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| -rw-r--r-- | Doc/library/itertools.rst | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/Doc/library/itertools.rst b/Doc/library/itertools.rst index 4224371..3cfc260 100644 --- a/Doc/library/itertools.rst +++ b/Doc/library/itertools.rst @@ -1030,13 +1030,16 @@ The following recipes have a more mathematical flavor: def sieve(n): "Primes less than n." # sieve(30) --> 2 3 5 7 11 13 17 19 23 29 + if n > 2: + yield 2 + start = 3 data = bytearray((0, 1)) * (n // 2) - data[:3] = 0, 0, 0 limit = math.isqrt(n) + 1 - for p in compress(range(limit), data): + for p in iter_index(data, 1, start, limit): + yield from iter_index(data, 1, start, p*p) data[p*p : n : p+p] = bytes(len(range(p*p, n, p+p))) - data[2] = 1 - return iter_index(data, 1) if n > 2 else iter([]) + start = p*p + yield from iter_index(data, 1, start) def factor(n): "Prime factors of n." |