Python Relative Import From Parent Directories

Question

I've read many docs over the last few days about relative Python imports but run into a struggle with the following folder structure:

parent_folder
       ├── subfolder1
       │        └── __init__.py
       │        └── file_1.py
       ├── subfolder2
       │        └── __init__.py
       │        └── file_2.py
       │
       └ __init__.py (parent folder has an init in it)

In file_2.py I would like to access the functions in file_1.py. I've tried adding the following to file_2.py but none seem to work:

1. from ..subfolder1 import file_1    #ImportError: attempted relative import with no known parent package

2. import parent_folder.subfolder1.file_1    #ModuleNotFoundError: No module named 'parent_folder'

3. from parent_folder.subfolder1 import file_1    #ModuleNotFoundError: No module named 'parent_folder'

I'm really lost right now and can't seem to understand why this is occuring. I've probably read 10 different guides on relative imports now and still can't figure out why.

Note, if I put file_2.py inside parent_folder, and then add import subfolder1.file1 it imports well, but I can't move file_2.py from it's position or use sys.path.append()

Does anyone with more module experience than I have any insight? Thank you!

Answer 1

The answers advising messing with the sys path are wrong - unfortunately this advice is floating over the web causing infinite frustration and crashes (good) to subtle bugs (bad).

The correct answer is running your script using the -m switch from the parent folder of the top most package. So if this parent_folder is a package as it looks it is and you want to run file_1.py you should

$ python -m parent_folder.subfolder1.file_1

any of the three imports would work then