2.3 版新增。
The datetime module supplies classes for manipulating dates and times in both simple and complex ways. While date and time arithmetic is supported, the focus of the implementation is on efficient attribute extraction for output formatting and manipulation. For related functionality, see also the time and calendar 模块。
There are two kinds of date and time objects: “naive” and “aware”.
An aware object has sufficient knowledge of applicable algorithmic and political time adjustments, such as time zone and daylight saving time information, to locate itself relative to other aware objects. An aware object is used to represent a specific moment in time that is not open to interpretation [1] .
A naive object does not contain enough information to unambiguously locate itself relative to other date/time objects. Whether a naive object represents Coordinated Universal Time (UTC), local time, or time in some other timezone is purely up to the program, just like it’s up to the program whether a particular number represents metres, miles, or mass. Naive objects are easy to understand and to work with, at the cost of ignoring some aspects of reality.
For applications requiring aware objects, datetime and time objects have an optional time zone information attribute, tzinfo , that can be set to an instance of a subclass of the abstract tzinfo class. These tzinfo objects capture information about the offset from UTC time, the time zone name, and whether Daylight Saving Time is in effect. Note that no concrete tzinfo classes are supplied by the datetime module. Supporting timezones at whatever level of detail is required is up to the application. The rules for time adjustment across the world are more political than rational, and there is no standard suitable for every application.
The datetime 模块导出下列常量：
另请参阅
An idealized time, independent of any particular day, assuming that every day has exactly 24*60*60 seconds (there is no notion of “leap seconds” here). Attributes: hour , minute , second , microsecond ，和 tzinfo .
A combination of a date and a time. Attributes: year , month , day , hour , minute , second , microsecond ，和 tzinfo .
A duration expressing the difference between two date , time ，或 datetime instances to microsecond resolution.
An abstract base class for time zone information objects. These are used by the datetime and time classes to provide a customizable notion of time adjustment (for example, to account for time zone and/or daylight saving time).
这些类型的对象是不可变的。
对象的 date 类型始终是单纯的。
An object of type time or datetime may be naive or aware. A datetime 对象 d is aware if d.tzinfo 不是 None and d.tzinfo.utcoffset(d) 不返回 None 。若 d.tzinfo is None ，或者若 d.tzinfo 不是 None but d.tzinfo.utcoffset(d) 返回 None , d is naive. A time 对象 t is aware if t.tzinfo 不是 None and t.tzinfo.utcoffset(None) 不返回 None 。否则， t 是单纯的。
The distinction between naive and aware doesn’t apply to timedelta 对象。
子类关系：
对象
timedelta
tzinfo
time
date
datetime
A timedelta 对象表示持续时间，2 日期 (或时间) 之间的差异。
所有自变量是可选的且默认为 0 . Arguments may be ints, longs, or floats, and may be positive or negative.
仅 days , seconds and microseconds 被存储在内部。自变量转换成这些单位：
然后规范化 days、seconds 和 microseconds (微秒) 以便表示唯一，按
If any argument is a float and there are fractional microseconds, the fractional microseconds left over from all arguments are combined and their sum is rounded to the nearest microsecond. If no argument is a float, the conversion and normalization processes are exact (no information is lost).
If the normalized value of days lies outside the indicated range, OverflowError 被引发。
Note that normalization of negative values may be surprising at first. For example,
>>> from datetime import timedelta >>> d = timedelta(microseconds=-1) >>> (d.days, d.seconds, d.microseconds) (-1, 86399, 999999)
类属性：
最大正值 timedelta 对象， timedelta(days=999999999, hours=23, minutes=59, seconds=59, microseconds=999999) .
