https://github.com/python/cpython/commit/ef24f552fbaf6f77d6d0d16eb145cb4a71236c7f
commit: ef24f552fbaf6f77d6d0d16eb145cb4a71236c7f
branch: 3.14
author: Miss Islington (bot) <[email protected]>
committer: rhettinger <[email protected]>
date: 2026-01-12T20:18:43Z
summary:
[3.14] Minor readability/usability improvement to the recipes section
(gh-143753) (gh-143755)
files:
M Doc/library/itertools.rst
diff --git a/Doc/library/itertools.rst b/Doc/library/itertools.rst
index e28d139c76e0c8..08dacb505f7748 100644
--- a/Doc/library/itertools.rst
+++ b/Doc/library/itertools.rst
@@ -819,7 +819,7 @@ well as with the built-in itertools such as ``map()``,
``filter()``,
A secondary purpose of the recipes is to serve as an incubator. The
``accumulate()``, ``compress()``, and ``pairwise()`` itertools started out as
-recipes. Currently, the ``sliding_window()``, ``iter_index()``, and
``sieve()``
+recipes. Currently, the ``sliding_window()``, ``derangements()``, and
``sieve()``
recipes are being tested to see whether they prove their worth.
Substantially all of these recipes and many, many others can be installed from
@@ -838,11 +838,16 @@ and :term:`generators <generator>` which incur
interpreter overhead.
.. testcode::
+ from itertools import (accumulate, batched, chain, combinations, compress,
+ count, cycle, filterfalse, groupby, islice, permutations, product,
+ repeat, starmap, tee, zip_longest)
from collections import Counter, deque
from contextlib import suppress
from functools import reduce
- from math import comb, prod, sumprod, isqrt
- from operator import is_not, itemgetter, getitem, mul, neg
+ from math import comb, isqrt, prod, sumprod
+ from operator import getitem, is_not, itemgetter, mul, neg
+
+ # ==== Basic one liners ====
def take(n, iterable):
"Return first n items of the iterable as a list."
@@ -899,8 +904,8 @@ and :term:`generators <generator>` which incur interpreter
overhead.
def first_true(iterable, default=False, predicate=None):
"Returns the first true value or the *default* if there is no true
value."
- # first_true([a,b,c], x) → a or b or c or x
- # first_true([a,b], x, f) → a if f(a) else b if f(b) else x
+ # first_true([a, b, c], x) → a or b or c or x
+ # first_true([a, b], x, f) → a if f(a) else b if f(b) else x
return next(filter(predicate, iterable), default)
def all_equal(iterable, key=None):
@@ -908,6 +913,8 @@ and :term:`generators <generator>` which incur interpreter
overhead.
# all_equal('4٤௪౪໔', key=int) → True
return len(take(2, groupby(iterable, key))) <= 1
+ # ==== Data pipelines ====
+
def unique_justseen(iterable, key=None):
"Yield unique elements, preserving order. Remember only the element
just seen."
# unique_justseen('AAAABBBCCDAABBB') → A B C D A B
@@ -940,7 +947,7 @@ and :term:`generators <generator>` which incur interpreter
overhead.
def sliding_window(iterable, n):
"Collect data into overlapping fixed-length chunks or blocks."
- # sliding_window('ABCDEFG', 4) → ABCD BCDE CDEF DEFG
+ # sliding_window('ABCDEFG', 3) → ABC BCD CDE DEF EFG
iterator = iter(iterable)
window = deque(islice(iterator, n - 1), maxlen=n)
for x in iterator:
@@ -949,7 +956,7 @@ and :term:`generators <generator>` which incur interpreter
overhead.
def grouper(iterable, n, *, incomplete='fill', fillvalue=None):
"Collect data into non-overlapping fixed-length chunks or blocks."
- # grouper('ABCDEFG', 3, fillvalue='x') → ABC DEF Gxx
+ # grouper('ABCDEFG', 3, fillvalue='x') → ABC DEF Gxx
# grouper('ABCDEFG', 3, incomplete='strict') → ABC DEF ValueError
# grouper('ABCDEFG', 3, incomplete='ignore') → ABC DEF
iterators = [iter(iterable)] * n
@@ -1014,10 +1021,7 @@ and :term:`generators <generator>` which incur
interpreter overhead.
while True:
yield function()
-
-The following recipes have a more mathematical flavor:
-
-.. testcode::
+ # ==== Mathematical operations ====
def multinomial(*counts):
"Number of distinct arrangements of a multiset."
@@ -1036,9 +1040,11 @@ The following recipes have a more mathematical flavor:
# sum_of_squares([10, 20, 30]) → 1400
return sumprod(*tee(iterable))
+ # ==== Matrix operations ====
+
def reshape(matrix, columns):
"Reshape a 2-D matrix to have a given number of columns."
- # reshape([(0, 1), (2, 3), (4, 5)], 3) → (0, 1, 2), (3, 4, 5)
+ # reshape([(0, 1), (2, 3), (4, 5)], 3) → (0, 1, 2) (3, 4, 5)
return batched(chain.from_iterable(matrix), columns, strict=True)
def transpose(matrix):
@@ -1048,10 +1054,12 @@ The following recipes have a more mathematical flavor:
def matmul(m1, m2):
"Multiply two matrices."
- # matmul([(7, 5), (3, 5)], [(2, 5), (7, 9)]) → (49, 80), (41, 60)
+ # matmul([(7, 5), (3, 5)], [(2, 5), (7, 9)]) → (49, 80) (41, 60)
n = len(m2[0])
return batched(starmap(sumprod, product(m1, transpose(m2))), n)
+ # ==== Polynomial arithmetic ====
+
def convolve(signal, kernel):
"""Discrete linear convolution of two iterables.
Equivalent to polynomial multiplication.
@@ -1106,6 +1114,8 @@ The following recipes have a more mathematical flavor:
powers = reversed(range(1, n))
return list(map(mul, coefficients, powers))
+ # ==== Number theory ====
+
def sieve(n):
"Primes less than n."
# sieve(30) → 2 3 5 7 11 13 17 19 23 29
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