for http://stackoverflow.com/questions/23075453/

from itertools import groupby
from pprint import pprint

months = ['1/2013', '7/2013', '2/2013', '3/2013', '4/2014', '12/2013', '10/2013', '11/2013',
          '1/2014', '2/2014']

def year_month(date):
    m, y = date.split('/')
    return int(y)*12 + int(m)

L = [[date for _, date in run]
     for _, run in groupby(enumerate(sorted(months, key=year_month)),
                           key=lambda (i, date): (i - year_month(date)))]
pprint(L)