From 67c19e57b5c928278ebd191a545979ce786f06b3 Mon Sep 17 00:00:00 2001 From: Raymond Hettinger Date: Wed, 28 Feb 2024 17:04:56 -0600 Subject: Improve all_equal() recipe (gh-116081) Replace conjuction of next() calls with simpler len()/take() logic. Add key function. --- Doc/library/itertools.rst | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/Doc/library/itertools.rst b/Doc/library/itertools.rst index 42e7040..4e731fe 100644 --- a/Doc/library/itertools.rst +++ b/Doc/library/itertools.rst @@ -863,10 +863,9 @@ which incur interpreter overhead. "Given a predicate that returns True or False, count the True results." return sum(map(pred, iterable)) - def all_equal(iterable): + def all_equal(iterable, key=None): "Returns True if all the elements are equal to each other." - g = groupby(iterable) - return next(g, True) and not next(g, False) + return len(take(2, groupby(iterable, key))) <= 1 def first_true(iterable, default=False, pred=None): """Returns the first true value in the iterable. @@ -1225,6 +1224,8 @@ The following recipes have a more mathematical flavor: >>> [all_equal(s) for s in ('', 'A', 'AAAA', 'AAAB', 'AAABA')] [True, True, True, False, False] + >>> [all_equal(s, key=str.casefold) for s in ('', 'A', 'AaAa', 'AAAB', 'AAABA')] + [True, True, True, False, False] >>> quantify(range(99), lambda x: x%2==0) 50 -- cgit v0.12