grouper

grouper.py

from itertools import zip_longest, islice

def grouper(iterable, n):
    return zip(*[iter(iterable)] * n)

def grouper_longest(iterable, n, fillvalue=None):
    return zip_longest(*[iter(iterable)] * n, fillvalue=fillvalue)

i0 = []
i1 = [1]
i2 = [1,2,3,4]
i3 = [1,2,3,4,5]
i4 = [1,2,3,4,5,6,7,8]
i5 = [1,2,3,4,5,6,7,8,9]
i6 = [1,2,3,4,5,6,7,8,9,10,11,12]

for g in islice(grouper(i0, 4), 2):
    print(g)

for g in islice(grouper(i1, 4), 2):
    print(g)

for g in islice(grouper(i2, 4), 2):
    print(g)

for g in islice(grouper(i3, 4), 2):
    print(g)

for g in islice(grouper(i4, 4), 2):
    print(g)

for g in islice(grouper(i5, 4), 2):
    print(g)

for g in islice(grouper(i6, 4), 2):
    print(g)


for g in islice(grouper_longest(i0, 4), 2):
    print(g)

for g in islice(grouper_longest(i1, 4), 2):
    print(g)

for g in islice(grouper_longest(i2, 4), 2):
    print(g)

for g in islice(grouper_longest(i3, 4), 2):
    print(g)

for g in islice(grouper_longest(i4, 4), 2):
    print(g)

for g in islice(grouper_longest(i5, 4), 2):
    print(g)

for g in islice(grouper_longest(i6, 4), 2):
    print(g)


def group_walk(iterable, group_size):
    """Yields len(iterable) - group_size + 1 groups of group_size from iterable

    EXAMPLE:
    >>> iterable = [1,2,3,4]
    >>> for group in group_walk(iterable, 2):
    ...     print(group)
    ...
    [1, 2]
    [2, 3]
    [3, 4]
    >>>

    NOTES:
    group_walk() will yield NOTHING if:
    len(iterable) < 2; or
    group_size < 2; just use standard iteration if you want "groups" of one!

    TODO:
    if 2 > group_size | len(iterable):
        raise ValueError
    """
    for i in range(len(iterable[:1 - group_size])):
        yield iterable[i:i + group_size]
 
 
#none
l = []
group_walk(l)
#1
l = [(2012, 3)]
group_walk(l)
#2
l = [(2012, 3), (2012, 4)]
group_walk(l)
#3
l = [(2012, 3), (2012, 4), (2013, 1)]
group_walk(l)
#4
l = [(2012, 3),(2012, 4),(2013, 1),(2013, 2)]
group_walk(l)
#5
l = [(2012, 3), (2012, 4), (2013, 1), (2013, 2), (2013, 3)]
group_walk(l)
#10
l = [(2012, 3), (2012, 4), (2013, 1), (2013, 2), (2013, 3), (2013, 4), (2014, 1), (2014, 2), (2014, 3), (2014, 4)]
group_walk(l)