Originally posted by: WJvanHoeve

Hello,

After trying for several days, I am still struggling with getting my Python DOCplex interface up and running.

Specs:  Windows 8.1 Pro; Python3.6.4; CPLEX 12.8

I installed CPLEX Studio 12.8, and followed the steps to run setup.py as described here:

https://www.ibm.com/support/knowledgecenter/SSSA5P_12.6.0/ilog.odms.cplex.help/CPLEX/GettingStarted/topics/set_up/Python_setup.html

When I run a model, for example diet.py in the examples, the model is compiled well, but unable to solve.  The error message is "CPLEX DLL not found".

Apparently Python does not know where to find the cplex dll, and neither do I...

(I attempted to define the proper PYTHONPATH variable, but without success so far.)

Some additional information:

- The documentation states that I can "set the environment variable PYTHONPATH to yourCPLEXhome/python/PLATFORM".  However, there is no directory indicating a platform under my CPLEX python directory.

- The diet.py example file states that my PYTHONPATH variable is used to search for cplex_config.py.  I was unable to locate this file on my machine.

If anyone can offer any help, that would be much appreciated.

In your CPLEX installation there should be a folder cplex/python/2.7/x64_win64. That is where your PYTHONPATH variable should point to (if you use Python 3.5 or 3.6 then replace the 2.7 in the path by 3.5 or 3.6). Can you please double-check that your PYTHONPATH contains the absolute path of this folder? Also, can you print your PYTHONPATH from within your Python script to make sure it looks as expected:

import os
print(os.environ['PYTHONPATH'])

Originally posted by: WJvanHoeve

The contents of my cplex/python folder are:

 Directory of C:\Program Files\IBM\ILOG\CPLEX_Studio128\python

02/05/2019  04:27 PM    <DIR>          .
02/05/2019  04:27 PM    <DIR>          ..
02/05/2019  04:27 PM    <DIR>          dependencies
02/19/2019  04:53 PM    <DIR>          docplex
02/05/2019  04:27 PM    <DIR>          examples
02/20/2019  10:24 PM            11,350 LICENSE.txt
02/20/2019  10:24 PM             3,062 README.md
02/20/2019  10:24 PM             4,040 setup.py
               3 File(s)         18,452 bytes

I ran 'setup.py' in this folder, and also manually added this path to my PYTHONPATH environment variable.

This is the output of PYTHONPATH from within Python:

C:\Program Files\IBM\ILOG\CPLEX_Studio128\python>python
Python 3.6.4 (v3.6.4:d48eceb, Dec 19 2017, 06:04:45) [MSC v.1900 32 bit (Intel)]
 on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import os
>>> print(os.environ['PYTHONPATH'])
C:\Program Files\IBM\ILOG\CPLEX_Studio128\python
>>>

Do you have a folder C:\Program Files\IBM\ILOG\CPLEX_Studio128\cplex\python\3.6\x64_win64? Judging from your output I think that is the folder which contains the DLLs and to which PYTHONPATH should point. If you have that folder, can you try setting PYTHONPATH to include it?

Originally posted by: WJvanHoeve

Yes, that folder exists and I added it to the PYTHONPATH:

>>> import os

>>> print(os.environ['PYTHONPATH'])
C:\Program Files\IBM\ILOG\CPLEX_Studio128\cplex\python\3.6\x64_win64
>>>

In Jupyter, now at least CPLEX is being recognized, but I received the message "Exception: CPLEX 12.8.0.0 is not compatible with this version of Python."

In the command prompt, however, still get the error message "CPLEX DLL not found".  It also gives me the warning that "docplex is not officially supported on 32 bits, which made me realize that I was running a 32-bit version of Python :(.

So, I installed the 64-bit version of Python 3.6.8, and re-executed all installation steps, including the setup.py -- this time from the proper path.

Unfortunately, now I get a different error message: " ModuleNotFoundError: No module named 'docplex' ", see:

C:\Program Files\IBM\ILOG\CPLEX_Studio128\python\examples\mp\modeling>python diet.py
Traceback (most recent call last):
  File "diet.py", line 13, in <module>
    from docplex.mp.model import Model
ModuleNotFoundError: No module named 'docplex'
 

Maybe it is a good idea to uninstall everything and restart from scratch.

If the module "docplex" is not found then this means that it is not in the default places where Python looks for modules. You can try to add the docplex directory to PYTHONPATH as well. Or make sure that the python you invoke on the command line is indeed the one you intend to invoke. Maybe always use an absolute path to invoke python. Even when calling setup.py.

Originally posted by: WJvanHoeve

I uninstalled and restarted from scratch, but realized that my anaconda installation is based on Python 3.7 (which is not yet supported CPLEX), so I did not use conda.

• To install docplex I avoided conda, and used pip instead (https://pypi.org/project/docplex/)
• To install the Python API, I now used the correct path to run setup.py (as indicated on https://www.ibm.com/support/knowledgecenter/SSSA5P_12.8.0/ilog.odms.cplex.help/CPLEX/GettingStarted/topics/set_up/Python_setup.html)

I am happy to report that the example diet.py now runs fine :)

Just a quick note: as of CPLEX version 12.9 Python 3.7 is now supported.