Iterate over pairs in a list (circular fashion) in Python

Question

The problem is easy, I want to iterate over each element of the list and the next one in pairs (wrapping the last one with the first).

I\'ve thought about two unpyth

Answer 1

I'd do it like this (mostly because I can read this):

class Pairs(object):
    def __init__(self, start):
        self.i = start
    def next(self):
        p, p1 = self.i, self.i + 1
        self.i = p1
        return p, p1
    def __iter__(self):
        return self

if __name__ == "__main__":
    x = Pairs(0)
    y = 1
    while y < 20:
        print x.next()
        y += 1

gives:

(0, 1)
(1, 2)
(2, 3)
(3, 4)
(4, 5)
(5, 6)
(6, 7)
(7, 8)
(8, 9)