On Apr 13, 1:39 am, Arnaud Delobelle <arno...@googlemail.com> wrote: > Duncan Booth <duncan.bo...@invalid.invalid> writes: > > Duncan Booth <duncan.bo...@invalid.invalid> wrote: > > >> John Posner <jjpos...@snet.net> wrote: > > >>> Do know what in the itertools implementation causes adding a 'if p <= > >>> sqrt(n)' clause to *decrease* performance, while adding a > >>> 'takewhile()' clause *increases* performance? > > >> I haven't timed it, but I would guess that the takewhile was faster > >> only because the sqrt(n) had been factored out of the loop. Try the > >> original loop again precalculating the sqrt(n) and see how that compares. > > > Which of course is rubbish, extracting the sdqrt will have an effect but > > the main factor is that takewhile exits the loop as soon as the condition > > is false whereas a conditional in a generator comprehension doesn't stop > > the loop continuing to the end. > > Absolutely! Since you hadn't quoted the original code, I'd forgotten > that it wasn't stopping after n**0.5. > > -- > Arnaud
-1 entertaining, list. Come on, people, the show must go on. Take five. -- http://mail.python.org/mailman/listinfo/python-list
