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sorted-min-max (FURB192)

Preview (since v0.4.2) · Related issues · View source

Derived from the refurb linter.

Fix is sometimes available.

This rule is unstable and in preview. The --preview flag is required for use.

What it does

Checks for uses of sorted() to retrieve the minimum or maximum value in a sequence.

Why is this bad?

Using sorted() to compute the minimum or maximum value in a sequence is inefficient and less readable than using min() or max() directly.

Example

nums = [3, 1, 4, 1, 5]
lowest = sorted(nums)[0]
highest = sorted(nums)[-1]
highest = sorted(nums, reverse=True)[0]

Use instead:

nums = [3, 1, 4, 1, 5]
lowest = min(nums)
highest = max(nums)

Fix safety

In some cases, migrating to min or max can lead to a change in behavior, notably when breaking ties.

As an example, sorted(data, key=itemgetter(0), reverse=True)[0] will return the last "minimum" element in the list, if there are multiple elements with the same key. However, min(data, key=itemgetter(0)) will return the first "minimum" element in the list in the same scenario.

As such, this rule's fix is marked as unsafe when the reverse keyword is used.

References