注意，由于规范化， timedelta.max > -timedelta.min . -timedelta.max 不可表示按 timedelta 对象。
实例属性 (只读)：
| 属性 | 值 |
|---|---|
| days | 介于 -99999999999 和 999999999 (包括在内) 之间 |
| seconds | 介于 0 和 86399 (包括在内) 之间 |
| microseconds | 介于 0 和 999999 (包括在内) 之间 |
支持的操作：
| 操作 | 结果 |
|---|---|
| t1 = t2 + t3 | Sum of t2 and t3 . Afterwards t1 - t2 == t3 and t1 - t3 == t2 are true. (1) |
| t1 = t2 - t3 | Difference of t2 and t3 . Afterwards t1 == t2 - t3 and t2 == t1 + t3 are true. (1) |
| t1 = t2 * i or t1 = i * t2 | Delta multiplied by an integer or long. Afterwards t1 // i == t2 为 True， provided i != 0 . |
| 一般而言， t1 * i == t1 * (i-1) + t1 为 True。(1) | |
| t1 = t2 // i | The floor is computed and the remainder (if any) is thrown away. (3) |
| +t1 | 返回 timedelta 对象采用 same value. (2) |
| -t1 | 相当于 timedelta (- t1.days , - t1.seconds , - t1.microseconds ), and to t1 * -1. (1)(4) |
| abs(t) | 相当于 + t 当 t.days >= 0 ，和 to - t 当 t.days < 0 . (2) |
| str(t) | Returns a string in the form [D day[s], ][H]H:MM:SS[.UUUUUU] , where D is negative for negative t . (5) |
| repr(t) | Returns a string in the form datetime.timedelta(D[, S[, U]]) , where D is negative for negative t . (5) |
注意事项：
This is exact, but may overflow.
This is exact, and cannot overflow.
除以 0 引发 ZeroDivisionError .
- timedelta.max 不可表示按 timedelta 对象。
String representations of timedelta objects are normalized similarly to their internal representation. This leads to somewhat unusual results for negative timedeltas. For example:
>>> timedelta(hours=-5) datetime.timedelta(-1, 68400) >>> print(_) -1 day, 19:00:00
In addition to the operations listed above timedelta objects support certain additions and subtractions with date and datetime 对象 (见下文)。
比较 timedelta objects are supported with the timedelta object representing the smaller duration considered to be the smaller timedelta. In order to stop mixed-type comparisons from falling back to the default comparison by object address, when a timedelta object is compared to an object of a different type, TypeError is raised unless the comparison is == or != . The latter cases return False or True ，分别。
timedelta 对象是 hashable (usable as dictionary keys), support efficient pickling, and in Boolean contexts, a timedelta object is considered to be true if and only if it isn’t equal to timedelta(0) .
实例方法：
Return the total number of seconds contained in the duration. Equivalent to (td.microseconds + (td.seconds + td.days * 24 * 3600) * 10**6) / 10**6 computed with true division enabled.
Note that for very large time intervals (greater than 270 years on most platforms) this method will lose microsecond accuracy.
2.7 版新增。
用法范例：
>>> from datetime import timedelta >>> year = timedelta(days=365) >>> another_year = timedelta(weeks=40, days=84, hours=23, ... minutes=50, seconds=600) # adds up to 365 days >>> year.total_seconds() 31536000.0 >>> year == another_year True >>> ten_years = 10 * year >>> ten_years, ten_years.days // 365 (datetime.timedelta(3650), 10) >>> nine_years = ten_years - year >>> nine_years, nine_years.days // 365 (datetime.timedelta(3285), 9) >>> three_years = nine_years // 3; >>> three_years, three_years.days // 365 (datetime.timedelta(1095), 3) >>> abs(three_years - ten_years) == 2 * three_years + year True
A date object represents a date (year, month and day) in an idealized calendar, the current Gregorian calendar indefinitely extended in both directions. January 1 of year 1 is called day number 1, January 2 of year 1 is called day number 2, and so on. This matches the definition of the “proleptic Gregorian” calendar in Dershowitz and Reingold’s book Calendrical Calculations, where it’s the base calendar for all computations. See the book for algorithms for converting between proleptic Gregorian ordinals and many other calendar systems.
All arguments are required. Arguments may be ints or longs, in the following ranges:
若给定自变量在那些范围之外， ValueError 被引发。
其它构造函数，所有类方法：
Return the current local date. This is equivalent to date.fromtimestamp(time.time()) .
Return the local date corresponding to the POSIX timestamp, such as is returned by time.time() . This may raise ValueError , if the timestamp is out of the range of values supported by the platform C localtime() function. It’s common for this to be restricted to years from 1970 through 2038. Note that on non-POSIX systems that include leap seconds in their notion of a timestamp, leap seconds are ignored by fromtimestamp() .
