pure python ngrams

ngrams.py

from itertools import tee, zip_longest


def ngrams(iterable, n=3):
    """
    >>> list(ngrams(range(5), 3))
    [(0, 1, 2), (1, 2, 3), (2, 3, 4)]
    """
    ts = tee(iterable, n)
    for i, t in enumerate(ts[1:]):
        for _ in range(i+1):
            next(t, None)
    return zip(*ts)  # zip_longest