The most troublesome time for Python is medicine.

Https://www.cnblogs.com/sunshineyang/p/6818834.html

One: The time method used frequently

1. Get the current time

  uses the time module to first get the current timestamp in [Time.time]: +/-(): 1408066927.208922 converts the timestamp to a time tuple Struct_timein [43]: Time.localtime (Time.time ()) out[43]: Time.struct_time (tm_year=2014, tm_mon=8, tm_mday=15, tm_hour=9, tm_min=42, tm_ Sec=20, tm_wday=4, tm_yday=227, tm_isdst=0) format output desired time in []: Time.strftime ('%y-%m-%d%h:%m:%s ', Time.localtime ( Time.time ())) out[44]: ' 2014-08-15 09:43:04 ' next, without parameters, the default is to output the current time in []: Time.strftime ('%y-%m-%d%h:%m:%s ') out[48]: ' 2014-08-15-09:46:53 ' Of course, it can also be implemented through a DateTime module, as follows: in [time.time]: T = + () in []: Datetime.datetime.fromtimestamp (t). Strftime ('%y-%m-%d%h:%m:%s ') out[69]: ' 2014-08-15 10:04:51 ' Also, you can use only the DateTime module in []: Datetime.datetime.now (). Strftime ('%y-%m-%d%h:%m:%s ') out[46]: ' 2014-08-15 09:45:27 ' in []: Datetime.datetime.today (). Strftime ('%y-%m-%d%H: %m:%s ') out[47]: ' 2014-08-15 09:46:10 ' 
 
 2. Get the time difference, calculate the execution times of the program, and so on: 
  

使用time模块：In [75]: def t():   ....:     start = time.time()   ....:     time.sleep(10)   ....:     end = time.time()   ....:     print end - start   ....:In [76]: t()10.0014948845使用datetime模块：In [49]: starttime = datetime.datetime.now()In [50]: endtime = datetime.datetime.now()In [51]: print (endtime - starttime).seconds6

3. Calculate yesterday's date (divergent thinking, calculate other date addition, subtraction, etc.):

In [52]: d1 = datetime.datetime.now()In [53]: d2 = d1 - datetime.timedelta(days=1)In [54]: d1Out[54]: datetime.datetime(2014, 8, 15, 9, 54, 10, 68665)In [55]: d2Out[55]: datetime.datetime(2014, 8, 14, 9, 54, 10, 68665)

4. Time-tuple Struct_time converted to timestamp

In [56]: datetime.datetime.now()Out[56]: datetime.datetime(2014, 8, 15, 9, 57, 52, 779893)In [57]: datetime.datetime.now().timetuple()Out[57]: time.struct_time(tm_year=2014, tm_mon=8, tm_mday=15, tm_hour=9, tm_min=58, tm_sec=12, tm_wday=4, tm_yday=227, tm_isdst=-1)In [58]: time.mktime(datetime.datetime.now().timetuple())Out[58]: 1408067904.0


5.strptime is also useful for converting a time string to a time tuple struct_time

In [73]: time.strftime(‘%Y-%m-%d %H:%M:%S‘)Out[73]: ‘2014-08-15 10:27:36‘In [74]: time.strptime(‘2014-08-15 10:27:36‘,‘%Y-%m-%d %H:%M:%S‘)Out[74]: time.struct_time(tm_year=2014, tm_mon=8, tm_mday=15, tm_hour=10, tm_min=27, tm_sec=36, tm_wday=4, tm_yday=227, tm_isdst=-1)

# #二: Introduction to common methods of time and DateTime modules

Two ways to represent time:

1. 时间戳(相对于1970.1.1 00:00:00以秒计算的偏移量),时间戳是惟一的2. 时间元组 即(struct_time),共有九个元素，分别表示，同一个时间戳的struct_time会因为时区不同而不同

A few common methods of time module

1.time.clock ()

