ImportError: No module named 'cplex' Python on Linux

Question

I am trying to run python scripts on a HPC machine (RedHatEntrepriseServer). CPLEX module is already installed by adminastrators but I still have this error in importing cplex module in python.

ImportError: No module named 'cplex'

I know it is common error and I found that I may need to update PYTHONPATH variable with cplex home directory, but I can't find this home directory. Does anyone have an idea or suggestion to solve this problem?!

Many thanks!

@danche: can you please detail what I can add in '~/.bashrc' file? — Betty, Jul 21 '17 at 10:15
@skr: How can I use the commands? ( `locate cplex` doesn't give any output) — Betty, Jul 21 '17 at 10:18
@danche : Thank you for the command, but I don't know and can't find cplex path... — Betty, Jul 21 '17 at 10:49
@Betty 1st you have to do `updatedb` command then do `locate cplex` command — skr, Jul 21 '17 at 10:50
@skr: `updatedb` returns this message `updatedb: can not open a temporary file for '/var/lib/mlocate/mlocate.db' ` (I am a beginner and occasional user of Linux and I don't know what it does mean exactly). Thanks! — Betty, Jul 21 '17 at 12:49
@Betty you have to be root/super user while running `updatedb`. — skr, Jul 21 '17 at 13:12
@skr: unfortunately, I don't root rights... thank you for the feedback anyway! — Betty, Jul 21 '17 at 13:19
@Betty Try find command `find / -iname "cplex"` only problem is it will take time. — skr, Jul 21 '17 at 13:24
@skr: Even it took a quite long time, I was able to find the proper cplex directory. Thank you! — Betty, Jul 21 '17 at 16:22

score 1 · Answer 1 · answered Jul 21 '17 at 16:53

1

As mentioned in the comments, setting the PYTHONPATH environment variable is a perfectly reasonable solution here. Using PYTHONPATH has advantages, such as allowing you to easily switch between multiple versions of the CPLEX Python API. However, another option would be to ask your system administrator to install the cplex module. My guess is that they installed CPLEX Optimization Studio, but they did not actually install the CPLEX Python API into the system's default Python interpreter using the setup.py script (that is an optional step that would need to be performed separately). See the relevant documentation here. Yet another option would be for you to setup your own Python environment using virtualenv (see, for example, here).

answered Jul 21 '17 at 16:53

rkersh

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the administrators have already installed cplex module but the access to cplex directory was hidden. Thank you for the additional information! – Betty Jul 22 '17 at 22:47
1

Based on the path you're using in your `PYTHONPATH` the cplex module has *not* been installed using the `setup.py` script. Under normal circumstances, we would expect to see a [site-packages](https://stackoverflow.com/questions/31384639/what-is-pythons-site-packages-directory) directory in the path. The COS installer copies the files on to the hard-drive, but it does not put them in the Python search path. If `setup.py` had been used, then you would not need to set `PYTHONPATH`. At any rate, I'm glad you found a solution. – rkersh Jul 24 '17 at 19:58

score 0 · Accepted Answer · answered Jul 24 '17 at 17:00

Thanks to skr and danche comments, here is how I solved the problem:

I looked for cplex location by using this command:

find / -iname "cplex"

Then I updated the PYTHONPATH variable with this location:

export PYTHONPATH=$PYTHONPATH:/local/software/cplex/12.6.1/cplex/python/2.6/x86-64_linux

I updated my .bashrc file with last command so each time I log in it is set automatically.

ImportError: No module named 'cplex' Python on Linux

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