Return the date corresponding to the proleptic Gregorian ordinal, where January 1 of year 1 has ordinal 1. ValueError 被引发除非 1 <= ordinal <= date.max.toordinal() 。对于任何日期 d , date.fromordinal(d.toordinal()) == d .
类属性：
最早可表示日期， date(MINYEAR, 1, 1) .
最新可表示日期， date(MAXYEAR, 12, 31) .
The smallest possible difference between non-equal date objects, timedelta(days=1) .
实例属性 (只读)：
在 1 至 12 (包括在内) 之间。
Between 1 and the number of days in the given month of the given year.
支持的操作：
| 操作 | 结果 |
|---|---|
| date2 = date1 + timedelta | date2 is timedelta.days days removed from date1 . (1) |
| date2 = date1 - timedelta | 计算 date2 这样 date2 + timedelta == date1 . (2) |
| timedelta = date1 - date2 | (3) |
| date1 < date2 | date1 被认为小于 date2 当 date1 precedes date2 in time. (4) |
注意事项：
Dates can be used as dictionary keys. In Boolean contexts, all date 对象被认为是 True。
实例方法：
Return a date with the same value, except for those parameters given new values by whichever keyword arguments are specified. For example, if d == date(2002, 12, 31) ，那么 d.replace(day=26) == date(2002, 12, 26) .
返回 time.struct_time 譬如返回通过 time.localtime() . The hours, minutes and seconds are 0, and the DST flag is -1. d.timetuple() 相当于 time.struct_time((d.year, d.month, d.day, 0, 0, 0, d.weekday(), yday, -1)) ，其中 yday = d.toordinal() - date(d.year, 1, 1).toordinal() + 1 is the day number within the current year starting with 1 for January 1st.
Return the proleptic Gregorian ordinal of the date, where January 1 of year 1 has ordinal 1. For any date 对象 d , date.fromordinal(d.toordinal()) == d .
Return the day of the week as an integer, where Monday is 0 and Sunday is 6. For example, date(2002, 12, 4).weekday() == 2 , a Wednesday. See also isoweekday() .
Return the day of the week as an integer, where Monday is 1 and Sunday is 7. For example, date(2002, 12, 4).isoweekday() == 3 , a Wednesday. See also weekday() , isocalendar() .
Return a 3-tuple, (ISO year, ISO week number, ISO weekday).
The ISO calendar is a widely used variant of the Gregorian calendar. See http://www.staff.science.uu.nl/~gent0113/calendar/isocalendar.htm for a good explanation.
The ISO year consists of 52 or 53 full weeks, and where a week starts on a Monday and ends on a Sunday. The first week of an ISO year is the first (Gregorian) calendar week of a year containing a Thursday. This is called week number 1, and the ISO year of that Thursday is the same as its Gregorian year.
For example, 2004 begins on a Thursday, so the first week of ISO year 2004 begins on Monday, 29 Dec 2003 and ends on Sunday, 4 Jan 2004, so that date(2003, 12, 29).isocalendar() == (2004, 1, 1) and date(2004, 1, 4).isocalendar() == (2004, 1, 7) .
Return a string representing the date in ISO 8601 format, ‘YYYY-MM-DD’. For example, date(2002, 12, 4).isoformat() == '2002-12-04' .
对于日期 d , str(d) 相当于 d.isoformat() .
Return a string representing the date, for example date(2002, 12, 4).ctime() == 'Wed Dec 4 00:00:00 2002' . d.ctime() 相当于 time.ctime(time.mktime(d.timetuple())) on platforms where the native C ctime() function (which time.ctime() invokes, but which date.ctime() does not invoke) conforms to the C standard.
Return a string representing the date, controlled by an explicit format string. Format codes referring to hours, minutes or seconds will see 0 values. For a complete list of formatting directives, see section strftime() 和 strptime() 行为 .
如同 date.strftime() . This makes it possible to specify format string for a date object when using str.format() . See section strftime() 和 strptime() 行为 .
