In article <mailman.16552.1417688329.18130.python-l...@python.org>, Chris Angelico <ros...@gmail.com> wrote: >On Thu, Dec 4, 2014 at 9:09 PM, Albert van der Horst ><alb...@spenarnc.xs4all.nl> wrote: >>>If there is more than one item with the maximum calculated the first is >>>given, so for your attempt >>> >>>max(xrange(100,200), key=lambda i: i%17==0 ) >> >>> >>>the values False, False, True, False, ... are calculated and because >>> >>>>>> True > False >>>True >>> >>>the first one with a True result is returned. >>> >> >> So in that case max doesn't return the maximum (True), but instead >> something else. >> >> Useful as that function may be, it shouldn't have been called max. >> >> I don't blame myself for being misled. > >If lots of them are equally the largest, by whatever definition of >largest you have, it has to do one of three things: > >1) Raise an exception >2) Return multiple items (either as a tuple, or a generator, or something) >3) Pick one of them and return it. > >Python's max() does the third, and for the picking part, uses the >first one it comes across - a decent way to do it. > >If there's no clear maximum, it can't do any better than that. It's >still returning something for which there is no greater.
I agree that it is a useful function and that it is doing the right thing. What is wrong is the name. I refer to the fact that it is not returning the maximum. It returns the iterator value that leads to the maximum. A function that doesn't return a maximum shouldn't be called maximum. > >ChrisA -- Albert van der Horst, UTRECHT,THE NETHERLANDS Economic growth -- being exponential -- ultimately falters. albert@spe&ar&c.xs4all.nl &=n http://home.hccnet.nl/a.w.m.van.der.horst -- https://mail.python.org/mailman/listinfo/python-list
