Python API picking up wrong GAMS version

GAMS
1

I’m trying to install the GAMS Python API using Anaconda, but it is picking up an old version of GAMS (38) that I have installed on my machine. I have GAMS 38-46 currently installed, and am trying to use the api with Gams 46.4.0, the latest version installed on my machine.

I started by creating a new environment in Anaconda, and in a command line entered:

(gams_py46) C:\Users\myusername>pip install gamsapi[all]==46.4.0

which seemed to install successfully. Then (following the instructions in https://www.gams.com/latest/docs/API_PY_GETTING_STARTED.html), I entered

python -c "import gams; print(f'API OK -- Version {gams.__version__}')"

which gave me

Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "C:\GAMS\38\apifiles\Python\gams\gams\__init__.py", line 32, in <module>
    from .workspace import *
  File "C:\GAMS\38\apifiles\Python\gams\gams\workspace.py", line 32, in <module>
    from .database import *
  File "C:\GAMS\38\apifiles\Python\gams\gams\database.py", line 26, in <module>
    from gdxcc import *
ModuleNotFoundError: No module named 'gdxcc'

so clearly it is trying to get something from GAMS 38 instead of GAMS 46. So I tried

(gams_py46) C:\Users\myusername>python -m site

and got

sys.path = [
    'C:\\Users\\myusername',
    'C:\\GAMS\\38\\apifiles\\Python\\gams',
    'C:\\Users\\myusername\\%PYTHONPATH%',
    'C:\\Anaconda3\\envs\\gams_py46\\python311.zip',
    'C:\\Anaconda3\\envs\\gams_py46\\DLLs',
    'C:\\Anaconda3\\envs\\gams_py46\\Lib',
    'C:\\Anaconda3\\envs\\gams_py46',
    'C:\\Anaconda3\\envs\\gams_py46\\Lib\\site-packages',
]
USER_BASE: 'C:\\Users\\myusername\\AppData\\Roaming\\Python' (exists)
USER_SITE: 'C:\\Users\\myusername\\AppData\\Roaming\\Python\\Python311\\site-packages' (doesn't exist)
ENABLE_USER_SITE: True

The instructions tell me to correct the GAMS path in the file sitecustomize.py, but there is no such file in the USER_BASE folder (and the USER_SITE folder doesn’t exist), and any other files I can find with this name don’t have a C:\GAMS\38 path in them (or any other explicit GAMS path for that matter).

I don’t really want to uninstall GAMS 38 as I need to retain that for the working version of the code I want to upgrade. How do I fix this path issue? Thanks!

2

Hi,

Something seems to put in the GAMS 38 path into your configuration. Have you checked if the PYTHONPATH environment variable is set? Run from the Anaconda command prompt:

echo %PYTHONPATH%

Best,
Clemens

3

Hello,

It sounds to me like the GAMS 38 in the sitecustomize.py file is confusing your fresh conda install.

Many years ago I used the Python site package, but once I started to use miniconda I dropped it completely. I found that the two don’t work well together. And at some level they are fundamental incompatible. With conda I want to create a self-contained environment that is independent of other Python stuff (conda or otherwise). But with the site package, I am sharing settings between Python versions.

-Steve

4

Hi Clemens,

Yes, thanks, I think that’s it! When I put that into the command prompt, I get

C:\GAMS\38\apifiles\Python\gams;%PYTHONPATH%

and I remember changing something along those lines a year or two ago when we were setting up the original connection between GAMS and Python.

To remove it, in my Windows search I looked up “edit environment variables for your account”, which opened the Environment Variables box (similar to but distinct from the System Environment Variables). In the top box User variables, I had a couple of variables that had values that included the path to GAMS 38. I deleted those and closed that box, closed and restarted Anaconda, then checked the echo %PYTHONPATH% command again, and the reference to GAMS 38 was gone. I then reinstalled the API using the commands above and checked the install, and this time it told me it was using the right version of GAMS:

C:\Users\myusername>python -c "import gams; print(f'API OK -- Version {gams.__version__}')"
API OK -- Version 46.4.0

Now I just need to try using it…