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From: Ian Kelly <ian.g.kelly@gmail.com>
Date: Sun, 21 Oct 2012 12:51:51 -0600
Subject: Re: get each pair from a string.
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On Sun, Oct 21, 2012 at 12:33 PM, Vincent Davis
<vincent@vincentdavis.net> wrote:
> I am looking for a good way to get every pair from a string. For example,
> input:
> x = 'apple'
> output
> 'ap'
> 'pp'
> 'pl'
> 'le'
>
> I am not seeing a obvious way to do this without multiple for loops, but
> maybe there is not :-)

Use the "pairwaise" recipe from the itertools docs:

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

> In the end I am going to what to get triples, quads....... also.

Generalizing:

def nwise(iterable, n=2):
    iters = tee(iterable, n)
    for i, it in enumerate(iters):
        for _ in range(i):
            next(it, None)
    return izip(*iters)