207

I'm having a hard time understanding how module importing works in Python (I've never done it in any other language before either).

Let's say I have:

myapp/__init__.py
myapp/myapp/myapp.py
myapp/myapp/SomeObject.py
myapp/tests/TestCase.py

Now I'm trying to get something like this:

myapp.py
===================
from myapp import SomeObject
# stuff ...

TestCase.py
===================
from myapp import SomeObject
# some tests on SomeObject

However, I'm definitely doing something wrong as Python can't see that myapp is a module:

ImportError: No module named myapp
Improve this question
1

15 Answers 15

Reset to default
142

In your particular case it looks like you're trying to import SomeObject from the myapp.py and TestCase.py scripts. From myapp.py, do

import SomeObject

since it is in the same folder. For TestCase.py, do

from ..myapp import SomeObject

However, this will work only if you are importing TestCase from the package. If you want to directly run python TestCase.py, you would have to mess with your path. This can be done within Python:

import sys
sys.path.append("..")
from myapp import SomeObject

though that is generally not recommended.

In general, if you want other people to use your Python package, you should use distutils to create a setup script. That way, anyone can install your package easily using a command like python setup.py install and it will be available everywhere on their machine. If you're serious about the package, you could even add it to the Python Package Index, PyPI.

Improve this answer
6
  • I tried simply using import in my TestCase.py but it still gave me the same error. I'm assuming it's because its in a sub-directory of the __init__.py?
    – user623990
    Commented Feb 21, 2012 at 18:49
  • Oh wait I think I get it. If my test cases are calling from the package, I'll be able to use the from ... import ... right?
    – user623990
    Commented Feb 21, 2012 at 18:52
  • 1
    You will only if TestCase is being imported from outside the package- for example, if I run from myapp.tests import TestCase from a script outside myapp. If you're running python TestCase.py` within the tests folder you can't do relative imports
    – David Robinson
    Commented Feb 21, 2012 at 19:00
  • 2
    I ran "pip install -e . " to install myapp, but when trying to run TestCase in visual studio code I still get "ImportError: No module named myapp". but if I run "python" and then in python run "from myapp import SomeObject" it works. What am I doing wrong?
    – dagrun
    Commented Apr 9, 2019 at 8:19
  • @DavidRobinson I used the method you have mentioned, that showed no error after executing from fodername import file_name_of_my_py_code, but when I tried to access the object defined in file_name_of_my_py_code.py it says NameError: name 'ClassName' is not defined
    – Kavin Raju S
    Commented May 2, 2020 at 2:02
56

The function import looks for files into your PYTHONPATH env. variable and your local directory. So you can either put all your files in the same directory, or export the path typing into a terminal::

export PYTHONPATH="$PYTHONPATH:/path_to_myapp/myapp/myapp/"
Improve this answer
4
  • 3
    Then how can I make sure it works for everyone else who would use it? I'd rather not have to tell them to set certain environment variables before running it.
    – user623990
    Commented Feb 21, 2012 at 18:34
  • 1
    the current directory is in pythonpath, so as long as the scripts are in the same folder/directory it should work. unfortunately each of these scripts are in separate directories.
    – JKirchartz
    Commented Feb 21, 2012 at 18:47
  • 5
    For Windows users, instead of export we have "set PYTHONPATH=%PYTHONPATH%;C:\path_to_myapp\myapp\myapp\"
    – loved.by.Jesus
    Commented Sep 2, 2016 at 14:54
  • In vs code I was able to fix this by adding PYTHONPATH Env variable to my launch.json:"env": { "PYTHONPATH": "${workspaceFolder}" }
    – Michael Armitage
    Commented Dec 18, 2018 at 13:47
15

You can try

from myapp.myapp import SomeObject

because your project name is the same as the myapp.py which makes it search the project document first

Improve this answer
14

exporting path is a good way. Another way is to add a .pth to your site-packages location. On my mac my python keeps site-packages in /Library/Python shown below

/Library/Python/2.7/site-packages

I created a file called awesome.pth at /Library/Python/2.7/site-packages/awesome.pth and in the file put the following path that references my awesome modules