计算事件天数的范例：
>>> import time >>> from datetime import date >>> today = date.today() >>> today datetime.date(2007, 12, 5) >>> today == date.fromtimestamp(time.time()) True >>> my_birthday = date(today.year, 6, 24) >>> if my_birthday < today: ... my_birthday = my_birthday.replace(year=today.year + 1) >>> my_birthday datetime.date(2008, 6, 24) >>> time_to_birthday = abs(my_birthday - today) >>> time_to_birthday.days 202
Example of working with date :
>>> from datetime import date >>> d = date.fromordinal(730920) # 730920th day after 1. 1. 0001 >>> d datetime.date(2002, 3, 11) >>> t = d.timetuple() >>> for i in t: ... print i 2002 # year 3 # month 11 # day 0 0 0 0 # weekday (0 = Monday) 70 # 70th day in the year -1 >>> ic = d.isocalendar() >>> for i in ic: ... print i 2002 # ISO year 11 # ISO week number 1 # ISO day number ( 1 = Monday ) >>> d.isoformat() '2002-03-11' >>> d.strftime("%d/%m/%y") '11/03/02' >>> d.strftime("%A %d. %B %Y") 'Monday 11. March 2002' >>> 'The {1} is {0:%d}, the {2} is {0:%B}.'.format(d, "day", "month") 'The day is 11, the month is March.'
A datetime object is a single object containing all the information from a date object and a time object. Like a date 对象， datetime assumes the current Gregorian calendar extended in both directions; like a time object, datetime assumes there are exactly 3600*24 seconds in every day.
构造函数：
The year, month and day arguments are required. tzinfo 可以是 None , or an instance of a tzinfo subclass. The remaining arguments may be ints or longs, in the following ranges:
若给定自变量在那些范围之外， ValueError 被引发。
其它构造函数，所有类方法：
Return the current local datetime, with tzinfo None 。这相当于 datetime.fromtimestamp(time.time()) 。另请参阅 now() , fromtimestamp() .
Return the current local date and time. If optional argument tz is None or not specified, this is like today() , but, if possible, supplies more precision than can be gotten from going through a time.time() timestamp (for example, this may be possible on platforms supplying the C gettimeofday() 函数)。
Else tz must be an instance of a class tzinfo subclass, and the current date and time are converted to tz ‘s time zone. In this case the result is equivalent to tz.fromutc(datetime.utcnow().replace(tzinfo=tz)) 。另请参阅 today() , utcnow() .
Return the current UTC date and time, with tzinfo None . This is like now() , but returns the current UTC date and time, as a naive datetime object. See also now() .
Return the local date and time corresponding to the POSIX timestamp, such as is returned by time.time() . If optional argument tz is None or not specified, the timestamp is converted to the platform’s local date and time, and the returned datetime object is naive.
Else tz must be an instance of a class tzinfo subclass, and the timestamp is converted to tz ‘s time zone. In this case the result is equivalent to tz.fromutc(datetime.utcfromtimestamp(timestamp).replace(tzinfo=tz)) .
fromtimestamp() 可能引发 ValueError , if the timestamp is out of the range of values supported by the platform C localtime() or gmtime() functions. It’s common for this to be restricted to years in 1970 through 2038. Note that on non-POSIX systems that include leap seconds in their notion of a timestamp, leap seconds are ignored by fromtimestamp() , and then it’s possible to have two timestamps differing by a second that yield identical datetime objects. See also utcfromtimestamp() .
Return the UTC datetime corresponding to the POSIX timestamp, with tzinfo None . This may raise ValueError , if the timestamp is out of the range of values supported by the platform C gmtime() function. It’s common for this to be restricted to years in 1970 through 2038. See also fromtimestamp() .
返回 datetime corresponding to the proleptic Gregorian ordinal, where January 1 of year 1 has ordinal 1. ValueError 被引发除非 1 <= ordinal <= datetime.max.toordinal() . The hour, minute, second and microsecond of the result are all 0, and tzinfo is None .
返回新的 datetime object whose date components are equal to the given date object’s, and whose time components and tzinfo attributes are equal to the given time object’s. For any datetime 对象 d , d == datetime.combine(d.date(), d.timetz()) . If date is a datetime object, its time components and tzinfo attributes are ignored.
返回 datetime 对应 date_string , parsed according to format 。这相当于 datetime(*(time.strptime(date_string, format)[0:6])) . ValueError is raised if the date_string and format can’t be parsed by time.strptime() or if it returns a value which isn’t a time tuple. For a complete list of formatting directives, see section strftime() 和 strptime() 行为 .
