setting pycharm as a pyqgis ide

1tand-alone PyQGIS scripts with OSGeo4W
2PyQGIS scripts are great to automate spatial processing workflows. It’s easy to run these scripts inside QGIS but it can be even more convenient to run PyQGIS scripts without even having to launch QGIS. To create a so-called “stand-alone” PyQGIS script, there are a few things that need to be taken care of. The following steps show how to set up PyCharm for stand-alone PyQGIS development on Windows10 with OSGeo4W.
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4An essential first step is to ensure that all environment variables are set correctly. The most reliable approach is to go to C:\OSGeo4W64\bin (or wherever OSGeo4W is installed on your machine), make a copy of qgis-dev-g7.bat (or any other QGIS version that you have installed) and rename it to pycharm.bat:
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8Instead of launching QGIS, we want that pycharm.bat launches PyCharm. Therefore, we edit the final line in the .bat file to start pycharm64.exe:
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12In PyCharm itself, the main task to finish our setup is configuring the project interpreter:
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16First, we add a new “system interpreter” for Python 3.7 using the corresponding OSGeo4W Python installation.
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20To finish the interpreter config, we need to add two additional paths pointing to QGIS\python and QGIS\python\plugins:
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24That’s it! Now we can start developing our stand-alone PyQGIS script.
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26The following example shows the necessary steps, particularly:
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28Initializing QGIS
29Initializing Processing
30Running a Processing algorithm
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63import sys
64 
65from qgis.core import QgsApplication, QgsProcessingFeedback
66from qgis.analysis import QgsNativeAlgorithms
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68QgsApplication.setPrefixPath(r'C:\OSGeo4W64\apps\qgis-dev', True)
69qgs = QgsApplication([], False)
70qgs.initQgis()
71 
72# Add the path to processing so we can import it next
73sys.path.append(r'C:\OSGeo4W64\apps\qgis-dev\python\plugins')
74# Imports usually should be at the top of a script but this unconventional 
75# order is necessary here because QGIS has to be initialized first
76import processing
77from processing.core.Processing import Processing
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79Processing.initialize()
80QgsApplication.processingRegistry().addProvider(QgsNativeAlgorithms())
81feedback = QgsProcessingFeedback()
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83rivers = r'D:\Documents\Geodata\NaturalEarthData\Natural_Earth_quick_start\10m_physical\ne_10m_rivers_lake_centerlines.shp'
84output = r'D:\Documents\Geodata\temp\danube3.shp'
85expression = "name LIKE '%Danube%'"
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87danube = processing.run(
88    'native:extractbyexpression',
89    {'INPUT': rivers, 'EXPRESSION': expression, 'OUTPUT': output},
90    feedback=feedback
91    )['OUTPUT']
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93print(danube)
94<div class="open_grepper_editor" title="Edit & Save To Grepper"></div>
95