How to do relative imports in Python?

Question

Imagine this directory structure:

app/
   __init__.py
   sub1/
      __init__.py
      mod1.py
   sub2/
      __init__.py
      mod2.py

I\'

Answer 1

main.py
setup.py
app/ ->
    __init__.py
    package_a/ ->
       __init__.py
       module_a.py
    package_b/ ->
       __init__.py
       module_b.py

1. You run python main.py.
2. main.py does: import app.package_a.module_a
3. module_a.py does import app.package_b.module_b

Alternatively 2 or 3 could use: from app.package_a import module_a

That will work as long as you have app in your PYTHONPATH. main.py could be anywhere then.

So you write a setup.py to copy (install) the whole app package and subpackages to the target system's python folders, and main.py to target system's script folders.