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I wrote several python scripts called by my main.py script. In one of those scripts I create a vector layer by polygonizing a raster layer. As the layer is really heavy and as I don't need it as an output, I create it in memory.

result = processing.runalg('gdalogr:polygonize',layer,"lu_majorit", None)
polygonLayer = processing.getObject(result['OUTPUT'])

Then I can use the layer in my file. But I would like to use this layer from another script and I don't succeed.

Here is what I've tried :

in my first script :

result = processing.runalg('gdalogr:polygonize',layer,"lu_majorit", None)
polygonLayer = processing.getObject(result['OUTPUT'])
return polygonLayer

in my main:

polygonLayer=script1(...)
script2(polygonLayer,...)

in my second script :

cLayer =QgsVectorLayer("Polygon?crs=epsg:4326", "OUTPUT", "memory")

or:

cLayer =QgsVectorLayer("polygonLayer", "OUTPUT", "ogr")

Those two ways failed to load the layer.

I tried also by giving the path with : script 1 :

myfilepath= polygonLayer.dataProvider().dataSourceUri()
return myfilepath

script2:

cLayer =QgsVectorLayer(myfilepath, "OUTPUT", "ogr")

This way gives me an invalid syntax.

Does someone know how to do ?

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  • instead of runalg you can use runandload ( load it to QgsMapLayerRegistry and use it later ) like here gis.stackexchange.com/questions/76594/… Jul 17, 2017 at 13:40
  • @HichamZouarhi When I replace runalg by runanload I get this message error : "polygonize has no attribute 'getitem'"
    – J.Delannoy
    Jul 17, 2017 at 15:19

1 Answer 1

1

If both your python files are in the same directory, something like this should work:

script2

def myFunction():
    result = processing.runalg('gdalogr:polygonize',layer,"lu_majorit", None)
    polygonLayer = processing.getObject(result['OUTPUT'])
    return polygonLayer

main script

import script2 # for python file named script2.py

polygonLayer = script2.myFunction()

If they are not in the same directory you may use the sys.path.append() method to append the path of the python script you want to add:

sys.path.append('//path/to/other/script/directory')
import script2
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  • Thank you for your answer. My files are in the same directory and I tried this method. But this does not work. It failed to load the layer
    – J.Delannoy
    Jul 19, 2017 at 12:43
  • Can you expand more on what you mean by "failed to load the layer"?
    – artwork21
    Jul 19, 2017 at 13:44
  • It works !!! I think that I tried too many ways so I mixed up some ... So now that I cleaned my code to explain better my problem, there is no problem anymore. So thank you :)
    – J.Delannoy
    Jul 20, 2017 at 6:50

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