time和datetime模块

傷城~ 2021-09-20 01:46 528阅读 0赞

1.在Python中表示时间的方式

1.1时间戳

时间戳(timestamp)方式：通常来说，时间戳表示从1970年1月1日00:00:00开始按秒计算的偏移量。运行type(time.time())返回float类型
UTC （Coordinated Universal Time,世界协调时）即格林威治天文时间，世界标准时间。在中国为UTC+8。DST(Daylight Saving Time)即夏令时

import time
type(time.time())

print(time.time())
1557046718.6016247

1.2.格式化的时间字符串

“2019-05-05”

1.3.元组

元组(struct_time)方式共九个元素。返回struct_time的函数主要有gmtime(),localtime(),strptime()。下面列出这种方式元组中的几个元素

  1. 索引（Index）    属性（Attribute）    值（Values）
  2. 0     tm_year（年）                             比如2011 
  3. 1     tm_mon（月）                             1 - 12
  4. 2     tm_mday（日）                           1 - 31
  5. 3     tm_hour（时）                             0 - 23
  6. 4     tm_min（分）                               0 - 59
  7. 5     tm_sec（秒）                               0 - 61
  8. 6     tm_wday（weekday）                  0 - 6（0表示周日）
  9. 7     tm_yday（一年中的第几天）        1 - 366
  10. 8     tm_isdst（是否是夏令时）            默认为-1

2.time模块的方法

  • time.localtime([secs])：将一个时间戳转换为当前时区的struct_time。secs参数未提供，则以当前时间为准。

    time.localtime()
    time.struct_time(tm_year=2019, tm_mon=5, tm_mday=5, tm_hour=17, tm_min=15, tm_sec=43, tm_wday=6, tm
    _yday=125, tm_isdst=0)
    time.localtime()
    time.struct_time(tm_year=2019, tm_mon=4, tm_mday=25, tm_hour=23, tm_min=57, tm_sec=32, tm_wday=3, tm_yday=115, tm_isdst=0)
    a.tm_year
    2019
    ‘%s-%s-%s’%(a.tm_year,a.tm_mon,a.tm_mday)
    ‘2019-4-26’

  • time.gmtime([secs])：和localtime()方法类似，gmtime()方法是将一个时间戳转换为UTC时区（0时区）的struct_time。0时区的时间+8小时是utc+8的时间

    time.gmtime()
    time.structtime(tm_year=2019, tm_mon=5, tm_mday=5, tm_hour=9, tm_min=20, tm_sec=41, tm_wday=6, tm
    yday=125, tm_isdst=0)

  • time.time()：返回当前时间的时间戳。

    time.time()
    1557048269.2991927

  • time.mktime(t)：将一个struct_time转化为时间戳。

    time.mktime(time.localtime())
    1557048434.0

  • time.sleep(secs)：线程推迟指定的时间运行。单位为秒。

    time.sleep(2)

  • time.asctime([t])：把一个表示时间的元组或者struct_time表示为这种形式：’Sun Oct 1 12:04:38 2017’。如果没有参数，将会将time.localtime()作为参数传入。

    time.asctime(time.localtime())
    ‘Sun May 5 17:30:00 2019’

  • time.ctime([secs])：把一个时间戳（按秒计算的浮点数）转化为time.asctime()的形式。如果参数未给或者为None的时候，将会默认time.time()为参数。它的作用相当于time.asctime(time.localtime(secs))。

    time.ctime(time.time())
    ‘Sun May 5 17:34:26 2019’

  • time.strftime(format[, t])：把一个代表时间的元组或者struct_time（如由time.localtime()和time.gmtime()返回）转化为格式化的时间字符串。如果t未指定，将传入time.localtime()。

    time.strftime(“%Y-%m-%d %X”, time.localtime())
    ‘2019-05-05 17:37:35’

  • time.strptime(string[, format])：把一个格式化时间字符串转化为struct_time。实际上它和strftime()是逆操作。

    time.strptime(‘2019-05-05 17:37:35’, “%Y-%m-%d %X”)
    time.struct_time(tm_year=2019, tm_mon=5, tm_mday=5, tm_hour=17, tm_min=37, tm_sec=35, tm_wday=6, tm
    _yday=125, tm_isdst=-1)

