Description

Use dict, list, and set comprehensions to improve the readability and performance of Python code.

% ruff check --select=C4,PERF401

rest_framework/schemas/coreapi.py:383:27: C419 Unnecessary list comprehension
rest_framework/utils/field_mapping.py:70:17: C405 Unnecessary `list` literal (rewrite as a `set` literal)
rest_framework/views.py:360:17: PERF401 Use a list comprehension to create a transformed list
tests/schemas/test_openapi.py:265:16: C414 Unnecessary `list` call within `sorted()`
tests/schemas/test_openapi.py:369:16: C414 Unnecessary `list` call within `sorted()`
tests/schemas/test_openapi.py:401:16: C414 Unnecessary `list` call within `sorted()`
tests/test_model_serializer.py:235:60: C408 Unnecessary `dict` call (rewrite as a literal)
tests/test_requests_client.py:58:25: C416 Unnecessary `dict` comprehension (rewrite using `dict()`)
tests/test_requests_client.py:65:25: C416 Unnecessary `dict` comprehension (rewrite using `dict()`)
tests/test_validators.py:118:13: C419 Unnecessary list comprehension
tests/test_validators.py:124:13: C419 Unnecessary list comprehension
tests/utils.py:30:20: C419 Unnecessary list comprehension

% ruff check --select=C4 --fix --unsafe-fixes

Found 11 errors (11 fixed, 0 remaining).

% ruff rule C414

unnecessary-double-cast-or-process (C414)

Derived from the flake8-comprehensions linter.

Fix is always available.

What it does

Checks for unnecessary list, reversed, set, sorted, and tuple
call within list, set, sorted, and tuple calls.

Why is this bad?

It's unnecessary to double-cast or double-process iterables by wrapping
the listed functions within an additional list, set, sorted, or
tuple call. Doing so is redundant and can be confusing for readers.

Examples

list(tuple(iterable))

Use instead:

list(iterable)

This rule applies to a variety of functions, including list, reversed,
set, sorted, and tuple. For example:

• Instead of list(list(iterable)), use list(iterable).
• Instead of list(tuple(iterable)), use list(iterable).
• Instead of tuple(list(iterable)), use tuple(iterable).
• Instead of tuple(tuple(iterable)), use tuple(iterable).
• Instead of set(set(iterable)), use set(iterable).
• Instead of set(list(iterable)), use set(iterable).
• Instead of set(tuple(iterable)), use set(iterable).
• Instead of set(sorted(iterable)), use set(iterable).
• Instead of set(reversed(iterable)), use set(iterable).
• Instead of sorted(list(iterable)), use sorted(iterable).
• Instead of sorted(tuple(iterable)), use sorted(iterable).
• Instead of sorted(sorted(iterable)), use sorted(iterable).
• Instead of sorted(reversed(iterable)), use sorted(iterable).

Fix safety

This rule's fix is marked as unsafe, as it may occasionally drop comments
when rewriting the call. In most cases, though, comments will be preserved.