pyhton 获得前几个月

#! /usr/bin/python
# -*- coding: utf-8 -*-

import sys
import time
import datetime
import sys
reload(sys)
sys.setdefaultencoding("utf-8")

def getLastMonth(day = None, months=1):
    if day:
        today = day
    else:
        today = datetime.date.today()
    
    y = int(months/12)
    m = months%12

    if today.month - m <= 0:
        y = y + 1
        m = 12 + (today.month-m)
        nextMonth = today.replace(year=today.year-y, month=m, day=1)
    elif m == 0:
        nextMonth = today.replace(year=today.year-y, day=1)
    else:
        nextMonth = today.replace(year=today.year-y, month=today.month-m, day=1)
    return nextMonth



d = datetime.date.today()
d=getLastMonth()
print d.strftime("%Y-%m-01")
d = datetime.date.today()
for i in (1,2,3,4,5,6,7,8,9,10,11,12,13,14,15):
    d=getLastMonth(day = d, months=11)
    print d.strftime("%Y-%m-01")

print "............................."
d = datetime.date(2011, 1, 1)
for i in (1,2,3,4,5,6,7,8,9,10,11,12,13,14,15):
    d=getLastMonth(day = d, months=11)
    print d.strftime("%Y-%m-01")