Rolling or sliding window iterator?

Question

I need a rolling window (aka sliding window) iterable over a sequence/iterator/generator. Default Python iteration can be considered a special case, where the window length

Answer 1

I like tee():

from itertools import tee, izip

def window(iterable, size):
    iters = tee(iterable, size)
    for i in xrange(1, size):
        for each in iters[i:]:
            next(each, None)
    return izip(*iters)

for each in window(xrange(6), 3):
    print list(each)

gives:

[0, 1, 2]
[1, 2, 3]
[2, 3, 4]
[3, 4, 5]