Fix stability of heapq's nlargest() and nsmallest().
diff --git a/Lib/heapq.py b/Lib/heapq.py
index 04725cd..753c3b7 100644
--- a/Lib/heapq.py
+++ b/Lib/heapq.py
@@ -130,7 +130,7 @@
'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 @@
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 @@
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