Fix Python – import module from string variable

Question

Asked By – theta

I’m working on a documentation (personal) for nested matplotlib (MPL) library, which differs from MPL own provided, by interested submodule packages. I’m writing Python script which I hope will automate document generation from future MPL releases.
I selected interested submodules/packages and want to list their main classes from which I’ll generate list and process it with pydoc

Problem is that I can’t find a way to instruct Python to load submodule from string. Here is example of what I tried:

import matplotlib.text as text
x = dir(text)

.

i = __import__('matplotlib.text')
y = dir(i)

.

j = __import__('matplotlib')
z = dir(j)

And here is 3 way comparison of above lists through pprint:

enter image description here

I don’t understand what’s loaded in y object – it’s base matplotlib plus something else, but it lack information that I wanted and that is main classes from matplotlib.text package. It’s top blue coloured part on screenshot (x list)

Please don’t suggest Sphinx as different approach.

Now we will see solution for issue: import module from string variable


Answer

The __import__ function can be a bit hard to understand.

If you change

i = __import__('matplotlib.text')

to

i = __import__('matplotlib.text', fromlist=[''])

then i will refer to matplotlib.text.

In Python 2.7 and Python 3.1 or later, you can use importlib:

import importlib

i = importlib.import_module("matplotlib.text")

Some notes

  • If you’re trying to import something from a sub-folder e.g. ./feature/email.py, the code will look like importlib.import_module("feature.email")

  • You can’t import anything if there is no __init__.py in the folder with file you are trying to import

This question is answered By – mzjn

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