这个需要注意，在不同的系统上含义不同。在UNIX系统上，它返回的是“进程时间”，它是用秒表示的浮点数（时间 戳）。而在WINDOWS中，第一次调用，返回的是进程运行的实际时间。而第二次之后的调用是自第一次调用以后到现在的运行时间。（实际上是以WIN32 上QueryPerformanceCounter()为基础，它比毫秒表示更为精确）[email protected]:/tmp$ cat clock.py#!/usr/bin/env pythonimport timeif __name__ == ‘__main__‘:    time.sleep(1)    print "clock1:%s" % time.clock()    time.sleep(1)    print "clock2:%s" % time.clock()    time.sleep(1)    print "clock3:%s" % time.clock()运行脚本：[email protected]:/tmp$ ./clock.pyclock1:0.059173clock2:0.059299clock3:0.059416

2.time.sleep (secs)

线程推迟指定的时间运行适合放在脚本里，定时sleep一会然后继续干啥In [138]: while True:   .....:     time.sleep(3)   .....:     print time.strftime(‘%H:%M:%S‘)   .....:17:21:3517:21:3817:21:4117:21:44……

3.time.localtime ([secs])

将一个时间戳转换成一个当前时区的struct_time，如果seconds参数未输入，则以当前时间为转换标准未提供secs参数时，按当前时间为准In [141]: time.localtime()Out[141]: time.struct_time(tm_year=2014, tm_mon=8, tm_mday=14, tm_hour=17, tm_min=23, tm_sec=48, tm_wday=3, tm_yday=226, tm_isdst=0)提供secs为当前时间戳时In [142]: time.time()Out[142]: 1408008232.217969In [143]: time.localtime(time.time())Out[143]: time.struct_time(tm_year=2014, tm_mon=8, tm_mday=14, tm_hour=17, tm_min=24, tm_sec=2, tm_wday=3, tm_yday=226, tm_isdst=0)

4.time.strftime (format[, T])

将指定的struct_time(默认为当前时间)，根据指定的格式化字符串输出t未指定，传入time.localtime()作为默认参数：In [156]: time.strftime(‘%Y-%m-%d %H:%M:%S‘)Out[156]: ‘2014-08-14 17:28:16’指定t为time.localtime(1407945600.0)时：In [157]: time.localtime(1407945600.0)Out[157]: time.struct_time(tm_year=2014, tm_mon=8, tm_mday=14, tm_hour=0, tm_min=0, tm_sec=0, tm_wday=3, tm_yday=226, tm_isdst=0)In [158]: time.strftime(‘%Y-%m-%d %H:%M:%S‘,time.localtime(1407945600.0))Out[158]: ‘2014-08-14 00:00:00’

5.time.time ()

返回当前时间的时间戳In [161]: time.time()Out[161]: 1408008711.730218

6.time.mktime (t)

将一个struct_time转换为时间戳,如下time.localtime接收一个时间戳返回一个struct_time，而time.mktime接收一个struct_time，返回一个时间戳In [159]: time.localtime(1407945600.0)Out[159]: time.struct_time(tm_year=2014, tm_mon=8, tm_mday=14, tm_hour=0, tm_min=0, tm_sec=0, tm_wday=3, tm_yday=226, tm_isdst=0)In [160]: time.mktime(time.localtime(1407945600.0))Out[160]: 1407945600.0残阳似血的博客：

# Common methods of #datetime module

The most common types of datetime modules are the following four classes:

1. datetime.date: 是指年月日构成的日期(相当于日历)2. datetime.time: 是指时分秒微秒构成的一天24小时中的具体时间(相当于手表)3. datetime.datetime: 上面两个合在一起，既包含时间又包含日期4. datetime.timedelta: 时间间隔对象(timedelta)。一个时间点(datetime)加上一个时间间隔(timedelta)可以得到一个新的时间点(datetime)。比如今天的上午3点加上5个小时得到今天的上午8点。同理，两个时间点相减会得到一个时间间隔。

