[GIS] import qgis.core problem with QgsFeature and QgsGeometry

importpythonqgis

I've tried several previous answers to similar questions – no luck.

I run Win7. I installed QGIS 2.2.0 using the OSGeo4W 32-bit installer.

Problem 1) from qgis.core import * failed.
Solution 1) After everything related to setting Path and PYTHONPATH variables failed, I had to copy C:\OSGeo4W\apps\qgis\python\qgis to C:\Python27\Lib\site-packages (and yes, including C:\OSGeo4W\apps\qgis\python\qgis in both Path and PYTHONPATH did NOT work).

Problem 2) The above approach got the qgis.core import started, but resulted in the following error message related to QgsFeature and QgsGeometry:

Traceback (most recent call last):
  File "D:\Research\inhaca\OBIA\model_script.py", line 1, in <module>
    from qgis.core import *
  File "C:\Python27\lib\site-packages\qgis\__init__.py", line 35, in <module>
    from qgis.core import QgsFeature, QgsGeometry
ImportError: DLL load failed: The specified module could not be found.

Now I'm lost. I tried copying all files from C:\OSGeo4W\apps\qgis\include and C:\OSGeo4W\apps\qgis\lib to the respective (include and Lib) folders in C:\Python27 – still didn't work. I'm fumbling in the dark here, any pointers?

Best Answer

You need to create a batch file to bootstrap your Python file that setups the correct environment. This is the one I use for all of my standalone QGIS apps:

REM Change OSGEO4W_ROOT to point to the base install folder
SET OSGEO4W_ROOT=C:\OSGeo4W
SET QGISNAME=qgis
SET QGIS=%OSGEO4W_ROOT%\apps\%QGISNAME%
set QGIS_PREFIX_PATH=%QGIS%

REM Python Setup
set PATH=%OSGEO4W_ROOT%\bin;%QGIS%\bin;%PATH%
SET PYTHONHOME=%OSGEO4W_ROOT%\apps\Python27
set PYTHONPATH=%QGIS%\python;%PYTHONPATH%

python yourscript.py

The QGISNAME variable is only so I can swap between release qgis and dev QGIS for testing, remove if not needed.

PYTHONPATH

The PYTHONPATH is set for the cmd you launch. This means that you have to set it globally on your system

Go to Control Panel -> System-> Advanced.

Click on the 'Environment Variables' button.

In the 'System Variables' panel that appears, click New and enter PYTHONPATH in the 'Variable Name' field. In the 'Variable Value' field enter the path to QGIS.

Or you can set it directly on the cmd command line just before launching the python interpreter with :

set PYTHONPATH=%PYTHONPATH%;C:\My_python_lib

PATH

The DLL which will be used by the qgis python module must be in your path. Just as you set the PYTHONPATH above, set the PATH environment variable so that it contains the directory where qgis_core.dll is located.

The directory to add is probably D:\Program Files (x86)\Quantum GIS Wroclaw\apps\qgis But check that qgis_core.dll is really there.

OSGEO4W

As was suggested in another answer, OSGEO4W install and sets everything up for you. It will install another Python though, which can complicate things when you want to install third party Python modules not available in OSGEO4W.

You would as well get the latest QGIS version too, which is 1.7.4 (1.8 coming soon).

[GIS] Running Python outside of QGIS – (ImportError: No module named qgis.core)

This solution worked for me in Windows 7x64 SP1 with Python 2.7.13-64bit and QGIS 2.14.9x64 standalone install (important: Python and QGIS architectures must match). This solution involves virtualenv (install instructions) which means you won't need to play with Python environment variables which can be tricky if you're doing other Python development with different versions of Python.

Editing Path

Edit the PATH variable by going to Control Panel>System>Advanced system settings then click on Environment Variables in the below window.

Edit the PATH User Variable and add ;C:\Program Files\QGIS Essen\bin\;C:\Program Files\QGIS Essen\apps\qgis-ltr\bin, note the version Essen as well as the use of qgis-ltr\bin here. The latter was necessary in order for Python to be able to find the qgis_core.dll.

Create a Virtual Environment

Create a new virtual environment in the command line: virtualenv qgisenv -p "C:\path\to\Python27.exe" specifying the Python 2.7 location. Note this will create a folder for your virtual environment, you should put any projects you develop in here.

Next add paths to the installed QGIS python libraries to the virtual environment's site-packages folder using .pth files. For example in QGIS 2.14.9 python packages can be found at the following locations (why?), so create a file qgisenv\Lib\site-packages\qgis.pth with:

C:\Program Files\QGIS Essen\apps\qgis-ltr\python
C:\Program Files\QGIS Essen\apps\Python27\
C:\Program Files\QGIS Essen\apps\Python27\Lib\
C:\Program Files\QGIS Essen\apps\Python27\Lib\site-packages
C:\Program Files\QGIS Essen\bin
C:\Program Files\QGIS Essen\include
C:\Program Files\QGIS Essen\apps\qgis-ltr\bin

this list can probably be shortened

Activate Environment and Test

Back in the Command Prompt cd into the qgisenv directory and activate the virtual environment with Scripts\activate

Then open a python console and type

>>> from qgis.core import *

And you should be good to go!

How to use an IDE?

If you use anaconda and Spyder, you could use conda to set up the environment and then call spyder after activating the environment. Other IDEs might have the option of setting a virtual environment from the settings.