time和datetime模块

字符串转时间格式对应表

  1. Meaning Notes
  2. %a  Locale’s abbreviated weekday name.  
  3. %A  Locale’s full weekday name. 
  4. %b  Locale’s abbreviated month name.    
  5. %B  Locale’s full month name.   
  6. %c  Locale’s appropriate date and time representation.  
  7. %d  Day of the month as a decimal number [01,31].   
  8. %H  Hour (24-hour clock) as a decimal number [00,23].   
  9. %I  Hour (12-hour clock) as a decimal number [01,12].   
  10. %j  Day of the year as a decimal number [001,366].  
  11. %m  Month as a decimal number [01,12].  
  12. %M  Minute as a decimal number [00,59]. 
  13. %p  Locale’s equivalent of either AM or PM. (1)
  14. %S  Second as a decimal number [00,61]. (2)
  15. %U  Week number of the year (Sunday as the first day of the week) as a decimal number [00,53]. All days in a new year preceding the first Sunday are considered to be in week 0.    (3)
  16. %w  Weekday as a decimal number [0(Sunday),6].  
  17. %W  Week number of the year (Monday as the first day of the week) as a decimal number [00,53]. All days in a new year preceding the first Monday are considered to be in week 0.    (3)
  18. %x  Locale’s appropriate date representation.   
  19. %X  Locale’s appropriate time representation.   
  20. %y  Year without century as a decimal number [00,99].   
  21. %Y  Year with century as a decimal number.  
  22. %z  Time zone offset indicating a positive or negative time difference from UTC/GMT of the form +HHMM or -HHMM, where H represents decimal hour digits and M represents decimal minute digits [-23:59, +23:59]. 
  23. %Z  Time zone name (no characters if no time zone exists).  
  24. %%  A literal '%' character.
  26. >>> time.strftime("%a",time.localtime())
  27. 'Sun'
  28. >>> time.strftime("%A",time.localtime())
  29. 'Sunday'
  30. >>> time.strftime("%b",time.localtime())
  31. 'May'
  32. >>> time.strftime("%B",time.localtime())
  33. 'May'
  34. >>> time.strftime("%c",time.localtime())
  35. 'Sun May  5 17:54:45 2019'
  36. >>> time.strftime("%C",time.localtime())
  37. '20'
  38. >>> time.strftime("%d",time.localtime())
  39. '05'
  40. >>> time.strftime("%D",time.localtime())
  41. '05/05/19'
  42. >>> time.strftime("%H",time.localtime())
  43. '17'
  44. >>> time.strftime("%h",time.localtime())
  45. 'May'
  46. >>> time.strftime("%I",time.localtime())
  47. '05'
  48. >>> time.strftime("%i",time.localtime())
  49. Traceback (most recent call last):
  50.   File "<stdin>", line 1, in <module>
  51. ValueError: Invalid format string
  52. >>> time.strftime("%j",time.localtime())
  53. '125'
  54. >>> time.strftime("%m",time.localtime())
  55. '05'
  56. >>> time.strftime("%M",time.localtime())
  57. '57'
  58. >>> time.strftime("%p",time.localtime())
  59. 'PM'
  60. >>> time.strftime("%S",time.localtime())
  61. '22'
  62. >>> time.strftime("%U",time.localtime())
  63. '18'
  64. >>> time.strftime("%W",time.localtime())
  65. '17'
  66. >>> time.strftime("%w",time.localtime())
  67. '0'
  68. >>> time.strftime("%x",time.localtime())
  69. '05/05/19'
  70. >>> time.strftime("%X",time.localtime())
  71. '17:58:54'
  72. >>> time.strftime("%y",time.localtime())
  73. '19'
  74. >>> time.strftime("%Y",time.localtime())
  75. '2019'
  76. >>> time.strftime("%Z",time.localtime())
  77. '?D1¨²¡À¨º¡Á?¨º¡À??'
  78. >>> time.strftime("%%",time.localtime())
  79. '%'
  80. >>>

3.datetime模块

  1. datetime.date：表示日期的类。常用的属性有year, month, day；
  2. datetime.time：表示时间的类。常用的属性有hour, minute, second, microsecond；
  3. datetime.datetime：表示日期时间。
  4. datetime.timedelta：表示时间间隔，即两个时间点之间的长度。
  5. datetime.tzinfo：与时区有关的相关信息。（这里不详细充分讨论该类,可以参考python手册）
  7. "需要记住的"
  8. 1.d=datetime.datetime.now() 返回当前的datetime日期类型
  9. d.timestamp(),d.today(), d.year,d.timetuple()等方法可以调用
  11. #!/usr/bin/env python
  12. # -*- coding:utf-8 -*-
  13. # Author: vita
  14. import datetime
  15. d = datetime.datetime.now()
  16. print(d)
  17. print("d.timestamp()",d.timestamp())
  18. print("d.today()",d.today())
  19. print("d.year",d.year)
  20. print("d.timetuple()",d.timetuple())
  22. E:\PythonProject\python-test\venvP3\Scripts\python.exe E:/PythonProject/python-test/BasicGrammer/test.py
  23. 2019-05-05 18:11:52.005561
  24. d.timestamp() 1557051112.005561
  25. d.today() 2019-05-05 18:11:52.005561
  26. d.year 2019
  27. d.timetuple() time.struct_time(tm_year=2019, tm_mon=5, tm_mday=5, tm_hour=18, tm_min=11, tm_sec=52, tm_wday=6, tm_yday=125, tm_isdst=-1)
  29. Process finished with exit code 0
  30. 2.datetime.date.fromtimestamp(时间戳)把时间戳转换为datetime日期类型
  31. >>> datetime.date.fromtimestamp(1557051112.005561)
  32. datetime.date(2019, 5, 5)
  33. 3.时间运算
  34. >>> datetime.datetime.now()
  36. datetime.datetime(2017, 10, 1, 12, 53, 11, 821218)
  38. >>> datetime.datetime.now() + datetime.timedelta(4) #当前时间 +4天
  40. datetime.datetime(2017, 10, 5, 12, 53, 35, 276589)
  42. >>> datetime.datetime.now() + datetime.timedelta(hours=4) #当前时间+4小时
  44. datetime.datetime(2017, 10, 1, 16, 53, 42, 876275)
  45. 4.时间替换
  46. #!/usr/bin/env python
  47. # -*- coding:utf-8 -*-
  48. # Author: vita
  49. import datetime
  50. d = datetime.datetime.now()
  52. print(d.replace(year=2020,month=11,day=30))
  54. print("d.timetuple()",d.timetuple())
  56. E:\PythonProject\python-test\venvP3\Scripts\python.exe E:/PythonProject/python-test/BasicGrammer/test.py
  57. 2020-11-30 18:16:59.517815
  58. d.timetuple() time.struct_time(tm_year=2019, tm_mon=5, tm_mday=5, tm_hour=18, tm_min=16, tm_sec=59, tm_wday=6, tm_yday=125, tm_isdst=-1)
  60. Process finished with exit code 0

转载于:https://blog.51cto.com/10983441/2389382

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    1.在Python中表示时间的方式 1.1时间戳 > 时间戳(timestamp)方式：通常来说，时间戳表示从1970年1月1日00:00:00开始按秒计算的偏移量

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