python 之日期时间处理

##python时间操作一般使用time、datetime两个模块

对于time模块，时间的表示模式有３种
1、时间戳：time.time()
2、字符串: time.strftime('%Y%m%d')
3、struct_time格式: time.localtime()

如下所示：

 #时间操作
 >>> import time
 >>> time.time()
 1450336566.81052
 >>> time.localtime()
 time.struct_time(tm_year=2015, tm_mon=12, tm_mday=17, tm_hour=15, tm_min=16, tm_sec=14, tm_wday=3, tm_yday=351, tm_isdst=0)
 >>> time.strftime('%Y%m%d %H%M%S')
 '20151217 151632'
 >>> time.strptime('20151212 121212','%Y%m%d %H%M%S')
 time.struct_time(tm_year=2015, tm_mon=12, tm_mday=12, tm_hour=12, tm_min=12, tm_sec=12, tm_wday=5, tm_yday=346, tm_isdst=-1)
 >>> time.mktime(time.localtime())
 1450336685.0
 >>>
 >>> yesterday = time.strftime('%Y-%m-%d 00:00:00',time.localtime(time.time()-3600*24))
 >>> print yesterday
 2015-12-16 00:00:00
 >>> tomorrow = time.strftime('%Y-%m-%d 00:00:00',time.localtime(time.time()+3600*24))
 >>> print tomorrow
 2015-12-18 00:00:00

datetime对于时间计算很有用
datetime模块下有几个比较有用的方法　datetime,date,time,timedelta
语法: datetime(year, month, day[, hour[, minute[, second[, microsecond[,tzinfo]]]]])
date(year, month, day) --> date object
time([hour[, minute[, second[, microsecond[, tzinfo]]]]]) --> a time object
timedelta(days=1,hours=2,minutes=3,seconds=4)
calendar.monthrange(year, month)：判断由year和month组成月份，返回该月第一天为周几和该月总共有多少天

 ##取日期列表
 from datetime import datetime,date,timedelta
 def get_range_time(begin,end,step):
     while begin < end:
         yield begin
         begin = begin + step

 for i in get_range_time(datetime(2015,11,2),datetime(2016,3,2),timedelta(days=1)):
     print i

 from datetime import datetime,date,timedelta
 import calendar

 #取动态月（自然月需要置day=1）,如下
 def get_month_range(startdate = None):
     if startdate is None:
         startdate = date.today().replace(day=1)
     _,days_in_month = calendar.monthrange(startdate.year,startdate.month)
     enddate = startdate + timedelta(days=days_in_month)
     return startdate,enddate

 begin,end = get_month_range()
 add_step = timedelta(days=1)
 while begin < end:
     print begin
     begin = begin + add_step

请记住以下时间转换关系图