Import Script from a Parent Directory

问题:

How do I import a module(python file) that resides in the parent directory?

Both directories have a __init__.py file in them but I still cannot import a file from the parent directory?

In this folder layout, Script B is attempting to import Script A:

Folder A:
   __init__.py
   Script A:
   Folder B:
     __init__.py
     Script B(attempting to import Script A)

The following code in Script B doesn't work:

import ../scriptA.py # I get a compile error saying the "." is invalid

回答1:

You don't import scripts in Python you import modules. Some python modules are also scripts that you can run directly (they do some useful work at a module-level).

In general it is preferable to use absolute imports rather than relative imports.

toplevel_package/
├── __init__.py
├── moduleA.py
└── subpackage
    ├── __init__.py
    └── moduleB.py

In moduleB:

from toplevel_package import moduleA

If you'd like to run moduleB.py as a script then make sure that parent directory for toplevel_package is in your sys.path.

回答2:

From the docs:

from .. import scriptA

You can do this in packages, but not in scripts you run directly. From the link above:

Note that both explicit and implicit relative imports are based on the name of the current module. Since the name of the main module is always "__main__", modules intended for use as the main module of a Python application should always use absolute imports.

If you create a script that imports A.B.B, you won't receive the ValueError.

回答3:

If you want to run the script directly, you can:

1. Add the FolderA's path to the environment variable (PYTHONPATH).
2. Add the path to sys.path in the your script.

Then:

import module_you_wanted