Import a file from a subdirectory?

Try import .lib.BoxTime. For more information read about relative import in PEP 328.

Does your lib directory contain a __init__.py file?

Python uses __init__.py to determine if a directory is a module.

• Create a subdirectory named lib.
• Create an empty file named lib__init__.py.

• In libBoxTime.py, write a function foo() like this:

  def foo():
      print "foo!"
  

• In your client code in the directory above lib, write:

  from lib import BoxTime
  BoxTime.foo()
  

• Run your client code. You will get:

  foo!
  

Much later — in linux, it would look like this:

% cd ~/tmp
% mkdir lib
% touch lib/__init__.py
% cat > lib/BoxTime.py << EOF
heredoc> def foo():
heredoc>     print "foo!"
heredoc> EOF
% tree lib
lib
├── BoxTime.py
└── __init__.py

0 directories, 2 files
% python 
Python 2.7.6 (default, Mar 22 2014, 22:59:56) 
[GCC 4.8.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from lib import BoxTime
>>> BoxTime.foo()
foo!

You can try inserting it in sys.path:

sys.path.insert(0, './lib')
import BoxTime

try this:

from lib import BoxTime

Full example included

This basically covers all cases (make sure you have __init__.py in relative/path/to/your/lib/folder):

import sys, os
sys.path.append(os.path.dirname(os.path.realpath(__file__)) + "/relative/path/to/your/lib/folder")
import someFileNameWhichIsInTheFolder
...
somefile.foo()

Example:

You have in your project folder:

/root/myproject/app.py

You have in another project folder:

/root/anotherproject/utils.py
/root/anotherproject/__init__.py

You want to use /root/anotherproject/utils.py and call foo function which is in it.

So you write in app.py:

import sys, os
sys.path.append(os.path.dirname(os.path.realpath(__file__)) + "/../anotherproject")
import utils

utils.foo()

Create an empty file __init__.py in subdirectory /lib.
And add at the begin of main code

from __future__ import absolute_import 

then

import lib.BoxTime as BT
...
BT.bt_function()

or better

from lib.BoxTime import bt_function
...
bt_function()

/project/tester.py

/project/lib/BoxTime.py

create blank file __init__.py down the line till you reach the file

/project/lib/somefolder/BoxTime.py

#lib — needs has two items one __init__.py and a directory named somefolder
#somefolder has two items boxtime.py and __init__.py

I am writing this down because everyone seems to suggest that you have to create a lib directory.

You don’t need to name your sub-directory lib. You can name it anything provided you put an __init__.py into it.

You can do that by entering the following command in a linux shell:

$ touch anything/__init__.py 

So now you have this structure:

$ ls anything/
__init__.py
mylib.py

$ ls
main.py

Then you can import mylib into main.py like this:

from anything import mylib 

mylib.myfun()

You can also import functions and classes like this:

from anything.mylib import MyClass
from anything.mylib import myfun

instance = MyClass()
result = myfun()

Any variable function or class you place inside __init__.py can also be accessed:

import anything

print(anything.myvar)

Or like this:

from anything import myvar

print(myvar)

Just an addition to these answers.

If you want to import all files from all subdirectories, you can add this to the root of your file.

import sys, os
sys.path.extend([f'./{name}' for name in os.listdir(".") if os.path.isdir(name)])

And then you can simply import files from the subdirectories just as if these files are inside the current directory.

Working example

If I have the following directory with subdirectories in my project…

.
├── a.py
├── b.py
├── c.py
├── subdirectory_a
│   ├── d.py
│   └── e.py
├── subdirectory_b
│   └── f.py
├── subdirectory_c
│   └── g.py
└── subdirectory_d
    └── h.py

I can put the following code inside my a.py file

import sys, os
sys.path.extend([f'./{name}' for name in os.listdir(".") if os.path.isdir(name)])

# And then you can import files just as if these files are inside the current directory

import b
import c
import d
import e
import f
import g
import h

In other words, this code will abstract from which directory the file is coming from.

For this folder hierarchy diagram example:

/project/tester.py    
/project/lib/BoxTime.py

1- Create a blank py file __init__.py inside lib folder

2- In the caller py file tester.py add theses code lines

import os, sys
sys.path.insert(0,'lib')# insert the folder lib in system path
from BoxTime import Function_name # from the py file import the needed function

Easy explanation can be found in here.

Notice: This is refered to as creating/importing modules in/from different folder.

Personel experience: I tried to create module from jupyter notebook, it did not not work (maybe I done it improperly using .ipynb), I needed to do it manually outside the juypyter notebook, or using other IDE (e.g. pycharm).