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Improve speed. Reduce auxiliary memory to 16.6% of the main array. #98294

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Merged
merged 3 commits into from
Oct 15, 2022
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Improve speed. Reduce auxiliary memory to 16.6% of the main array. #98294

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36ea21d
Improve speed. Reduce auxiliary memory load to 16.6% of the main array.
rhettinger Oct 15, 2022
de5fc2f
Merge branch 'main' into sieve_faster_smaller
rhettinger Oct 15, 2022
ec05c8a
Zeros array is immutable
rhettinger Oct 15, 2022
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Improve speed. Reduce auxiliary memory load to 16.6% of the main array.
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@rhettinger
rhettinger committed Oct 15, 2022
commit 36ea21d6a424ba325cdb9d8608989e58463f9090
9 changes: 5 additions & 4 deletions Doc/library/itertools.rst
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Expand Up @@ -822,12 +822,13 @@ which incur interpreter overhead.
def sieve(n):
"Primes less than n"
# sieve(30) --> 2 3 5 7 11 13 17 19 23 29
data = bytearray([1]) * n
data[:2] = 0, 0
data = bytearray((0, 1)) * (n // 2)
data[:3] = 0, 0, 0
limit = math.isqrt(n) + 1
for p in compress(range(limit), data):
data[p*p : n : p] = bytearray(len(range(p*p, n, p)))
return iter_index(data, 1)
data[p*p : n : p+p] = bytearray(len(range(p*p, n, p+p)))
data[2] = 1
return iter_index(data, 1) if n > 2 else iter([])

def flatten(list_of_lists):
"Flatten one level of nesting"
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