Import error in IPython notebook only with coopr.pyomo

Question

I'm using the mathematical modelling package coopr.pyomo successfully in both script files and interactively on the ipython console. However, if I try a simple import coopr.pyomo in an IPython notebook started by ipython notebook, I get the following error message:

ImportError                               Traceback (most recent call last)
<ipython-input-1-ff8219fceacd> in <module>()
----> 1 import coopr.pyomo

ImportError: No module named pyomo

Other imports (both buitlins and custom packages) work without trouble. Any ideas where to look for a cause?

Environment: Python 2.7 (32 bit) on Windows 7, IPython 0.13.2, Coopr release 3.2.6148.

Edit: more diagnostics

Indeed, coopr can be imported, yet has not __file__ attribute. If I display __dict__, I get the correct path:

{'__name__': 'coopr', 
 'data': <module 'coopr.data' (built-in)>, 
 '__doc__': None, 
 '__path__': ['C:\\Python27\\lib\\site-packages\\coopr']}

If I browse in that directory, I find that all submodules (e.g. coopr.pyomo) are located in the src subdirectory. data seems to be a spurious directory with some test (test_baselines.py, test_perf.py) and example (diet1.py) files.

Edit #2: it's getting closer (I think)

The issue seems to be caused by the peculiar way how the windows installer of Coopr works. According to the Installation Notes, Coopr sits encapsulated in its own virtual sandbox. This is underlined by its default installation directory suggestion CH := C:/Packages/Coopr. Last time, I ignored this sign and simply installed it to Python's site-packages folder. Now, for testing, I re-installed Coopr to this external directory. Coopr/Pyomo still can be successfully imported from within a (I)Python session, as sys.path is extended by all the subdirectories of the CH/src/ directory.

However, these subdirectories look different from other packages I am used to. For example, src/coopr.pyomo only contains a setup.py, while __init__.py sits in CH/src/coopr.pyomo/coopr/pyomo. While IPython seems to be able to find the packages, IPython notebook -- although the search path is identical -- seems to get confused by the way the packages are organised.

How did you install the package? Your last paragraph describes it like it was copied from source straight into the site-packages directory, not by running python setup.py install. — user707650
Using the official installer. I re-examined the procedure, see Edit #2 for details. — ojdo

Unknown Unknown · Accepted Answer · 2013-07-15T14:03:37

I have to guess, but:

Try something like the following in the notebook:

import coopr
print coopr.__file__

It looks like you're picking up a different coopr module than the installed one, and the __file__ attribute should tell you which one you're using. Perhaps there's a script called coopr; such a script would not contain a submodule pyomo.

Why would this only happen in the IPython notebook and not in the IPython console? My guess is that, if there is indeed a different coopr module, it lives in your home directory or somewhere else on the system that the IPython notebook uses as its "base". The IPython console base directory is where you started it, but the IPython notebook is probably decoupled and has a default base directory. I don't know how the notebook is run under Windows, so I can't tell you what that default is and where to look, but the above code could very well show you that.

Import error in IPython notebook only with coopr.pyomo

2 Answers