How to fix "ImportError: No module named ..." error in Python?

Question

What is the correct way to fix this ImportError error?

I have the following directory structure:

/home/bodacydo
/home/bodacydo/work
/home/bodacydo/work/project
/home/bodacydo/work/project/programs
/home/bodacydo/work/project/foo

And I am in the directory

/home/bodacydo/work/project

Now if I type

python ./programs/my_python_program.py

I instantly get

ImportError: No module named foo.tasks

The ./programs/my_python_program.py contains the following line:

from foo.tasks import my_function

I can't understand why python won't find ./foo/tasks.py - it's there.

If I do it from the Python shell, then it works:

python
>>> from foo.tasks import my_function

It only doesn't work if I call it via python ./programs/my_python_program.py script.

score 149 · Accepted Answer · answered Feb 24 '10 at 12:47

149

Python does not add the current directory to sys.path, but rather the directory that the script is in. Add /home/bodacydo/work/project to either sys.path or $PYTHONPATH.

answered Feb 24 '10 at 12:47

Ignacio Vazquez-Abrams

776,304
153
1,341
1,358

11

So whats the point then of having __init__.py in the root folder? It seems to serve no purpose if you edit either sys.path or the pythonpath. – Jan 04 '14 at 23:13
12

@Editor: `__init__.py` only indicates that the directory should be treated as a package, when its parent is either in `sys.path` or is itself a package. – Ignacio Vazquez-Abrams Jan 04 '14 at 23:15
5

In addition check the permissions on the folder. That was the problem in my case. – SidJ Aug 24 '16 at 03:08
tried both still not working, I am using python 2.7 on macOs Sierra(10.12). – ishandutta2007 Jan 10 '17 at 04:39
24

To add current dir to python path, use `export PYTHONPATH=\`pwd\`` – rodorgas May 02 '17 at 21:39
3

What worked for me was to add to $PYTHONPATH the parent directory of the project, in your case will be: `/home/bodacydo/work` ... [see this answer](https://stackoverflow.com/a/714070/3404438) – maledr53 Jun 03 '17 at 22:22

score 38 · Answer 2 · answered Feb 24 '10 at 13:00

38

Do you have a file called __init__.py in the foo directory? If not then python won't recognise foo as a python package.

See the section on packages in the python tutorial for more information.

answered Feb 24 '10 at 13:00

Dave Kirby

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Thanks and yes, I had `__init__.py`. The problem this time was with `$PYTHONPATH`. Ignacio's solution worked. – bodacydo Feb 24 '10 at 13:08
2

The __init__.py files are required to make Python treat the directories as containing packages; this is done to prevent directories with a common name, such as string, from unintentionally hiding valid modules that occur later on the module search path. In the simplest case, __init__.py can just be an empty file – panofish Jan 14 '16 at 21:13
Thanks for saving me sometime. – timon_the_destroyer Mar 31 '17 at 13:24

score 11 · Answer 3 · answered Jul 17 '17 at 16:39

A better fix than setting PYTHONPATH is to use python -m module.path

This will correctly set sys.path[0] and is a more reliable way to execute modules.

I have a quick writeup about this problem, as other answerers have mentioned the reason for this is python path/to/file.py puts path/to on the beginning of the PYTHONPATH (sys.path).

score 9 · Answer 4 · answered Oct 25 '11 at 07:38

Here is a step-by-step solution:

Add a script called run.py in /home/bodacydo/work/project and edit it like this:
```
import programs.my_python_program
programs.my_python_program.main()
```
(replace main() with your equivalent method in my_python_program.)
Go to /home/bodacydo/work/project
Run run.py

Explanation: Since python appends to PYTHONPATH the path of the script from which it runs, running run.py will append /home/bodacydo/work/project. And voilà, import foo.tasks will be found.

score 8 · Answer 5 · answered Aug 01 '14 at 10:20

Example solution for adding the library to your PYTHONPATH.

Add the following line into your ~/.bashrc or just run it directly:
```
export PYTHONPATH="$PYTHONPATH:$HOME/.python"
```
Then link your required library into your ~/.python folder, e.g.
```
ln -s /home/user/work/project/foo ~/.python/
```

score 2 · Answer 6 · edited Jul 22 '14 at 08:06

In my mind I have to consider that the foo folder is a stand-alone library. I might want to consider moving it to the Lib\site-packages folder within a python installation. I might want to consider adding a foo.pth file there.

I know it's a library since the ./programs/my_python_program.py contains the following line:

from foo.tasks import my_function

So it doesn't matter that ./programs is a sibling folder to ./foo. It's the fact that my_python_program.py is run as a script like this:

python ./programs/my_python_program.py

score 1 · Answer 7 · answered Nov 22 '19 at 09:30

If you have this problem when using an instaled version, when using setup.py, make sure your module is included inside packages

setup(name='Your program',
    version='0.7.0',
    description='Your desccription',
    packages=['foo', 'foo.bar'], # add `foo.bar` here

How to fix "ImportError: No module named ..." error in Python?

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