Python import error from xx.xx import * : no module named

Question

Here is my file structure:

-test

--m1

---t.py

--m2

---__init__.py

---utils.py

t.py:

from m2.utils import *
print foo()

utils.py:

def foo():
  return 5

__init__.py is empty

It works in my local environment (macOS Sierra python 2.7.10):

Shangtong@Shangtong:~/GitHub/PaperReplication/test$ python m1/t.py
5
Shangtong@Shangtong:~/GitHub/PaperReplication/test$ echo $PYTHONPATH
:/Users/Shangtong/DevelopmentKits/libsvm-3.20/python

However it doesn't work in my server (Python 2.7.8):

[shangton@jasper test]$ python m1/t.py
Traceback (most recent call last):
  File "m1/t.py", line 1, in <module>
    from m2.utils import *
ImportError: No module named m2.utils
[shangton@jasper test]$ ls -al
total 16
drwxrwxr-x 4 shangton shangton 4096 Jan 28 09:10 .
drwx------ 4 shangton shangton 4096 Jan 28 10:09 ..
drwxrwxr-x 2 shangton shangton 4096 Jan 28 09:12 m1
drwxrwxr-x 2 shangton shangton 4096 Jan 28 10:09 m2
[shangton@jasper test]$ echo $PYTHONPATH
/global/software/python/Python-2.7.8/lib/python2.7/site-packages/:/global/software/python/Python-2.7.3/lib/python2.7/site-packages/:~/PaperReplication/:~/test/m2:~/test

If you had a m1/__init__.py, you could run python -m m1.t — Charles Duffy
– Charles Duffy, Commented Jan 28, 2017 at 17:26
...or if you set PYTHONPATH=$PWD, then this should work immediately as you intend. — Charles Duffy
– Charles Duffy, Commented Jan 28, 2017 at 17:26
~ isn't guaranteed to expand -- use $HOME, not ~, when setting environment variables. Python may do it manually -- there's a library function for the purpose -- but many programs won't. — Charles Duffy
– Charles Duffy, Commented Jan 28, 2017 at 17:27

Charles Duffy · Accepted Answer · 2017-01-28 17:39:32Z

2

You're demonstrating that your PYTHONPATH contains:

~/test/m2:~/test

However, ~ is not actually a valid PATH component! It's a hint to your shell to replace that character with your home directory (when unquoted, in the first position in a word, and otherwise where other conditions are met) -- but Python is not your shell, and if your shell didn't honor that hint when you were setting the environment variable (perhaps because, being in the middle of a string, it wasn't in leading position), it won't be honored later unless Python explicitly calls os.path.expanduser().

When setting an environment variable, use $HOME:

PYTHONPATH=$HOME/test

edited Jan 28, 2017 at 17:39

answered Jan 28, 2017 at 17:29

Charles Duffy

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2 Comments

AlphaRL Over a year ago

It works.Thanks! Could you please explain one more thing: why does it work in my local environment?

Charles Duffy Over a year ago

In your local environment, there's no ~ in your PYTHONPATH.

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