On 12 Aug 2014, at 10:02, Armin Rigo <ar...@tunes.org> wrote: > Hi all, > > The core of the matter is that if we repeatedly __add__ strings from a > long list, we get O(n**2) behavior. For one point of view, the > reason is that the additions proceed in left-to-right order. Indeed, > sum() could proceed in a more balanced tree-like order: from [x0, x1, > x2, x3, ...], reduce the list to [x0+x1, x2+x3, ...]; then repeat > until there is only one item in the final list. This order ensures > that sum(list_of_strings) is at worst O(n log n). It might be in > practice close enough from linear to not matter. It also improves a > lot the precision of sum(list_of_floats) (though not reaching the same > precision levels of math.fsum()).
I wonder why nobody has mentioned previous year’s discussion of the same issue yet: http://marc.info/?l=python-ideas&m=137359619831497&w=2 Maybe someone can write a PEP about this that can be pointed when the question is discussed again next summer ;-) Ronald _______________________________________________ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
