Import Python Files From Another Directory Python 3

Python_Import_Other_Directories.md

Import Python Files From Another Directory

I've come across various ways to include files from other directories in python. At this time, none of my python projects have ever scaled enough to warrant a nice directory structure but I find this information useful to know.

Module Search

The Python Docs 6.1.4 explain nicely what happens when you try to import a module.

When a module named spam is imported, the interpreter first searches for a built-in module with that name. If not found, it then searches for a file named spam.py in a list of directories given by the variable sys.path. sys.path is initialized from these locations:
- The directory containing the input script (or the current directory when no file is specified).
- PYTHONPATH (a list of directory names, with the same syntax as the shell variable PATH).
- The installation-dependent default.

Python searches various specific locations for the moduled named. Those locations are determined by the contents of sys.path.

Method One

Since Python will search sys.path when it reaches an import module instruction, we can include the path to that module in sys.path before calling the import. Given a folder structure like this

Main/
    Main.py
    Tanks/
        Tank.py

we can import Tank.py like this

import sys
sys.path.append("./Tanks")

import Tank

Method Two

This method is inspired by Section 6.4 of the Python docs. It states that the presence of an __init__.py file (may be empty) will cause python to treat the directory it is in as a Package. That means we will be able to import <directory> as a module.

Notice that one of the directories in sys.path by default is the directory that the python file launched from. We can use that information to interpret the line When importing the package, Python searches through the directories on sys.path looking for the package subdirectory. Thus, any folders with __init__.py under a directory in sys.path will be importable as a module. So, given

Main/
    Main.py
    Tanks/
        __init__.py
        Tank.py
        BlueTanks/
            __init__.py
            BlueTank.py

We can import Tank.py like <Directory(a.k.a "package")>.filename

import Tanks.Tank

And we can continue this pattern

    import Tanks.BlueTanks.BlueTank

thanks for the short and to the point explanation!

if my file is in directory siblings of dir Tank, how do I import Tank.py?

Main/
    Main.py
    Tanks/
        __init__.py
        Tank.py             <-- that is in here
        BlueTanks/
            __init__.py
            BlueTank.py
    Planes/
         Planes.py           <-- want to do stuff here

Here is my Problem I do everythin but not able to still import the module