coding style - What's the correct way to sort Python `import x` and `from x import y` statements?

Question

The python style guide suggests to group imports like this:

Imports should be grouped in the following order:

1. standard library imports
2. related third party imports
3. local application/library specific imports

However, it does not mention anything how the two different ways of imports should be laid out:

from foo import bar
import foo

There are multiple ways to sort them (let's assume all those import belong to the same group):

• first from..import, then import

  from g import gg
  from x import xx
  import abc
  import def
  import x
  

• first import, then from..import

  import abc
  import def
  import x
  from g import gg
  from x import xx
  

• alphabetic order by module name, ignoring the kind of import

  import abc
  import def
  from g import gg
  import x
  from xx import xx
  

PEP8 does not mention the preferred order for this and the "cleanup imports" features some IDEs have probably just do whatever the developer of that feature preferred.

I'm looking for another PEP clarifying this or a relevant comment/email from the BDFL (or another Python core developer). Please don't post subjective answers stating your own preference.

Answer 1

Imports are generally sorted alphabetically and described in various places besides PEP 8.

Alphabetically sorted modules are quicker to read and searchable. After all, Python is all about readability. Also, it is easier to verify that something is imported, and avoids duplicate imports.

There is nothing available in PEP 8 regarding sorting. So it's all about choosing what you use.

According to few references from reputable sites and repositories, also popularity, Alphabetical ordering is the way.

for e.g. like this:

import httplib
import logging
import random
import StringIO
import time
import unittest
from nova.api import openstack
from nova.auth import users
from nova.endpoint import cloud

OR

import a_standard
import b_standard

import a_third_party
import b_third_party

from a_soc import f
from a_soc import g
from b_soc import d

Reddit official repository also states that In general PEP-8 import ordering should be used. However, there are a few additions which are that for each imported group the order of imports should be:

import <package>.<module> style lines in alphabetical order
from <package>.<module> import <symbol> style in alphabetical order

References:

• https://code.google.com/p/soc/wiki/PythonStyleGuide
• https://github.com/reddit/reddit/wiki/PythonImportGuidelines
• http://docs.openstack.org/developer/hacking/
• http://developer.plone.org/reference_manuals/external/plone.api/contribute/conventions.html#grouping-and-sorting

PS: the isort utility automatically sorts your imports.