如何在一个月内滚动开始和结束日期?

Question

我想写一个展望 1 年的函数，但可以接受某个月份作为开始计数的日期。

例如，如果开始时间为1/1/2011，则结束时间为1/1/2012。新的开始时间将是1/2/2011新的结束时间将是1/2/2012。开始和结束时间应该这样推进。

这是我的尝试：

import datetime
from dateutil.relativedelta import relativedelta
from datetime import date
def Count(StartDate, EndDate,count):
#while StartDate < FinalDate:
count = 1
print (StartDate, EndDate)
StartDate = date(2011,01,01)
FinalDate = date (2014,01,01)
EndDate = StartDate + relativedelta(years=+1)
count = 1

a = Count(StartDate, EndDate,count)
print a

打印类似的东西

(datetime.date(2011, 2, 1), datetime.date(2012, 2, 1))
None
(datetime.date(2011, 3, 1), datetime.date(2012, 3, 1))
None
(datetime.date(2011, 4, 1), datetime.date(2012, 4, 1))
None
(datetime.date(2011, 5, 1), datetime.date(2012, 5, 1))
None
(datetime.date(2011, 6, 1), datetime.date(2012, 6, 1))
None

Answer 1

from dateutil.relativedelta import relativedelta
new_date = old_date + relativedelta(years=1)
#you can use this for getting the 1 year later date 
#or use
#adding to date
from datetime import datetime, timedelta
new_date = datetime.today()
new_date = new_date + timedelta(months=1)
new_date = new_date + timedelta(years=1)

Answer 2

import datetime
from dateutil.relativedelta import relativedelta
from datetime import date
def Count(StartDate, EndDate,count):
#while StartDate < FinalDate:
count = 1
print (StartDate, EndDate)
StartDate = date(2011,01,01)
FinalDate = date (2014,01,01)
EndDate = StartDate + relativedelta(years=+1)
count = 1
while StartDate < FinalDate:
StartDate = StartDate + relativedelta(months=+1)
EndDate = StartDate + relativedelta(years=+1)
a = Count(StartDate, EndDate,count)
print a