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bpo-39374: Updated sorting documentation (GH-18177)

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Juhana Jauhiainen 2020-01-26 00:18:58 +02:00 committed by Raymond Hettinger
parent 4b09dc79f4
commit 8271441d8b
1 changed files with 6 additions and 4 deletions
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Doc/howto/sorting.rst
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@ -43,16 +43,18 @@ Key Functions
============= =============
Both :meth:`list.sort` and :func:`sorted` have a *key* parameter to specify a Both :meth:`list.sort` and :func:`sorted` have a *key* parameter to specify a
function to be called on each list element prior to making comparisons. function (or other callable) to be called on each list element prior to making
comparisons.
For example, here's a case-insensitive string comparison: For example, here's a case-insensitive string comparison:
>>> sorted("This is a test string from Andrew".split(), key=str.lower) >>> sorted("This is a test string from Andrew".split(), key=str.lower)
['a', 'Andrew', 'from', 'is', 'string', 'test', 'This'] ['a', 'Andrew', 'from', 'is', 'string', 'test', 'This']
The value of the *key* parameter should be a function that takes a single argument The value of the *key* parameter should be a function (or other callable) that
and returns a key to use for sorting purposes. This technique is fast because takes a single argument and returns a key to use for sorting purposes. This
the key function is called exactly once for each input record. technique is fast because the key function is called exactly once for each
input record.
A common pattern is to sort complex objects using some of the object's indices A common pattern is to sort complex objects using some of the object's indices
as keys. For example: as keys. For example: