autoflake

Introduction

autoflake removes unused imports and unused variables from Python code. It makes use of pyflakes to do this.

By default, autoflake only removes unused imports for modules that are part of the standard library. (Other modules may have side effects that make them unsafe to remove automatically.) Removal of unused variables is also disabled by default.

autoflake also removes useless pass statements.

Example

Running autoflake on the below example:

$ autoflake --in-place --remove-unused-variables example.py

import math
import re
import os
import random
import multiprocessing
import grp, pwd, platform
import subprocess, sys


def foo():
    from abc import ABCMeta, WeakSet
    try:
        import multiprocessing
        print(multiprocessing.cpu_count())
    except ImportError as exception:
        print(sys.version)
    return math.pi

results in

import math
import sys


def foo():
    try:
        import multiprocessing
        print(multiprocessing.cpu_count())
    except ImportError:
        print(sys.version)
    return math.pi

Installation

$ pip install --upgrade autoflake

Advanced usage

To allow autoflake to remove additional unused imports (other than than those from the standard library), use the --imports option. It accepts a comma-separated list of names:

$ autoflake --imports=django,requests,urllib3 <filename>

To remove all unused imports (whether or not they are from the standard library), use the --remove-all-unused-imports option.

To remove unused variables, use the --remove-unused-variables option.

Below is the full listing of options:

usage: autoflake [-h] [-i] [-r] [--exclude globs] [--imports IMPORTS]
                 [--expand-star-imports] [--remove-all-unused-imports]
                 [--remove-duplicate-keys] [--remove-unused-variables]
                 [--version]
                 files [files ...]

Removes unused imports and unused variables as reported by pyflakes.

positional arguments:
  files                 files to format

optional arguments:
  -h, --help            show this help message and exit
  -c, --check           return error code if changes are needed
  -i, --in-place        make changes to files instead of printing diffs
  -r, --recursive       drill down directories recursively
  --exclude globs       exclude file/directory names that match these comma-
                        separated globs
  --imports IMPORTS     by default, only unused standard library imports are
                        removed; specify a comma-separated list of additional
                        modules/packages
  --expand-star-imports
                        expand wildcard star imports with undefined names;
                        this only triggers if there is only one star import in
                        the file; this is skipped if there are any uses of
                        `__all__` or `del` in the file
  --remove-all-unused-imports
                        remove all unused imports (not just those from the
                        standard library)
  --remove-duplicate-keys
                        remove all duplicate keys in objects
  --remove-unused-variables
                        remove unused variables
  --version             show program's version number and exit

Tests

To run the unit tests:

$ ./test_autoflake.py

There is also a fuzz test, which runs against any collection of given Python files. It tests autoflake against the files and checks how well it does by running pyflakes on the file before and after. The test fails if the pyflakes results change for the worse. (This is done in memory. The actual files are left untouched.):

$ ./test_fuzz.py --verbose

Excluding specific lines

It might be the case that you have some imports for their side effects, even if you are not using them directly in that file.

That is common, for example, in Flask based applications. In where you import Python modules (files) that imported a main app, to have them included in the routes.

For example:

from .endpoints import role, token, user, utils

As those imports are not being used directly, if you are using the option --remove-all-unused-imports, they would be removed.

To prevent that, without having to exclude the entire file, you can add a # noqa comment at the end of the line, like:

from .endpoints import role, token, user, utils  # noqa

That line will instruct autoflake to let that specific line as is.