (you don't need a list with only two layers):

raster_1 = processing.getobject(raster_1)
raster_2 = processing.getobject(raster_2)
if raster_1.crs()==raster_2.crs():
     action
else:
     WrongCRS()

and the script terminate by himself.

in the last version of the processing module, it is now:

processing.getObjects()

For terminate the script, you can embed your script in a function and use sys.exitfunc() (I use the Python console to to see the results)

example:

import atexit
.....
def all_done():
    message = '- Rasters must have the same CRS!\n\nExecution cancelled!'
    print message   
atexit.register(all_done)
raster_1 = processing.getObject(raster_1)
raster_2 = processing.getObject(raster_2)
def main():
    if raster_1.crs() != raster_2.crs():
         sys.exitfunc()
    else:
          message = "ok"
          print message
          continue
main()

Result in the Python console:

enter image description here

[GIS] Running GRASS functions in QGIS 2.4 from python console

r.in.gdal is a command to import rasters into GRASS GIS, not into QGIS

There are two options to use GRASS GIS in QGIS:

1) with the grass plugin

you are working in GRASS GIS and you can use r.in.gdal in the Python console of GRASS GIS to import a raster into a Location/Mapset.

2) from processing

you are working in QGIS with a "virtual" Location/Mapset that has nothing to do with the Location/Mapset of 1), therefore r.in.gdal is useless -> use the the PyQGIS solution in the Python console of QGIS

You can also use osgeo.gdal to import a raster into a GRASS GIS Location/Mapset.

Best Answer

Related Solutions

Terminating Python Scripts in QGIS Processing Framework

[GIS] Running GRASS functions in QGIS 2.4 from python console

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