2.5 版新增。
类属性：
The latest representable datetime , datetime(MAXYEAR, 12, 31, 23, 59, 59, 999999, tzinfo=None) .
实例属性 (只读)：
在 1 至 12 (包括在内) 之间。
Between 1 and the number of days in the given month of the given year.
在 range(24) .
在 range(60) .
在 range(60) .
在 range(1000000) .
The object passed as the tzinfo 自变量到 datetime constructor, or None if none was passed.
支持的操作：
| 操作 | 结果 |
|---|---|
| datetime2 = datetime1 + timedelta | (1) |
| datetime2 = datetime1 - timedelta | (2) |
| timedelta = datetime1 - datetime2 | (3) |
| datetime1 < datetime2 | 比较 datetime to datetime . (4) |
datetime2 is a duration of timedelta removed from datetime1, moving forward in time if timedelta.days > 0, or backward if timedelta.days < 0. The result has the same tzinfo attribute as the input datetime, and datetime2 - datetime1 == timedelta after. OverflowError is raised if datetime2.year would be smaller than MINYEAR 或大于 MAXYEAR . Note that no time zone adjustments are done even if the input is an aware object.
Computes the datetime2 such that datetime2 + timedelta == datetime1. As for addition, the result has the same tzinfo attribute as the input datetime, and no time zone adjustments are done even if the input is aware. This isn’t quite equivalent to datetime1 + (-timedelta), because -timedelta in isolation can overflow in cases where datetime1 - timedelta does not.
Subtraction of a datetime 从 datetime is defined only if both operands are naive, or if both are aware. If one is aware and the other is naive, TypeError 被引发。
If both are naive, or both are aware and have the same tzinfo attribute, the tzinfo attributes are ignored, and the result is a timedelta 对象 t 这样 datetime2 + t == datetime1 . No time zone adjustments are done in this case.
If both are aware and have different tzinfo attributes, a-b acts as if a and b were first converted to naive UTC datetimes first. The result is (a.replace(tzinfo=None) - a.utcoffset()) - (b.replace(tzinfo=None) - b.utcoffset()) except that the implementation never overflows.
datetime1 被认为小于 datetime2 当 datetime1 precedes datetime2 in time.
If one comparand is naive and the other is aware, TypeError is raised. If both comparands are aware, and have the same tzinfo attribute, the common tzinfo attribute is ignored and the base datetimes are compared. If both comparands are aware and have different tzinfo attributes, the comparands are first adjusted by subtracting their UTC offsets (obtained from self.utcoffset() ).
注意
In order to stop comparison from falling back to the default scheme of comparing object addresses, datetime comparison normally raises TypeError if the other comparand isn’t also a datetime object. However, NotImplemented is returned instead if the other comparand has a timetuple() attribute. This hook gives other kinds of date objects a chance at implementing mixed-type comparison. If not, when a datetime object is compared to an object of a different type, TypeError is raised unless the comparison is == or != . The latter cases return False or True ，分别。
datetime objects can be used as dictionary keys. In Boolean contexts, all datetime 对象被认为是 True。
实例方法：
返回 time object with same hour, minute, second and microsecond. tzinfo is None . See also method timetz() .
返回 time object with same hour, minute, second, microsecond, and tzinfo attributes. See also method time() .
Return a datetime with the same attributes, except for those attributes given new values by whichever keyword arguments are specified. Note that tzinfo=None can be specified to create a naive datetime from an aware datetime with no conversion of date and time data.
返回 datetime object with new tzinfo 属性 tz , adjusting the date and time data so the result is the same UTC time as self , but in tz ‘s local time.
tz must be an instance of a tzinfo subclass, and its utcoffset() and dst() methods must not return None . self must be aware ( self.tzinfo 不得为 None ，和 self.utcoffset() must not return None ).
若 self.tzinfo is tz , self.astimezone(tz) 等于 self : no adjustment of date or time data is performed. Else the result is local time in time zone tz , representing the same UTC time as self : after astz = dt.astimezone(tz) , astz - astz.utcoffset() will usually have the same date and time data as dt - dt.utcoffset() . The discussion of class tzinfo explains the cases at Daylight Saving Time transition boundaries where this cannot be achieved (an issue only if tz models both standard and daylight time).
