Python 2 AND Python 3 ArcGIS requirements

Question

I've in the processing of transitioning some Python 2 arcpy geoprocessing workflows to Python 3 so I can also incorporate the ArcGIS Python API into the workflows.

As such, I need both versions installed on a single computer, and both able to leverage the arcpy library.

Does that mean I need to install ArcMap AND ArcGIS Pro on my machine?  Is there any way to get this accomplished with JUST ArcGIS Pro?

DanPatterson_Retired · Answer

of course you need Pro installed, arcpy is different between the *map and *pro incarnations.  The point I was making is to skip writing python 2.7 so it will work in 3.x, the otherway around is what I have done.  The "from __future___..." are ignored by python 3.x and are only needed for convenience for the 2.7 versions that are used with ArcMap.

Rumours of ArcMap 10.7 appearing suggest that esri will continue to support the python 2.7 code base  even though there will be no updates to it beyond 2020.  At some point, maintaining 2 arcpys and 2 whatevers will wear thin and ArcMap will become 'legacy' as many of its predecessors have experienced (aka ArcMap 3.x, Avenue... even Cobol 
)

ArcGIS Pro is pretty good at not getting muddled by a python 2.7/ArcMap installation.  Which is part of the reason they use an Anaconda distribution of python and you should 'Clone' your 3.x environment since a pristine installation of *pro needs to be maintained.

/blogs/dan_patterson/2018/12/28/clone

Jay_Gregory · Answer

Sure, I can certainly write scripts with in 2.x that will work for 3.x using the __future__ module, but in order to utilize arcpy in the 3.x python (which I also need for ArcGIS Python API), I still need ArcGIS Pro installed.

DanPatterson_Retired · Answer

Server stuff aside, since I don't use one... I used python 3 to develop scripts that worked in 2.7 and arcmaps arcpy long before ArcGIS pro was around. You will notice many code bases that support python 2.x and 3.x rely on imports from the __future__ module 28.11. __future__ — Future statement definitions — Python 2.7.15 documentation So it is not uncommon to see from __future__ import (absolute_import, division, print_function, unicode_literals) from builtins import *‍‍‍ when people are writing code that needs to support the 2.7 and 3.x code base. In general skip writing for 2.7, write for 3.x since 2.7 support is being dropped or has been dropped already by many of the python packages that people might use for gis applications (ie numpy, scipy, pandas etc etc) You can also skip things altogether (I have had success with this) by writing for toolsets for use in arctoolbox in ArcGIS Pro 2.3, for example, then exporting them for use in versions of ArcMap.... /blogs/dan_patterson/2016/05/09/the-links provides links to some resources which might help make the transition... But in any event Python 2.7 Countdown is inevitable...