Python – How to import the class within the same directory or sub directory

pythonpython-import

I have a directory that stores all the .py files.

bin/
   main.py
   user.py # where class User resides
   dir.py # where class Dir resides

I want to use classes from user.py and dir.py in main.py.
How can I import these Python classes into main.py?
Furthermore, how can I import class User if user.py is in a sub directory?

bin/
    dir.py
    main.py
    usr/
        user.py

Best Answer

Python 2

Make an empty file called __init__.py in the same directory as the files. That will signify to Python that it's "ok to import from this directory".

Then just do...

from user import User
from dir import Dir

The same holds true if the files are in a subdirectory - put an __init__.py in the subdirectory as well, and then use regular import statements, with dot notation. For each level of directory, you need to add to the import path.

bin/
    main.py
    classes/
        user.py
        dir.py

So if the directory was named "classes", then you'd do this:

from classes.user import User
from classes.dir import Dir

Python 3

Same as previous, but prefix the module name with a . if not using a subdirectory:

from .user import User
from .dir import Dir

Related Solutions

Python – How to import a module given the full path

For Python 3.5+ use:

import importlib.util
spec = importlib.util.spec_from_file_location("module.name", "/path/to/file.py")
foo = importlib.util.module_from_spec(spec)
spec.loader.exec_module(foo)
foo.MyClass()

For Python 3.3 and 3.4 use:

from importlib.machinery import SourceFileLoader

foo = SourceFileLoader("module.name", "/path/to/file.py").load_module()
foo.MyClass()

(Although this has been deprecated in Python 3.4.)

For Python 2 use:

import imp

foo = imp.load_source('module.name', '/path/to/file.py')
foo.MyClass()

There are equivalent convenience functions for compiled Python files and DLLs.

Python – How to do relative imports in Python

Everyone seems to want to tell you what you should be doing rather than just answering the question.

The problem is that you're running the module as '__main__' by passing the mod1.py as an argument to the interpreter.

From PEP 328:

Relative imports use a module's __name__ attribute to determine that module's position in the package hierarchy. If the module's name does not contain any package information (e.g. it is set to '__main__') then relative imports are resolved as if the module were a top level module, regardless of where the module is actually located on the file system.

In Python 2.6, they're adding the ability to reference modules relative to the main module. PEP 366 describes the change.

Update: According to Nick Coghlan, the recommended alternative is to run the module inside the package using the -m switch.