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In Py3.x, a list comprehension is now faster than list(map(itemgetter(0), iterable)).

This commit is contained in:
Raymond Hettinger 2009-02-21 23:20:57 +00:00
parent 912fbcade3
commit ba86fa9d5f
1 changed files with 4 additions and 5 deletions
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9
Lib/heapq.py
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@ -130,7 +130,6 @@ __all__ = ['heappush', 'heappop', 'heapify', 'heapreplace', 'merge',
'nlargest', 'nsmallest', 'heappushpop']
from itertools import islice, repeat, count, tee, chain
from operator import itemgetter
import bisect
def heappush(heap, item):
@ -377,13 +376,13 @@ def nsmallest(n, iterable, key=None):
if key is None:
it = zip(iterable, count()) # decorate
result = _nsmallest(n, it)
return list(map(itemgetter(0), result)) # undecorate
return [r[0] for r in result] # undecorate
# General case, slowest method
in1, in2 = tee(iterable)
it = zip(map(key, in1), count(), in2) # decorate
result = _nsmallest(n, it)
return list(map(itemgetter(2), result)) # undecorate
return [r[2] for r in result] # undecorate
_nlargest = nlargest
def nlargest(n, iterable, key=None):
@ -415,13 +414,13 @@ def nlargest(n, iterable, key=None):
if key is None:
it = zip(iterable, count(0,-1)) # decorate
result = _nlargest(n, it)
return list(map(itemgetter(0), result)) # undecorate
return [r[0] for r in result] # undecorate
# General case, slowest method
in1, in2 = tee(iterable)
it = zip(map(key, in1), count(0,-1), in2) # decorate
result = _nlargest(n, it)
return list(map(itemgetter(2), result)) # undecorate
return [r[2] for r in result] # undecorate
if __name__ == "__main__":
# Simple sanity test