[Qgis-user] QGIS 2.18.X and QGIS3

[Andre Joost]

Am 07.03.18 um 15:51 schrieb Tyler Veinot:
> Anyone having issues with Python after installing the new QGIS3? My OSGeo4w
> shell only sees the Python27 install and my windows cmd only sees the
> python36 install. When I type python in OSGeo4W I get 2.7.XXXXX and a
> readout of where it is installed and such, the usual. When I type Python in
> my windows cmd I get the program could not start because python36.dll is
> missing from your computer. Using the 64bit OSGeo4W package, btw.
> When in QGIS3 if I put in print(sys.version) in the python codeblock I get
> a readout saying I am in Python 3.6. QGIS 2.18.X LTR seems to be using
> Python 2.7.XXX
> My question is, is this normal? Is the python packaged with QGIS3 somehow
> (locked) because it is an early release and not 100% ready? or do I need to
> do something to switch from one Python to another that I am not doing?

If you type set in the OSGEO4W shell, you see the PYTHONHOME variable 
set to C:\OSGEO4W\apps\Python27. So you run Python.exe from Python27.

Just type py3_env inside the shell, and the variable is reset to the 
Python36 folder. So python.exe is now started from there.

In a simple Windows terminal python will not run in either case, because 
the environment is only set correctly when starting the OSGEO4w shell.

HTH,
Andre Joost