Why ModuleNotFound when importing a module in a same directory?

Question

Question

When I try to activate main.py on linux bash with the command as follows,

python3 main.py

The error message looking as below keeps appearing, and I cannot figure out why!!

File "main.py", line 1, in <module> import folder_beta.util_one File "folder_beta/util_one.py", line 1, in <module> ModuleNotFoundError: No module named 'util_two'

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The folder tree looks like as below:

folder_alpha ├── main.py └── folder_beta ├── __init__.py (empty) ├── util_one.py └── util_two.py

main.py

import folder_beta.util_one import folder_beta.util_two ....

util_one.py

import util_two ...

When I executed the 'util_one.py' alone, it works perfectly fine but when I executed the main.py, the error keeps appearing.

Can anyone tell me how to fix this problem, please?

Does this answer your question? Import a module from both within same package and from outside the package in Python 3 — MisterMiyagi
– MisterMiyagi, Commented Jan 28, 2020 at 17:30
When you run main.py, your package root path is folder_alpha. When util_one.py try to import util_two.py, it is trying to find util_two in folder_alpha path. Since it doesn't exist, Python returns a ModuleNotFoundError. — r.ook
– r.ook, Commented Jan 28, 2020 at 17:42

wim · Accepted Answer · 2024-09-09 18:38:28Z

2

That is an implicit relative import, it would have worked in Python 2 but it's no longer allowed in Python 3. From PEP 8:

Implicit relative imports should never be used and have been removed in Python 3.

In util_one.py module, change it to:

from folder_beta import util_two

Explicit relative imports are also possible here, the equivalent would be:

from . import util_two

edited Sep 9, 2024 at 18:38

answered Jan 28, 2020 at 17:31

wim

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5 Comments

Eiffelbear Over a year ago

Should we write down "from folder_beta" even though util_one.py and util_two.py are in the same folder?

r.ook Over a year ago

You can use explicit relative import as well, from . import util_two

r.ook Over a year ago

@Eiffelbear You should consider your project structure when building the inner modules. The modules will all use the project root as path.

Eiffelbear Over a year ago

@r.ook So the . in from . import util_two tells util_one.py to look up the util_two.py in the same directory, folder_beta, rather than upper directory, folder_alpha!

r.ook Over a year ago

That's correct. This might be a good reading for you: stackoverflow.com/questions/14132789/…

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