Iterate through pairs of items in a Python list

From the itertools recipes:

from itertools import tee

def pairwise(iterable):
    "s -> (s0,s1), (s1,s2), (s2, s3), ..."
    a, b = tee(iterable)
    next(b, None)
    return zip(a, b)

for v, w in pairwise(a):
    ...

You can zip the list with itself sans the first element:

a = [5, 7, 11, 4, 5]

for previous, current in zip(a, a[1:]):
    print(previous, current)

This works even if your list has no elements or only 1 element (in which case zip returns an empty iterable and the code in the for loop never executes). It doesn't work on generators, only sequences (tuple, list, str, etc).

To do that you should do:

a =  [5, 7, 11, 4, 5]
for i in range(len(a)-1):
    print [a[i], a[i+1]]