On Aug 22, 7:12 pm, Tim Chase <python.l...@tim.thechases.com> wrote: > On 08/22/10 12:50, Baba wrote: > > > > > level: beginners > > > I was trying to write simple code that compares 2 tuples and returns > > any element in the second tuple that is not in the first tuple. > > > def tuples(t1, t2): > > result = [] > > for b in t2: > > for a in t1: > > if b == a: > > break > > else: > > result=result+[b,] > > return result > > > print tuples([0,5,6], [0,5,6,3,7]) > > > the code works but i was surprised by the following: my understanding > > was that an ELSE clause is part of an IF statement. Therefore it comes > > at the same indentation as the IF statement. > > The ELSE clause can be used either with an IF (as you know) or > with a FOR loop, which is interpreted as "if this loop reached > the end naturally instead of exiting via a BREAK statement, > execute this block of code". > > If you reach the end of t1 without having found a value (and then > issuing a "break"), then the current value of t2 (b) should be > appended to the result. > > That said, unless order matters, I'd just use sets: > > def tuples(t1, t2): > return list(set(t2)-set(t1)) > > which should have better performance characteristics for large > inputs. > > -tkc
Thanks Tim! -- http://mail.python.org/mailman/listinfo/python-list