/opt/awesome/custom_python_modules
Improve this answer
4
  • 1
    in the case i am working in windows how do i do that
    – Nwawel A Iroume
    Commented Feb 10, 2016 at 16:50
  • I'm not sure. In the case that you are using windows. Find some vm software and use linux. Or - see this answer on exporting variables in windows. stackoverflow.com/questions/559816/…
    – jmontross
    Commented Mar 8, 2016 at 22:45
  • this is exactly what i needed
    – Lee88
    Commented Jan 27, 2017 at 12:30
  • 1
    Happy to hear that @Lee88 - took me a while to figure it out myself :)
    – jmontross
    Commented Sep 3, 2017 at 4:35
12

You need to have 

__init__.py

in all the folders that have code you need to interact with. You also need to specify the top folder name of your project in every import even if the file you tried to import is at the same level.

Improve this answer
0
6

In your first myapp directory ,u can add a setup.py file and add two python code in setup.py

from setuptools import setup
setup(name='myapp')

in your first myapp directory in commandline , use pip install -e . to install the package

Improve this answer
3

pip install on Windows 10 defaults to installing in 'Program Files/PythonXX/Lib/site-packages' which is a directory that requires administrative privileges. So I fixed my issue by running pip install as Administrator (you have to open command prompt as administrator even if you are logged in with an admin account). Also, it is safer to call pip from python.
e.g.
python -m pip install <package-name>
instead of
pip install <package-name>

Improve this answer
1
  • you made my day. To others .. this is important if you have lot of local modules. Local module is used by other local module you need to install your local module first and make it part of your import list for other module. Easy but took long time for me to grasp the module concept.
    – One
    Commented Jan 14, 2021 at 4:55
2

let's say i write a module

import os
my_home_dir=os.environ['HOME'] // in windows 'HOMEPATH'
file_abs_path=os.path.join(my_home_dir,"my_module.py")

with open(file_abs_path,"w") as f:
   f.write("print('I am loaded successfully')")

import importlib
importlib.util.find_spec('my_module') ==> cannot find

we have to tell python where to look for the module. we have to add our path to the sys.path

 import sys
 sys.path.append(file_abs_path)

now importlib.util.find_spec('my_module') returns:

  ModuleSpec(name='my_module', loader=<_frozen_importlib_external.SourceFileLoader object at 0x7fa40143e8e0>, origin='/Users/name/my_module.py')

we created our module, we informed python its path, now we should be able to import it

 import my_module

//I am loaded successfully
Improve this answer
0
2

Short Answer:

python -m ParentPackage.Submodule

Executing the required file via module flag worked for me. Lets say we got a typical directory structure as below:

my_project:
 | Core
    ->myScript.py
 | Utils
   ->helpers.py
 configs.py

Now if you want to run a file inside a directory, that has imports from other modules, all you need to do is like below:

python -m Core.myscript

PS: You gotta use dot notation to refer the submodules(Files/scripts you want to execute). Also I used python3.9+. So I didnt require neither any init.py nor any sys path append statements.

Hope that helps! Happy Coding!

Improve this answer
0

In my case it was Windows vs Python surprise, despite Windows filenames are not case sensitive, Python import is. So if you have Stuff.py file you need to import this name as-is.

Improve this answer
0

This worked for me:

from .myapp import SomeObject

The . signifies that it will search any local modules from the parent module.

Improve this answer
0

If you are using the IPython Console, make sure your IDE (e.g., spyder) is pointing to the right working directory (i.e., your project folder)

Improve this answer
0

Besides the suggested solutions like the accepted answer, I had the same problem in Pycharm, and I didn't want to modify imports like the relative addressing suggested above.

I finally found out that if I mark my src/ (root directory of my python codes) as the source in Interpreter settings, the issue will be resolved.

In the settings

enter image description here

Improve this answer
0

I added my custom modules path to python3*._pth file.It will be located in the python installed directory.

This resolved the issue

Improve this answer
-1

If you use Anaconda you can do:

conda develop /Path/To/Your/Modules

from the Shell and it will write your path into a conda.pth file into the standard directory for 3rd party modules (site-packages in my case).

Improve this answer