[Python-checkins] Improve speed. Reduce auxiliary memory to 16.6% of the main array. (GH-98294)
rhettinger
webhook-mailer at python.org
Sat Oct 15 17:05:37 EDT 2022
https://github.com/python/cpython/commit/3a639bbeace73d54f7e5431d3224c8c8223d81ae
commit: 3a639bbeace73d54f7e5431d3224c8c8223d81ae
branch: main
author: Raymond Hettinger <rhettinger at users.noreply.github.com>
committer: rhettinger <rhettinger at users.noreply.github.com>
date: 2022-10-15T16:05:28-05:00
summary:
Improve speed. Reduce auxiliary memory to 16.6% of the main array. (GH-98294)
files:
M Doc/library/itertools.rst
diff --git a/Doc/library/itertools.rst b/Doc/library/itertools.rst
index 056b0788a4d8..88e1e5aa6ef7 100644
--- a/Doc/library/itertools.rst
+++ b/Doc/library/itertools.rst
@@ -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] = bytes(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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