https://github.com/python/cpython/commit/1581c9d936a665dad9a5481ba880ac3b8fb2b824
commit: 1581c9d936a665dad9a5481ba880ac3b8fb2b824
branch: 3.12
author: Bénédikt Tran <[email protected]>
committer: rhettinger <[email protected]>
date: 2025-02-08T08:10:41-06:00
summary:
[3.12] Add multinomial to the itertools recipes docs (gh-129760) (gh-129854)
files:
M Doc/library/itertools.rst
diff --git a/Doc/library/itertools.rst b/Doc/library/itertools.rst
index a82fd8630b7b6a..b1b7b630a5ecbb 100644
--- a/Doc/library/itertools.rst
+++ b/Doc/library/itertools.rst
@@ -1082,6 +1082,12 @@ The following recipes have a more mathematical flavor:
n -= n // prime
return n
+ def multinomial(*counts):
+ "Number of distinct arrangements of a multiset."
+ # Counter('abracadabra').values() -> 5 2 1 1 2
+ # multinomial(5, 2, 1, 1, 2) → 83160
+ return math.prod(map(math.comb, accumulate(counts), counts))
+
.. doctest::
:hide:
@@ -1644,6 +1650,12 @@ The following recipes have a more mathematical flavor:
>>> ''.join(it)
'DEF1'
+ >>> multinomial(5, 2, 1, 1, 2)
+ 83160
+ >>> word = 'coffee'
+ >>> multinomial(*collections.Counter(word).values()) ==
len(set(permutations(word)))
+ True
+
.. testcode::
:hide:
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