On 20/03/06, Steve Nelson <[EMAIL PROTECTED]> wrote: > Hi All, > > I had a feeling I could do this: > > >>> foo > [[1, 2, 3], [1, 2, 3], [1, 2, 3]] > >>> for c in foo: > ... for b in c: > ... print b
What you're doing is called "flattening" a list. You can do it with a list comprehension: >>> foo = [[1,2,3], [4,5,6], [7,8,9]] >>> [x for y in foo for x in y] [1, 2, 3, 4, 5, 6, 7, 8, 9] There are also other ways; ActiveState has several in its cookbook. If you want to sum, you could also use a generator expression (requires Python 2.4): >>> sum(x for y in foo for x in y) 45 This will be slightly faster, depending on how big your list is. But really, there are times when clarity and efficiency both come together and say "Write explicit for loops" :-) -- John. _______________________________________________ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
