python time, datetime, string, timestamp相互转换

原文链接

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# Python Time Conversion #

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-- 一. 时间的表示类型 --

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py中可能涉及的time有四种类型

    1. time string

    2. datetime tuple(datetime obj)

    3. time tuple(time obj)

    4. timestamp

1. time string

string是最简单的表示time的方式

如如下代码生成的即为string

    ----------------------------------------------

    >>> time.ctime()

    'Mon Dec 17 21:02:55 2012'

    ----------------------------------------------

或者更简单的生成一个字符串

    ----------------------------------------------

    time_string = '2000-01-02 03:04:05'

    ----------------------------------------------

2. datetime tuple(datetime obj)

datetime tuple是datetime.datetime对象类型

    ----------------------------------------------

    >>> datetime.now()

    datetime.datetime(2012, 12, 17, 21, 3, 44, 139715)

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3. time tuple(time obj)

time tuple是time.struct_time对象类型

    ----------------------------------------------

    time.struct_time(tm_year=2008, tm_mon=11, tm_mday=10, tm_hour=17, tm_min=53, tm_sec=59, tm_wday=0, tm_yday=315, tm_isdst=-1)

    ----------------------------------------------

4. timestamp

时间戳类型:自1970年1月1日(00:00:00 GMT)以来的秒数

    ----------------------------------------------

    >>> time.time()

    1355749338.05917

    ----------------------------------------------

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-- 二. 类型之间的转换 --

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1. string 转换为其它

初始化:

    date_str = "2008-11-10 17:53:59"

1.1 string --> datetime obj

导入:

    import datetime

    datetime.datetime.strptime(string, format)

eg

    ----------------------------------------------

    >>> dt_obj = datetime.datetime.strptime(date_str, "%Y-%m-%d %H:%M:%S")

    >>> dt_obj

    datetime.datetime(2008, 11, 10, 17, 53, 59)

    ----------------------------------------------

1.2 string --> time obj

导入:

    import time

    time.strptime(string, format)

eg

    ----------------------------------------------

    #time模块有类似datetime中的strptime()函数

    >>> date_str = "2008-11-10 17:53:59"

    >>> t_obj = time.strptime(date_str, "%Y-%m-%d %H:%M:%S")

    >>> t_obj

    time.struct_time(tm_year=2008, tm_mon=11, tm_mday=10, tm_hour=17, tm_min=53, tm_sec=59, tm_wday=0, tm_yday=315, tm_isdst=-1)

    ----------------------------------------------

2. datetime obj转换为其它

datetime obj转换为其它类型,用的都是datetime的函数

初始化:

    dt_obj = datetime.datetime(2008, 11, 10, 17, 53, 59)

2.1 dt obj --> string

    ----------------------------------------------

    date_str = dt_obj.strftime("%Y-%m-%d %H:%M:%S")

    ----------------------------------------------

2.2 dt obj --> time obj

    ----------------------------------------------

    time_tuple = dt_obj.timetuple()

    ----------------------------------------------

3. time obj转换为其它

初始化:

    time_tuple = (2008, 11, 12, 13, 51, 18, 2, 317, 0)

3.1 time obj --> string

    ----------------------------------------------

    date_str = time.strftime("%Y-%m-%d %H:%M:%S", time_tuple)

    ----------------------------------------------

3.2 time obj --> datetime obj

    ----------------------------------------------

    datetime.datetime(*time_tuple[0:6])

    ----------------------------------------------

3.3 time obj --> timestamp

    ----------------------------------------------

    ts = time.mktime(time_tuple)

    ----------------------------------------------

4. timestamp转换为其它

初始化:

    timestamp = 1226527167.595983

--!!--注意以下两种都使用local时区

4.1 timestamp --> dt obj

    ----------------------------------------------

    dt_obj = datetime.fromtimestamp(timestamp)

    ----------------------------------------------

4.2 timestamp --> time obj

    ----------------------------------------------

    time_tuple = time.localtime(timestamp)

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--!!--以下两种方式和时区相关,比较标准时区时间和本地时区时间

4.3 使用UTC --> dt obj

    ----------------------------------------------

    #本地时区时间

    >>> datetime.datetime.fromtimestamp(tm)

    datetime.datetime(2012, 12, 17, 23, 39, 58, 401881)

    #标准时区时间

    >>> datetime.datetime.utcfromtimestamp(tm)

    datetime.datetime(2012, 12, 17, 15, 39, 58, 401881)

    ----------------------------------------------

4.4 使用UTC --> time obj

    ----------------------------------------------

    #本地时区时间

    >>> time.localtime(tm)

    time.struct_time(tm_year=2012, tm_mon=12, tm_mday=17, tm_hour=23, tm_min=39, tm_sec=58, tm_wday=0, tm_yday=352, tm_isdst=0)

    #标准时区时间

    >>> time.gmtime(tm)

    time.struct_time(tm_year=2012, tm_mon=12, tm_mday=17, tm_hour=15, tm_min=39, tm_sec=58, tm_wday=0, tm_yday=352, tm_isdst=0)

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