Author: raymond.hettinger Date: Wed Dec 31 05:18:44 2008 New Revision: 68095 Log: Issue 4790: Eliminate unnecessary work from heapq's nlargest() and nsmallest() functions for the common case where no key function is specified. Modified: python/branches/release26-maint/Lib/heapq.py python/branches/release26-maint/Misc/NEWS Modified: python/branches/release26-maint/Lib/heapq.py ============================================================================== --- python/branches/release26-maint/Lib/heapq.py (original) +++ python/branches/release26-maint/Lib/heapq.py Wed Dec 31 05:18:44 2008 @@ -354,6 +354,10 @@ Equivalent to: sorted(iterable, key=key)[:n] """ + if key is None: + it = izip(iterable, count()) # decorate + result = _nsmallest(n, it) + return map(itemgetter(0), result) # undecorate in1, in2 = tee(iterable) it = izip(imap(key, in1), count(), in2) # decorate result = _nsmallest(n, it) @@ -365,6 +369,10 @@ Equivalent to: sorted(iterable, key=key, reverse=True)[:n] """ + if key is None: + it = izip(iterable, imap(neg, count())) # decorate + result = _nlargest(n, it) + return map(itemgetter(0), result) # undecorate in1, in2 = tee(iterable) it = izip(imap(key, in1), imap(neg, count()), in2) # decorate result = _nlargest(n, it) Modified: python/branches/release26-maint/Misc/NEWS ============================================================================== --- python/branches/release26-maint/Misc/NEWS (original) +++ python/branches/release26-maint/Misc/NEWS Wed Dec 31 05:18:44 2008 @@ -44,6 +44,9 @@ Library ------- +- Issue 4790: The nsmallest() and nlargest() functions in the heapq module + did unnecessary work in the common case where no key function was specified. + - Issue #3767: Convert Tk object to string in tkColorChooser. - Issue #3248: Allow placing ScrolledText in a PanedWindow.