Properly doing relative imports in python

I always have the same problem and I finally want to get rid of it. My folder structure looks like this

project
├── scipts
│   └── folder
│       └── file.py
└── submodules
    └── lab_devices
        └── optical_devices
            └── __init__.py
            └── powermeter_driver.py

I now want to include the powermeter_driver.py in file.py. So what I do in the file.py is:

from submodules.lab_devices.optical_devices.powermeter_driver import PowermeterDriver

but this gives ModuleNotFoundError: No module named 'submodules'. I don't want to use

import sys
sys.path.insert(0, '../submodules')

Is there an easy workaround?

Solution

The imports will be resolved correctly if you run the script in the correct way, which is from the parent directory and using the -m switch. So you should cd in the parent folder, add __init__.py files as in:

project
├── scripts
    └── __init__.py
│   └── folder
        └── __init__.py
│       └── file.py
└── submodules
    └── __init__.py
    └── lab_devices
        └── __init__.py
        └── optical_devices
            └── __init__.py
            └── powermeter_driver.py

so that python knows these are packages then run

python -m scripts.folder.file # note no .py

In file.py you can then use the absolute import as you are cause submodules will be detected as a package. You should indeed avoid hacking the sys.path by all means.