From ceec953cf6d8d7f4eb61b0c17475373369730fc4 Mon Sep 17 00:00:00 2001 From: Raymond Hettinger Date: Tue, 24 Nov 2020 11:00:00 -0800 Subject: [PATCH 1/3] Improve random_product() and random_permutation() --- Doc/library/itertools.rst | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/Doc/library/itertools.rst b/Doc/library/itertools.rst index 107bc515a677856..065c9bb6e4008f6 100644 --- a/Doc/library/itertools.rst +++ b/Doc/library/itertools.rst @@ -881,7 +881,7 @@ which incur interpreter overhead. def random_product(*args, repeat=1): "Random selection from itertools.product(*args, **kwds)" pools = [tuple(pool) for pool in args] * repeat - return tuple(random.choice(pool) for pool in pools) + return tuple(map(random.choice, pools)) def random_permutation(iterable, r=None): "Random selection from itertools.permutations(iterable, r)" @@ -900,7 +900,7 @@ which incur interpreter overhead. "Random selection from itertools.combinations_with_replacement(iterable, r)" pool = tuple(iterable) n = len(pool) - indices = sorted(random.randrange(n) for i in range(r)) + indices = sorted(random.choices(range(n), k=r)) return tuple(pool[i] for i in indices) def nth_combination(iterable, r, index): From f43c7aa54ad4ed1537d2a9efce5ac3cc70c8e666 Mon Sep 17 00:00:00 2001 From: Raymond Hettinger Date: Tue, 24 Nov 2020 11:07:37 -0800 Subject: [PATCH 2/3] Consistent choice of quotation marks --- Doc/library/itertools.rst | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/Doc/library/itertools.rst b/Doc/library/itertools.rst index 065c9bb6e4008f6..3de66c934928157 100644 --- a/Doc/library/itertools.rst +++ b/Doc/library/itertools.rst @@ -755,7 +755,7 @@ which incur interpreter overhead. "Count how many times the predicate is true" return sum(map(pred, iterable)) - def padnone(iterable): + def pad_none(iterable): """Returns the sequence elements and then returns None indefinitely. Useful for emulating the behavior of the built-in map() function. @@ -809,7 +809,7 @@ which incur interpreter overhead. nexts = cycle(islice(nexts, num_active)) def partition(pred, iterable): - 'Use a predicate to partition entries into false entries and true entries' + "Use a predicate to partition entries into false entries and true entries" # partition(is_odd, range(10)) --> 0 2 4 6 8 and 1 3 5 7 9 t1, t2 = tee(iterable) return filterfalse(pred, t1), filter(pred, t2) @@ -904,7 +904,7 @@ which incur interpreter overhead. return tuple(pool[i] for i in indices) def nth_combination(iterable, r, index): - 'Equivalent to list(combinations(iterable, r))[index]' + "Equivalent to list(combinations(iterable, r))[index]" pool = tuple(iterable) n = len(pool) if r < 0 or r > n: From 09de2c2f64c6b29fc8b5dd32305506ab98a96098 Mon Sep 17 00:00:00 2001 From: Raymond Hettinger Date: Sun, 29 Nov 2020 04:00:22 -0800 Subject: [PATCH 3/3] Update the tests to match the new name for pad_none --- Lib/test/test_itertools.py | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/Lib/test/test_itertools.py b/Lib/test/test_itertools.py index eaa6197bec395c6..702cf0820316b19 100644 --- a/Lib/test/test_itertools.py +++ b/Lib/test/test_itertools.py @@ -2290,7 +2290,7 @@ def test_permutations_sizeof(self): ... "Count how many times the predicate is true" ... return sum(map(pred, iterable)) ->>> def padnone(iterable): +>>> def pad_none(iterable): ... "Returns the sequence elements and then returns None indefinitely" ... return chain(iterable, repeat(None)) @@ -2460,7 +2460,7 @@ def test_permutations_sizeof(self): >>> list(pairwise('a')) [] ->>> list(islice(padnone('abc'), 0, 6)) +>>> list(islice(pad_none('abc'), 0, 6)) ['a', 'b', 'c', None, None, None] >>> list(ncycles('abc', 3))