ImportError: No module named when module is there

Question

I usually run python2 but I am playing with python3. Right now I am confused as to why I am getting this error.

When I run the command ./test_web_events.py in the tests directory, I get:

Traceback (most recent call last):
  File "./test_web_events.py", line 21, in <module>
    import qe.util.scratchstore as scratchstore
ImportError: No module named 'qe'

However my project structure has qe directory in it:

/python_lib
   Makefile
   /qe
      __init__.py
      /tests
         __init__.py
         test_web_events.py
      /util
         __init__.py
         scratchstore.py
      /trinity
         __init__.py

I tried moving my /tests directory into /python_lib but I am still getting the same error:

MTVL1289dd026:python_lib bli1$ ls
Makefile    qe      rundata     setup.sh    tests
MTVL1289dd026:python_lib bli1$ python3 tests/test_web_events.py 
Traceback (most recent call last):
  File "tests/test_web_events.py", line 21, in <module>
    import qe.util.scratchstore as scratchstore
ImportError: No module named 'qe'

Here is my sys.path for python2

>>> import sys
>>> print sys.path
['', '/Library/Python/2.7/site-packages/pip-1.5.6-py2.7.egg', '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python27.zip', '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7', '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-darwin', '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-mac', '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-mac/lib-scriptpackages', '/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python', '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-tk', '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-old', '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload', '/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/PyObjC', '/Library/Python/2.7/site-packages']

sys.path for python3

>>> print(sys.path)
['', '/Library/Frameworks/Python.framework/Versions/3.4/lib/python34.zip', '/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4', '/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/plat-darwin', '/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/lib-dynload', '/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/site-packages']

Answer 1

The issue is that /python_lib is not in Python path. The behavior is the same on both Python 2 and 3.

In general, do not run scripts from within (inside) a Python package, run them from the top-level directory instead:

/python_lib$ python -m qe.tests.test_web_events

Thus /python_lib is in Python path and /python_lib/qe/tests is not. It assumes that there is tests/__init__.py file.

Do not modify sys.path manually. It may lead to subtle bugs related to importing modules. There are better alternatives e.g., if you don't want to run the scripts from /python_lib, just install the development version:

(your_virtualenv)/python_lib$ pip install -e .