How to import package modules from package's __init__.py?

Question

I have a list of module name what I want to import from __init__.py.

$ mkdir /tmp/pkg
$ touch /tmp/__init__.py /tmp/pkg/{a.py,b.py}
$ cat /tmp/pkg/__init__.py
to_import = ["a", "b"]
import importlib
for toi in to_import:
 importlib.import_module(toi)
$ cd /
$ python
>>> import tmp.pkg
Traceback (most recent call last):
 File "<stdin>", line 1, in <module>
 File "tmp/pkg/__init__.py", line 5, in <module>
 importlib.import_module(toi)
 File "/usr/lib/python2.7/importlib/__init__.py", line 37, in import_module
 __import__(name)
ImportError: No module named a
>>> 

python 2.7.4 Ubuntu 64-bit

Question: So how do I import package modules from package's __init__.py?

• tdelaney: Okay, I don't get it. Why not just do import a, b?
• Zaar Hai: I'm minimized the example for simplicity. The module list is dynamic and obtained elsewhere.

Answer 1

You can use relative imports for this. Try to change /tmp/pkg/__init__.py to the following:

to_import = [".a", ".b"]
import importlib
for toi in to_import:
 importlib.import_module(toi, __name__)

Notice dots before module names and second argument to import_module function.

• tdelaney: ...or just use a simple import statement as the language intends. This is a super complicated to do something easy.
• Kirill Spitsyn: ..but topic starter specifically asked about importing all modules from a list. Also, with import statement you nevertheless need to use relative imports in this scenario, like from . import a, b.
• tdelaney: import a,b is a list and its the normal way to import from a __init__.py file. You don't need "from ." or "." anything. "." is used for relative imports among package modules, but not __init__.py itself.
• Kirill Spitsyn: Indeed, import a, b works there. Few minor points: I believe that there are no difference between relative imports from __init__.py and from other package modules; in python 2.7 you can use for that both syntaxes: with or without a dot (unless there is from __future__ import absolute_import statement); and relative imports without a dot were deprecated in python 3.
• Zaar Hai: Simple and elegant. Thanks Kirill! I new I was close :)

Answer 2

You must add the init at the end

import tmp.pkg.__init__

The imports should be in the same path as the init.py file otherwise they will not work

FullPath/pkg/__init__.py

init.py file

to_import = ["__HistogramObjects__"]
import importlib
for toi in to_import:
 importlib.import_module(toi)

Then in your file that you want to import from

import FullPath.pkg.__init__ as im
for i in im.to_import:
 print i

Your output should be:

__HistogramObjects__