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Simplify sieve() recipe. Add edge case tests. (GH-96892)

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Raymond Hettinger 2022-09-17 11:31:04 -05:00 committed by GitHub
parent 0587810698
commit 78359b1d45
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1 changed files with 7 additions and 1 deletions
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Doc/library/itertools.rst
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@ -818,7 +818,7 @@ which incur interpreter overhead.
data = bytearray([1]) * n
data[:2] = 0, 0
limit = math.isqrt(n) + 1
for p in compress(count(), islice(data, limit)):
for p in compress(range(limit), data):
data[p+p : n : p] = bytearray(len(range(p+p, n, p)))
return compress(count(), data)
@ -1168,6 +1168,9 @@ which incur interpreter overhead.
>>> list(sieve(30))
[2, 3, 5, 7, 11, 13, 17, 19, 23, 29]
>>> small_primes = [2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59]
>>> all(list(sieve(n)) == [p for p in small_primes if p < n] for n in range(60))
True
>>> len(list(sieve(100)))
25
>>> len(list(sieve(1_000)))
@ -1178,6 +1181,9 @@ which incur interpreter overhead.
9592
>>> len(list(sieve(1_000_000)))
78498
>>> carmichael = {561, 1105, 1729, 2465, 2821, 6601, 8911} # https://oeis.org/A002997
>>> set(sieve(10_000)).isdisjoint(carmichael)
True
>>> list(flatten([('a', 'b'), (), ('c', 'd', 'e'), ('f',), ('g', 'h', 'i')]))
['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i']