PYTHON-基础-时间日期处理小结

1. Python 获取昨天日期

以下代码通过导入 datetime 模块来获取昨天的日期：

# 引入 datetime 模块
import datetime
def getYesterday():
    today=datetime.date.today()
    oneday=datetime.timedelta(days=1)
    yesterday=today-oneday
    return yesterday

# 输出
print(getYesterday())

执行以上代码输出结果为：

2015-06-10

以上实例输出的意思为昨天的日期是 2015 年 6 月 10 日。

2. 涉及对象

datetime

>>> import datetime
>>> now = datetime.datetime.now()
>>> now
datetime.datetime(2015, 1, 12, 23, 9, 12, 946118)
>>> type(now)
<type 'datetime.datetime'>

now()函数返回的对象是datetime.datetime类型的。

timestamp

>>> import time
>>> time.time()
1421075455.568243

time tuple

>>> import time
>>> time.localtime()
time.struct_time(tm_year=2015, tm_mon=1, tm_mday=12, tm_hour=23, tm_min=10, tm_sec=30, tm_wday=0, tm_yday=12, tm_isdst=0)

string

>>> import datetime
>>> datetime.datetime.now().strftime("%Y-%m-%d %H:%M:%S")
'2015-01-12 23:13:08'

注意：strftime和strptime函数返回的数据的类型是string，不是datetime.datetime类型的。

date

>>> import datetime
>>> datetime.datetime.now().date()
datetime.date(2015, 1, 12)

3. datetime基本操作

获取当前datetime

>>> import datetime
>>> datetime.datetime.now()
datetime.datetime(2015, 1, 12, 23, 26, 24, 475680)

获取当天date

>>> datetime.date.today()
datetime.date(2015, 1, 12)

获取明天/前N天

明天

>>> datetime.date.today() + datetime.timedelta(days=1)
datetime.date(2015, 1, 13)

三天前

>>> datetime.datetime.now()
datetime.datetime(2015, 1, 12, 23, 38, 55, 492226)
>>> datetime.datetime.now() - datetime.timedelta(days=3)
datetime.datetime(2015, 1, 9, 23, 38, 57, 59363)

获取当天开始和结束时间(00:00:00 23:59:59)

>>> datetime.datetime.combine(datetime.date.today(), datetime.time.min)
datetime.datetime(2015, 1, 12, 0, 0)
>>> datetime.datetime.combine(datetime.date.today(), datetime.time.max)
datetime.datetime(2015, 1, 12, 23, 59, 59, 999999)

获取两个datetime的时间差

>>> (datetime.datetime(2015,1,13,12,0,0) - datetime.datetime.now()).total_seconds()
44747.768075

得到的时间是前面的时间减去后面的时间的秒数

获取本周/本月/上月最后一天

本周的最后一天

>>> today = datetime.date.today()
>>> today
datetime.date(2015, 1, 12)
>>> sunday = today + datetime.timedelta(6 - today.weekday())
>>> sunday
datetime.date(2015, 1, 18)

today.weekday()返回的是本周已经过去了几天（不包含今天）。
这种计算方法可以理解为：每周七天，一共有六跳。
today.weekday的返回值可以理解为已经发生了多少跳。

本月的最后一天

>>> import calendar
>>> today = datetime.date.today()
>>> _, last_day_num = calendar.monthrange(today.year, today.month)
>>> last_day = datetime.date(today.year, today.month, last_day_num)
>>> last_day
datetime.date(2015, 1, 31)

获取上个月的最后一天(可能跨年)

>>> import datetime
>>> today = datetime.date.today()
>>> first = datetime.date(day=1, month=today.month, year=today.year)
>>> last_month = first - datetime.timedelta(days=1)

几个对象之间的关系转换：

Datetime Object / String / timestamp / time tuple

datetime <=> string

>>> import datetime
>>> datetime.datetime.now().strftime("%Y-%m-%d %H:%M:%S")
'2015-01-12 23:13:08'

>>> import datetime
>>> datetime.datetime.strptime("2014-12-31 18:20:10", "%Y-%m-%d %H:%M:%S")
datetime.datetime(2014, 12, 31, 18, 20, 10)

datetime <=> timetuple

>>> import datetime
>>> datetime.datetime.now().timetuple()
time.struct_time(tm_year=2015, tm_mon=1, tm_mday=12, tm_hour=23, tm_min=17, tm_sec=59, tm_wday=0, tm_yday=12, tm_isdst=-1)

timetuple => timestamp => datetime [看后面datetime<=>timestamp]

datetime <=> date

>>> import datetime
>>> datetime.datetime.now().date()
datetime.date(2015, 1, 12)

http://www.wklken.me/posts/2015/03/03/python-base-datetime.html#1-datetime