关于python日期计算的一个扩展库relativedelta

 

主要是使用relativedelta类。初始化参数months是月的差异。 
安装这个库也很简单，执行命令pip install python-dateutil。

import datetime
from dateutil.relativedelta import relativedelta

if __name__ == "__main__":
    print(datetime.date.today() - relativedelta(months=+1))

　　

代码在 
https://github.com/dateutil/dateutil/blob/master/dateutil/relativedelta.py

if self.months:
            assert 1 <= abs(self.months) <= 12
            month += self.months
            if month > 12:
                year += 1
                month -= 12
            elif month < 1:
                year -= 1
                month += 12
        day = min(calendar.monthrange(year, month)[1],
                  self.day or other.day)

　　

参考： 
https://dateutil.readthedocs.io/en/stable/ 
https://github.com/dateutil/dateutil