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Issue #21424: Optimize heaqp.nlargest() to make fewer tuple comparisons.

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Consolidates the logic for nlargest() into a single function so that
decoration tuples (elem,order) or (key, order, elem) only need to
be formed when a new element is added to the heap.  Formerly, a tuple
was created for every element regardless of whether it was added to
the heap.

The change reduces the number of tuples created, the number of ordering
integers created, and total number of tuple comparisons.
This commit is contained in:
Raymond Hettinger 2014-05-11 01:55:46 -07:00
parent d6a46ae705
commit 277842eff1
4 changed files with 41 additions and 174 deletions
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2
Lib/test/test_heapq.py
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@ -13,7 +13,7 @@ c_heapq = support.import_fresh_module('heapq', fresh=['_heapq'])
# _heapq.nlargest/nsmallest are saved in heapq._nlargest/_smallest when
# _heapq is imported, so check them there
func_names = ['heapify', 'heappop', 'heappush', 'heappushpop',
'heapreplace', '_nlargest', '_nsmallest']
'heapreplace', '_nsmallest']
class TestModules(TestCase):
def test_py_functions(self):