[GIS] Setting PYTHONPATH for compiled QGIS version on Linux

pyqgis

I'm trying to set the PYTHONPATH in order to be able to load the qgis classes in a python console (not the QGIS Python one).

I followed some resources I've found (PYQGIS Cookbook, and others) but I get still the same error message:

>>> import qgis.core
ImportError: No module named qgis.core

I'm pretty sure the problem is that I have a compiled version of QGIS and of course the PATHs suggested are different.

The folder of my QGIS is:

/home/user/QGIS-master

I tried to add the following to the .bashrc file in order to have the PATH but nothing changed (still the error of above):

export PYTHONPATH=/home/user/QGIS-master/python/

Someone has an idea of which is the correct PATH I have to export?

Best Answer

The folder for the PYTHONPATH must be the compiled one and not the source one. Your build path should be something like /home/user/QGIS-master/<builddir>/output/. I am guessing you are running from build your QGIS version so you just export the environment var like:

export PYTHONPATH=/home/user/QGIS-master/<builddir>/output/python/

maybe it also could be necessary to set LD_LIBRARY_PATH (as mentioned in PyQGIS Cookbook).

export LD_LIBRARY_PATH=/home/user/QGIS-master/<builddir>/output/lib/

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[GIS] How to Setup Python to recognize QGIS

It looks like you have a similar problem to one I had. Though the specifics of the paths are different I believe that a similar solution can work. See my solution in this post.

What is happening is that it is not just the PYTHONPATH which is read but also the PATH variable. On load QGIS appends the paths of the osgeo binaries to the path, which means they get read last. That means the ArcGIS location is found first and Windows looks no further.

What you don't want to do is muck up your ArcGIS install by playing with the main PATH variable (where there will be a reference to the Arc Python directory). However, if you tell QGIS to reverse the sys.path variable as the first thing it does, it will read the osgeo paths first and ignore the Arc Python instalation. This change is only apparent within the specific Python session (i.e. it has no effect on the actual PATH or PYTHONPATH variables stored on your computer and neither is it permanent, so will be safe as far as ArcGIS is concerned and less dangerous than editting your PATH variable as this could end up breaking Arc with the same problem but the other way around).

Depending on your install, you might want to change my solution to something like (based on what I read in your question):

import sys
sys.path.extend([r"C:\Quantum_GIS_Lisboa\apps\qgis\python",r"C:\Quantum_GIS_Lisboa\apps\qgis\bin"])
sys.path.reverse()

If you have used osgeo4w to install QGIS this will be unnecessary, but you could do it anyway as a belt-and-braces approach - it won't hurt). I suspect you will also need to add the lines at the start of the set_qgis_01.py file (I did mine in the GDALTOOLS.py file because that's where my conflict manifested itself).

[GIS] Where exactly are qgis.gui and qgis.core located

This is the correct path setup:

@echo off
SET OSGEO4W_ROOT=c:\IMS\Qgis
call "%OSGEO4W_ROOT%"\bin\o4w_env.bat
call "%OSGEO4W_ROOT%"\apps\grass\grass-6.4.2\etc\env.bat

set PYTHONPATH=C:\OSGeo4W\apps\qgis\python
Set PATH=C:\OSGeo4W\apps\qgis\bin;%PATH%
set QGISHOME=C:\OSGeo4W\apps\qgis\

qgis.core and qgis.gui are located in the qgis\python\qgis folder but you only set PYTHONPATH to the qgis\python folder because qgis is a package.

Best Answer

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[GIS] Where exactly are qgis.gui and qgis.core located

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