From b67273842a23abd7937a684245eef3a2a3b35396 Mon Sep 17 00:00:00 2001 From: Raymond Hettinger Date: Thu, 14 Dec 2023 17:27:39 -0600 Subject: [PATCH] Optimize unique_justseen() recipe for a common case. (gh-113147) (cherry picked from commit 5f7d7353b47ccf634b9b65f933d3fdeeb395301f) Co-authored-by: Raymond Hettinger --- Doc/library/itertools.rst | 2 ++ 1 file changed, 2 insertions(+) diff --git a/Doc/library/itertools.rst b/Doc/library/itertools.rst index d79f40cd05e8f4..15b449d650512a 100644 --- a/Doc/library/itertools.rst +++ b/Doc/library/itertools.rst @@ -1016,6 +1016,8 @@ which incur interpreter overhead. "List unique elements, preserving order. Remember only the element just seen." # unique_justseen('AAAABBBCCDAABBB') --> A B C D A B # unique_justseen('ABBcCAD', str.lower) --> A B c A D + if key is None: + return map(operator.itemgetter(0), groupby(iterable)) return map(next, map(operator.itemgetter(1), groupby(iterable, key)))