If you merely want to attach a time zone object tz to a datetime dt without adjustment of date and time data, use dt.replace(tzinfo=tz) . If you merely want to remove the time zone object from an aware datetime dt without conversion of date and time data, use dt.replace(tzinfo=None) .
Note that the default tzinfo.fromutc() method can be overridden in a tzinfo subclass to affect the result returned by astimezone() . Ignoring error cases, astimezone() acts like:
def astimezone(self, tz): if self.tzinfo is tz: return self # Convert self to UTC, and attach the new time zone object. utc = (self - self.utcoffset()).replace(tzinfo=tz) # Convert from UTC to tz's local time. return tz.fromutc(utc)
若 tzinfo is None ，返回 None , else returns self.tzinfo.utcoffset(self) , and raises an exception if the latter doesn’t return None ，或 timedelta object representing a whole number of minutes with magnitude less than one day.
若 tzinfo is None ，返回 None , else returns self.tzinfo.dst(self) , and raises an exception if the latter doesn’t return None ，或 timedelta object representing a whole number of minutes with magnitude less than one day.
若 tzinfo is None ，返回 None , else returns self.tzinfo.tzname(self) , raises an exception if the latter doesn’t return None or a string object,
返回 time.struct_time 譬如返回通过 time.localtime() . d.timetuple() 相当于 time.struct_time((d.year, d.month, d.day, d.hour, d.minute, d.second, d.weekday(), yday, dst)) ，其中 yday = d.toordinal() - date(d.year, 1, 1).toordinal() + 1 is the day number within the current year starting with 1 for January 1st. The tm_isdst flag of the result is set according to the dst() 方法： tzinfo is None or dst() 返回 None , tm_isdst 被设为 -1 ；否则若 dst() 返回非 0 值， tm_isdst 被设为 1 ；否则 tm_isdst 被设为 0 .
若 datetime 实例 d is naive, this is the same as d.timetuple() 除了 tm_isdst is forced to 0 regardless of what d.dst() returns. DST is never in effect for a UTC time.
若 d is aware, d is normalized to UTC time, by subtracting d.utcoffset() ，和 time.struct_time for the normalized time is returned. tm_isdst is forced to 0. Note that the result’s tm_year member may be MINYEAR -1 or MAXYEAR +1, if d .year was MINYEAR or MAXYEAR and UTC adjustment spills over a year boundary.
Return the proleptic Gregorian ordinal of the date. The same as self.date().toordinal() .
Return the day of the week as an integer, where Monday is 0 and Sunday is 6. The same as self.date().weekday() 。另请参阅 isoweekday() .
Return the day of the week as an integer, where Monday is 1 and Sunday is 7. The same as self.date().isoweekday() 。另请参阅 weekday() , isocalendar() .
Return a 3-tuple, (ISO year, ISO week number, ISO weekday). The same as self.date().isocalendar() .
Return a string representing the date and time in ISO 8601 format, YYYY-MM-DDTHH:MM:SS.mmmmmm or, if microsecond is 0, YYYY-MM-DDTHH:MM:SS
若 utcoffset() 不返回 None , a 6-character string is appended, giving the UTC offset in (signed) hours and minutes: YYYY-MM-DDTHH:MM:SS.mmmmmm+HH:MM or, if microsecond is 0 YYYY-MM-DDTHH:MM:SS+HH:MM
可选自变量 sep (默认 'T' ) is a one-character separator, placed between the date and time portions of the result. For example,
>>> from datetime import tzinfo, timedelta, datetime >>> class TZ(tzinfo): ... def utcoffset(self, dt): return timedelta(minutes=-399) ... >>> datetime(2002, 12, 25, tzinfo=TZ()).isoformat(' ') '2002-12-25 00:00:00-06:39'
Return a string representing the date and time, for example datetime(2002, 12, 4, 20, 30, 40).ctime() == 'Wed Dec 4 20:30:40 2002' . d.ctime() 相当于 time.ctime(time.mktime(d.timetuple())) on platforms where the native C ctime() function (which time.ctime() invokes, but which datetime.ctime() does not invoke) conforms to the C standard.
