Pairwise circular Python 'for' loop

Question

Is there a nice Pythonic way to loop over a list, retuning a pair of elements? The last element should be paired with the first.

So for instance, if I have the list

Answer 1

I like a solution that does not modify the original list and does not copy the list to temporary storage:

def circular(a_list):
    for index in range(len(a_list) - 1):
        yield a_list[index], a_list[index + 1]
    yield a_list[-1], a_list[0]

for x in circular([1, 2, 3]):
    print x

Output:

(1, 2)
(2, 3)
(3, 1)

I can imagine this being used on some very large in-memory data.