How to group elements in python by n elements

You can use the grouper function from the recipes in the itertools documentation:

from itertools import zip_longest

def grouper(iterable, n, fillvalue=None):
    """Collect data into fixed-length chunks or blocks.

    >>> grouper('ABCDEFG', 3, 'x')
    ['ABC', 'DEF', 'Gxx']
    """
    args = [iter(iterable)] * n
    return zip_longest(*args, fillvalue=fillvalue)