38

In Ruby, instead of repeating the "require" (the "import" in Python) word lots of times, I do

%w{lib1 lib2 lib3 lib4 lib5}.each { |x| require x }

So it iterates over the set of "libs" and "require" (import) each one of them. Now I'm writing a Python script and I would like to do something like that. Is there a way to, or do I need to write "import" for all of them.

The straight-forward "traduction" would be something like the following code. Anyway, since Python does not import libs named as strings, it does not work.

requirements = [lib1, lib2, lib3, lib4, lib5]
for lib in requirements:
    import lib

Thanks in advance

Ben Hare
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Eduardo
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    Python actually does have a built-in function [`__import__`](http://docs.python.org/library/functions.html#__import__) which you can use to import a module named in a string. But it's meant to be called from the implementation of the `import` statement, not from user code. It certainly wouldn't be the proper solution in this case. – David Z Jul 15 '10 at 22:38
  • Oh! Really thanks for all the answers. Very good all of them. – Eduardo Jul 15 '10 at 22:59

7 Answers7

69

For known module, just separate them by commas:

import lib1, lib2, lib3, lib4, lib5

If you really need to programmatically import based on dynamic variables, a literal translation of your ruby would be:

modnames = "lib1 lib2 lib3 lib4 lib5".split()
for lib in modnames:
    globals()[lib] = __import__(lib)

Though there's no need for this in your example.

MSeifert
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Brian
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    Please note that the first code snippet defies Pep 8's recommendations https://www.python.org/dev/peps/pep-0008/#imports – Minion Jim Jul 11 '19 at 10:20
28

Try this:

import lib1, lib2, lib3, lib4, lib5

You can also change the name they are imported under in this way, like so: 

import lib1 as l1, lib2 as l2, lib3, lib4 as l4, lib5
John Howard
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9

import lib1, lib2, lib3, lib4, lib5

ykaganovich
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9

if you want multi-line:

from englishapps.multiple.mainfile import (
    create_multiple_,
    get_data_for_multiple
)
Edgar Manukyan
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4

You can import from a string which contains your module name by using the __import__ function.

requirements = [lib1, lib2, lib3, lib4, lib5]
for lib in requirements:
    x = __import__(lib)
MSeifert
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txwikinger
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3

You can use __import__ if you have a list of strings that represent modules, but it's probably cleaner if you follow the hint in the documentation and use importlib.import_module directly:

import importlib
requirements = [lib1, lib2, lib3, lib4, lib5]
imported_libs = {lib: importlib.import_module(lib) for lib in requirements}

You don't have the imported libraries as variables available this way but you could access them through the imported_libs dictionary:

>>> requirements = ['sys', 'itertools', 'collections', 'pickle']
>>> imported_libs = {lib: importlib.import_module(lib) for lib in requirements}
>>> imported_libs
{'collections': <module 'collections' from 'lib\\collections\\__init__.py'>,
 'itertools': <module 'itertools' (built-in)>,
 'pickle': <module 'pickle' from 'lib\\pickle.py'>,
 'sys': <module 'sys' (built-in)>}

>>> imported_libs['sys'].hexversion
50660592

You could also update your globals and then use them like they were imported "normally":

>>> globals().update(imported_libs)
>>> sys
<module 'sys' (built-in)>
MSeifert
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2

I just learned from a coworker today that, according to the PEP 8 Style Guide, imports in Python should actually be written on separate lines:

import os
import sys

The style guide calls import sys, os wrong.

Dan Swain
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