Skip to content

unnecessary-generator-set (C401)#

Derived from the flake8-comprehensions linter.

Fix is always available.

What it does#

Checks for unnecessary generators that can be rewritten as set comprehensions (or with set directly).

Why is this bad?#

It is unnecessary to use set around a generator expression, since there are equivalent comprehensions for these types. Using a comprehension is clearer and more idiomatic.

Further, if the comprehension can be removed entirely, as in the case of set(x for x in foo), it's better to use set(foo) directly, since it's even more direct.


set(f(x) for x in foo)
set(x for x in foo)

Use instead:

{f(x) for x in foo}

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.