Split a number in batches

split_in_columns.py

'''
Split a long number in batches.

>>> k = 178684461669052552311410692812805706249615844217278044703496837914086683543763273909969771627106004287604844670397177991379601L

>>> print pretty(k)
17868446 16690525 52311410 69281280 57062496 15844217 27804470 34968379
14086683 54376327 39099697 71627106 00428760 48446703 97177991 379601

>>> print pretty(k, 3, 9)
178 684 461 669 052 552 311 410 692
812 805 706 249 615 844 217 278 044
703 496 837 914 086 683 543 763 273
909 969 771 627 106 004 287 604 844
670 397 177 991 379 601

>>> print pretty(k, 2, 6)
17 86 84 46 16 69
05 25 52 31 14 10
69 28 12 80 57 06
24 96 15 84 42 17
27 80 44 70 34 96
83 79 14 08 66 83
54 37 63 27 39 09
96 97 71 62 71 06
00 42 87 60 48 44
67 03 97 17 79 91
37 96 01
'''

import itertools

def split_columns(iterable, size):
    c = itertools.count()
    for k, g in itertools.groupby(iterable, lambda item: c.next() // size):
        yield list(g)

def pretty(number, size=8, per_line=8):
    groups = split_columns(split_columns(str(number), size), per_line)
    lines = (' '.join(''.join(group) for group in line) for line in groups)
    return '\n'.join(lines)