https://github.com/python/cpython/commit/67c19e57b5c928278ebd191a545979ce786f06b3
commit: 67c19e57b5c928278ebd191a545979ce786f06b3
branch: main
author: Raymond Hettinger <[email protected]>
committer: rhettinger <[email protected]>
date: 2024-02-28T17:04:56-06:00
summary:
Improve all_equal() recipe (gh-116081)
Replace conjuction of next() calls with simpler len()/take() logic. Add key
function.
files:
M Doc/library/itertools.rst
diff --git a/Doc/library/itertools.rst b/Doc/library/itertools.rst
index 42e70404b306b0..4e731fefe8908d 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
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