Python's use of time-and datetime-related modules

First, preface

Learn about Python processing time-related modules, times, datetime

Second, Time module

First look at the time module

Take a look at help (time) to see what functions are available under the time module:

    time() -- return current time in seconds since the Epoch as a float    clock() -- return CPU time since process start as a float    sleep() -- delay for a number of seconds given as a float    gmtime() -- convert seconds since Epoch to UTC tuple    localtime() -- convert seconds since Epoch to local time tuple    asctime() -- convert time tuple to string    ctime() -- convert time in seconds to string    mktime() -- convert local time tuple to seconds since Epoch    strftime() -- convert time tuple to string according to format specification    strptime() -- parse string to time tuple according to format specification    tzset() -- change the local timezone

There are three ways to show time:

1. Timestamp (timestamp): The timestamp represents the offset that is calculated in seconds from 00:00:00 on January 1, 1970. The float type is returned, and the function that returns the timestamp has time (), clock ()

2, tuple (struct_time) mode: Struct_time tuple has 9 elements, the function that returns Struct_time mainly has Gmtime (), localtime (), Strptime (). Several elements in this way tuple are listed below:

3. Format the string (format time) way: Formatting times, formatted structures make time more readable. Includes custom formats and fixed formats. Like "2018-5-11."

Let's talk about some of the commonly used functions:

1, Time.sleep ()

Time.sleep (secs): Thread delays the specified time run. Unit is seconds.

2, Time.time ()

Gets the current time stamp

>>>time.time()      1525954582.579378

3, Time.clock ()

Calculate the time taken by the CPU calculation

>>>time.sleep(3)print(time.clock())0.061649

4, Time.gmtime ()

>>>a=time.gmtimeprint(a)time.struct_time(tm_year=2018, tm_mon=5, tm_mday=10, tm_hour=6, tm_min=53, tm_sec=30, tm_wday=3, tm_yday=130, tm_isdst=0)

The Gmtime () method is a struct_time that converts a timestamp to the UTC time zone (0 o'clock Zone). , a total of 9 parameters, meaning as shown in the chart above

5, Time.localtime ()

>>>a=time.localtime()print(a)time.struct_time(tm_year=2018, tm_mon=5, tm_mday=11, tm_hour=9, tm_min=22, tm_sec=14, tm_wday=4, tm_yday=131, tm_isdst=0)

Converts a timestamp to the struct_time of the current time zone. The secs parameter is not provided, whichever is the current time. , a total of 9 parameters, meaning as shown in the chart above

6, Time.asctime ([t]):

A tuple or struct_time representing time is represented in this form: ' Sun June 20 23:21:05 1993 '. If there are no parameters, Time.localtime () will be passed in as a parameter.

>>>time.asctime()‘Thu May 5 14:55:43 2011‘

Converts a timestamp to the struct_time of the current time zone. The secs parameter is not provided, whichever is the current time. , a total of 9 parameters, meaning as shown in the chart above

7, Time.ctime ()

>>>time.ctime(3600)print(a)Thu Jan  1 09:00:00 1970

Convert the timestamp to this form of ' Sun June 20 23:21:05 1993 ' Format time. If there are no parameters, Time.localtime () will be passed in as a parameter.

8, Time.strftime (format[, T])

>>>local_time = time.localtime()print(time.strftime(‘%Y-%m-%d  %H:%M:%S‘, local_time))2018-05-11  09:38:46

Converts a tuple or struct_time that represents time, such as returned by Time.localtime () and Time.gmtime (), to a formatted time string. If T is not specified, the Time.localtime () is passed in. If any of the elements in the tuple are out of bounds, the ValueError error will be thrown.

9, Time.strptime (string[, format])

>>>a=time.localtime()print(a)time.struct_time(tm_year=2018, tm_mon=5, tm_mday=11, tm_hour=9, tm_min=22, tm_sec=14, tm_wday=4, tm_yday=131, tm_isdst=0)

Converts a formatted time string to Struct_time. In fact it is inverse operation with strftime (). In this function, format defaults to: "%a%b%d%h:%m:%s%Y".

They convert relationships such as:

Time formatting:

%y 两位数的年份表示（00-99）%Y 四位数的年份表示（000-9999）%m 月份（01-12）%d 月内中的一天（0-31）%H 24小时制小时数（0-23）%I 12小时制小时数（01-12） %M 分钟数（00=59）%S 秒（00-59）%a 本地简化星期名称%A 本地完整星期名称%b 本地简化的月份名称%B 本地完整的月份名称%c 本地相应的日期表示和时间表示%j 年内的一天（001-366）%p 本地A.M.或P.M.的等价符%U 一年中的星期数（00-53）星期天为星期的开始%w 星期（0-6），星期天为星期的开始%W 一年中的星期数（00-53）星期一为星期的开始%x 本地相应的日期表示%X 本地相应的时间表示%Z 当前时区的名称%% %号本身

Third, datetime module

The datetime built-in object relationships are as follows:

Divided into Date/time/timedelta/tzinfo four classes, of which date, tzinfo and respectively have their own subclasses Datetim/timezone

1. Datetime.datetime.now () Gets the current time string

>>>datetime.datetime.now()2018-05-11 10:05:29.397237

2, Datetime.datetime.now (). Timestamp () Gets the current time timestamp

>>>datetime.datetime.now().timestamp()1526004460.797517

3, Datetime.datetime.today () Get current time month day

>>>datetime.datetime.today()2018-05-11

4. Some other methods

In [42]: #设置一个时间对象In [43]: d=datetime(2016,7,21,22,23,15)In [44]: #自定义格式显示In [45]: d.strftime(‘%x %X‘)Out[45]: ‘07/21/16 22:23:15‘In [46]: #显示英文格式In [47]: d.ctime()Out[47]: ‘Thu Jul 21 22:23:15 2016‘In [48]: #显示日历（年，年中第几周，周几）In [49]: d.isocalendar()Out[49]: (2016, 29, 4)

DateTime sub-module unit interval: datetime.resolution=1 microseconds.

The time interval for the date submodule is 1 days date.resolution=1 days

Time interval multiplied by one number, indicating a few days apart

>>>from datetime import date#现在时间是date.today()datetime.date(2018, 5, 11)#100天以前的日期是result=date.today()-date.resolution*100print(result)输出结果：2018-01-31

Python's use of time-and datetime-related modules