On Jun 23, 9:16 pm, Maric Michaud <[EMAIL PROTECTED]> wrote: > Le Monday 23 June 2008 11:39:44 Boris Borcic, vous avez écrit : > > > John Machin wrote: > > > Instead of sum(a + b for a, b in zip(foo, bar)) > > > why not use sum(foo) + sum(bar) > > > ? > > > or even sum(foo+bar) as may apply. > > Because some are better than others : > > sum(foo+bar) is the worst, it create a superfluous list of len(foo) + len(bar) > elements. > > sum(a + b for a, b in zip(foo, bar)), creates a list of max(len(foo), > len(bar)) elements, in most cases it is the same as the former. > > This could have been corrected using itertools.izip. > > So the winner is sum(foo) + sum(bar), which does not create anything not > needed. > > But if the question is "how to build the list and sum up all elements in a > efficient way for sequences of arbitrary length ", it's important to make it > in the same iteration, so the most effective/clear, and so "pythonic", way to > do this is (untested) : > > res, sum = [], 0
Please use tot or total, not sum! > for s in (a + b for a, b > in zip(itertools.izip(xrange(1, 51), Perhaps you should not have left zip() in there ... > xrange(50, 0, -1)))): > sum += s > res.append(sum) Do you mean res.append(s) ? I would have thought that it would have been better to create the list and then sum it: res = [a + b for a, b in itertools.izip(foo_iter, bar_iter)] total = sum(res) Cheers, John -- http://mail.python.org/mailman/listinfo/python-list
