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When I try to execute this code:

 from qgis.core import *

 QgsApplication.setPrefixPath("/usr/lib/qgis", True)
 app = QgsApplication([], True)
 app.initQgis()


 layer = QgsVectorLayer('/home/city.shp',"p", "ogr")
 QgsProject.instance().addMapLayers([layer])

 shp_path = '/home/points.shp'
 csv_path = '/home/a.csv'
 tag_save_as_shp = '/home/sep.shp'

 layerInput = QgsVectorLayer(shp_path, "cells", "ogr")
 csvInput = QgsVectorLayer(csv_path, "Table_csv", "ogr")
 QgsProject.instance().addMapLayer(layerInput, False)
 QgsProject.instance().addMapLayer(csvInput, False)
 # joining csv with shp
 csvField = 'Square-ID'
 shpField = 'cellId'
 joinObject = QgsVectorLayerJoinInfo()
 joinObject.setJoinFieldName(csvField)
 joinObject.setTargetFieldName(shpField)
 joinObject.setJoinLayerId(csvInput.id())
 joinObject.setUsingMemoryCache(True)
 joinObject.setJoinLayer(csvInput)
 joinObject.setPrefix('')
 layerInput.addJoin(joinObject)
   QgsVectorFileWriter.writeAsVectorFormat(layerInput,tag_save_as_shp,"CP120",layerInput.crs(),"ESRI Shapefile")

I get an error in PyCharm:

Process finished with exit code 139 (interrupted by signal 11: SIGSEGV)

But in the python console in QGIS everything works fine. Also, this code worked before two weeks from PyCharm also. I read that is about some memory violation, but I don't understand it. :/

UPDATE: If I deleted the QgsVectorFileWriter line, everything is ok. So I have problem when I try to make output..

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  • some odd things here, i would check: setPrefixPath is executed before app is instanciated, QgsProject may not exist in a standalone script, unusual path /home, do you have read/write access? Last line has an indent, also will be overwriting the input shapefile?
    – Andreas Müller
    Commented Nov 2, 2018 at 7:58
  • Thank you. :)))) It was because of SetPrefixPath. Earlier was working on that way. Please put this as an answer and I will accept it. :)
    – user123480
    Commented Nov 2, 2018 at 8:21

1 Answer 1

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In a standalone python script, a qgis app object must be instantiated before you specify the qgis prefix path. So this becomes 

app = QgsApplication(argv, True)
app.setPrefixPath(path_to_qgis_libs)

QgsApplication.setPrefixPath() may also work, if you put it after app object instantiation, i didn't try this.

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