mirrors/cpython
1
0
Fork 0
mirror of https://github.com/python/cpython.git synced 2025-07-28 13:44:43 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 6

Fix stability of heapq's nlargest() and nsmallest().

Browse source
This commit is contained in:
Raymond Hettinger 2007-01-04 17:53:34 +00:00
parent 2dc4db0174
commit 769a40a1d0
2 changed files with 14 additions and 18 deletions
Download patch file Download diff file Expand all files Collapse all files

8
Lib/heapq.py
View file

@ -130,7 +130,7 @@ __all__ = ['heappush', 'heappop', 'heapify', 'heapreplace', 'nlargest',
'nsmallest']
from itertools import islice, repeat, count, imap, izip, tee
from operator import itemgetter
from operator import itemgetter, neg
import bisect
def heappush(heap, item):
@ -315,8 +315,6 @@ def nsmallest(n, iterable, key=None):
Equivalent to: sorted(iterable, key=key)[:n]
"""
if key is None:
return _nsmallest(n, iterable)
in1, in2 = tee(iterable)
it = izip(imap(key, in1), count(), in2) # decorate
result = _nsmallest(n, it)
@ -328,10 +326,8 @@ def nlargest(n, iterable, key=None):
Equivalent to: sorted(iterable, key=key, reverse=True)[:n]
"""
if key is None:
return _nlargest(n, iterable)
in1, in2 = tee(iterable)
it = izip(imap(key, in1), count(), in2) # decorate
it = izip(imap(key, in1), imap(neg, count()), in2) # decorate
result = _nlargest(n, it)
return map(itemgetter(2), result) # undecorate