1.datetime.date class

  1. Create a new Date object that can either call Datetime.date.today () directly or directly to Datetime.date (), as follows: in [4]: Today = Datetime.date.today () in [5]: Todayout[5]: datetime.date (8, +) in [6]: t = datetime.date (2014,8,15) in [7]: Tout[7]: D Atetime.date (8, 2.datetime.date.strftime) format to take time, such as the usual "year-month-day hours: minutes: Seconds" format in [8]: today.strftime ('%y- %m-%d%h:%m:%s ') out[8]: ' 2014-08-15 00:00:00 ' Date object in hours, minutes, seconds default is 0, that that time 3.datetime.date.timple () into struct_time format, After this is passed to Time.mktime (t), it is converted directly into timestamp format in [9]: Today.timetuple () out[9]: Time.struct_time (tm_year=2014, tm_mon=8, tm_mday=15, Tm_hour=0, Tm_min=0, tm_sec=0, tm_wday=4, tm_yday=227, Tm_isdst=-1) in [ten]: Time.mktime (Today.timetuple ()) Out[10]: 1408032000.04.datetime.date.replace (year, month, day) returns a replaced Date object in [all]: Today.replace (year=2013) out[11]: Datetime.date (8, 5.datetime.date.fromtimestamp) converts the timestamp to a Date object in [12]: Datetime.date.fromtimestamp (1408058729) out[12]: datetime.date (8, +)  
 
 
 

2.datetime.time class

1.新建一个time对象In [15]: tOut[15]: datetime.time(8, 45, 20)2.datetime.time.(format)格式化输出In [16]: t.strftime(‘%Y-%m-%d %H:%M:%S‘)Out[16]: ‘1900-01-01 08:45:20’time对应的年、月、日为1900、01、01，纪元年的那个时间3.datetime.time.replace([hour[, minute[, second[, microsecond[, tzinfo]]]]]) 返回一个替换后的time对象In [17]: t.replace(hour=9)Out[17]: datetime.time(9, 45, 20)

3.datetime.datetime class

In fact, and the date of those methods, probably look at the following, briefly say 1. Create a new DateTime object with the date today, either directly calling Datetime.datetime.today () or directly to Datetime.datetime () , as follows: in [+]: D1 = Datetime.datetime.today () in [all]: d1out[22]: Datetime.datetime (8, 8, A, A, 790945) in []: D 2 = Datetime.datetime (8, 8, 790945) in []: d2out[24]: Datetime.datetime (2014, 8, 15, 8, 12, 34, 790945) 2.datetime.datetime.now ([TZ]) When you do not specify a time zone, and Datetime.datetime.today () are the same results as in [+]: Datetime.datetime.now () out[25]: Datetime.datetime (8, 8, 738672) 3..datetime.datetime.strftime (format) formatted to take time, such as "year-month-day hours: minutes: Seconds" Format in [d1out[27]: Datetime.datetime (8, 8, A, 790945) in []: D1.strftime ('%y-%m-%d%h:%m:%s ') out[28]: ' 2014-08-15 08:12:34 ' 4.datetime.datetime.timple () into the struct_time format, which is passed to Time.mktime (t) and then directly into timestamp format in []: d1out[29]: Datetime.datetime (8, 8, 790945) in [+]: D1.timetuple () out[30]: Time.struct_time (tm_year=2014, tm_mon=8 , tm_mday=15, Tm_hour=8, tm_min=12, tm_sec=34, tm_wday=4, tm_yday=227, Tm_isdst=-1) in [to]: Time.mktime (D1.timetuple ()) out[31]: 1408061554.05.datetime.datetime.replace ( Year, month, day) returns a substituted Date object in [[+]: d1out[32]: Datetime.datetime (8, 8, 790945, D1.replace) in [] year=2000) out[33]: Datetime.datetime (8, 8, 790945) 6.datetime.datetime.fromtimestamp (timestamp) Convert timestamp to DateTime object in [Time.time]: out[34 []: 1408061894.081552In []: Datetime.datetime.fromtimestamp (1408061894) OUT[35]: Datetime.datetime (2014, 8, 15, 8, 18, 14)

4.datetime.timedelta class

没啥好说的，主要做时间的加减法用，如下：In [78]: today = datetime.datetime.today()In [79]: yesterday = today - datetime.timedelta(days=1)In [80]: yesterdayOut[80]: datetime.datetime(2014, 8, 14, 15, 8, 25, 783471)In [81]: todayOut[81]: datetime.datetime(2014, 8, 15, 15, 8, 25, 783471)

The most troublesome time for Python is medicine.