On Fri, Oct 30, 2009 at 5:31 AM, Shashwat Anand <anand.shash...@gmail.com>wrote:
> *# 1:* > > >>> sum([1, 2, 3], 4) > 10 > > How does it actually work ? > ( ( (1 + 2) + 3) + 4) or ( ( (4 + 1) + 2 + 3) > ( ( (4 + 1) + 2 + 3) 4 is the 'start' > >>> sum ( [ [ 1 ], [ 2, 3 ] ], [ ]) > [1, 2, 3] > What's happening here exactly ? > (([] + [1]) + [2, 3]) > [ 1] + [2, 3] = [1, 2, 3] is understandable, but why do we pass a [ ] as a > [start] parameter to do so ? > The start defaults to 0. So you'll get ((0 + [1]) + [2, 3]) which is a type error. Cannot add 0 to a list. > >>> reduce(operator.mul, [1, 2, 3], 4) > 24 > how does it works ? > ( ( (1 * 2) * 3) * 4) or (((4 * 1) * 2) * 3) > (((4 * 1) * 2) * 3) >>>reduce( operator.mul, lst) > > Can it be done via List Comprehension or we have to do dirty hacks as > mentioned above :( > Can the LCM function be reduced ? > Something like this should work: def lcm2(a, b): return a*b/fractions.gcd(a,b) def lcm(mylist): return reduce(lcm2, mylist) _______________________________________________ BangPypers mailing list BangPypers@python.org http://mail.python.org/mailman/listinfo/bangpypers