Return a string representing the date and time, controlled by an explicit format string. For a complete list of formatting directives, see section strftime() 和 strptime() 行为 .
如同 datetime.strftime() . This makes it possible to specify format string for a datetime object when using str.format() . See section strftime() 和 strptime() 行为 .
Examples of working with datetime objects:
>>> from datetime import datetime, date, time >>> # Using datetime.combine() >>> d = date(2005, 7, 14) >>> t = time(12, 30) >>> datetime.combine(d, t) datetime.datetime(2005, 7, 14, 12, 30) >>> # Using datetime.now() or datetime.utcnow() >>> datetime.now() datetime.datetime(2007, 12, 6, 16, 29, 43, 79043) # GMT +1 >>> datetime.utcnow() datetime.datetime(2007, 12, 6, 15, 29, 43, 79060) >>> # Using datetime.strptime() >>> dt = datetime.strptime("21/11/06 16:30", "%d/%m/%y %H:%M") >>> dt datetime.datetime(2006, 11, 21, 16, 30) >>> # Using datetime.timetuple() to get tuple of all attributes >>> tt = dt.timetuple() >>> for it in tt: ... print it ... 2006 # year 11 # month 21 # day 16 # hour 30 # minute 0 # second 1 # weekday (0 = Monday) 325 # number of days since 1st January -1 # dst - method tzinfo.dst() returned None >>> # Date in ISO format >>> ic = dt.isocalendar() >>> for it in ic: ... print it ... 2006 # ISO year 47 # ISO week 2 # ISO weekday >>> # Formatting datetime >>> dt.strftime("%A, %d. %B %Y %I:%M%p") 'Tuesday, 21. November 2006 04:30PM' >>> 'The {1} is {0:%d}, the {2} is {0:%B}, the {3} is {0:%I:%M%p}.'.format(dt, "day", "month", "time") 'The day is 21, the month is November, the time is 04:30PM.'
Using datetime with tzinfo:
>>> from datetime import timedelta, datetime, tzinfo >>> class GMT1(tzinfo): ... def utcoffset(self, dt): ... return timedelta(hours=1) + self.dst(dt) ... def dst(self, dt): ... # DST starts last Sunday in March ... d = datetime(dt.year, 4, 1) # ends last Sunday in October ... self.dston = d - timedelta(days=d.weekday() + 1) ... d = datetime(dt.year, 11, 1) ... self.dstoff = d - timedelta(days=d.weekday() + 1) ... if self.dston <= dt.replace(tzinfo=None) < self.dstoff: ... return timedelta(hours=1) ... else: ... return timedelta(0) ... def tzname(self,dt): ... return "GMT +1" ... >>> class GMT2(tzinfo): ... def utcoffset(self, dt): ... return timedelta(hours=2) + self.dst(dt) ... def dst(self, dt): ... d = datetime(dt.year, 4, 1) ... self.dston = d - timedelta(days=d.weekday() + 1) ... d = datetime(dt.year, 11, 1) ... self.dstoff = d - timedelta(days=d.weekday() + 1) ... if self.dston <= dt.replace(tzinfo=None) < self.dstoff: ... return timedelta(hours=1) ... else: ... return timedelta(0) ... def tzname(self,dt): ... return "GMT +2" ... >>> gmt1 = GMT1() >>> # Daylight Saving Time >>> dt1 = datetime(2006, 11, 21, 16, 30, tzinfo=gmt1) >>> dt1.dst() datetime.timedelta(0) >>> dt1.utcoffset() datetime.timedelta(0, 3600) >>> dt2 = datetime(2006, 6, 14, 13, 0, tzinfo=gmt1) >>> dt2.dst() datetime.timedelta(0, 3600) >>> dt2.utcoffset() datetime.timedelta(0, 7200) >>> # Convert datetime to another time zone >>> dt3 = dt2.astimezone(GMT2()) >>> dt3 datetime.datetime(2006, 6, 14, 14, 0, tzinfo=<GMT2 object at 0x...>) >>> dt2 datetime.datetime(2006, 6, 14, 13, 0, tzinfo=<GMT1 object at 0x...>) >>> dt2.utctimetuple() == dt3.utctimetuple() True
A time object represents a (local) time of day, independent of any particular day, and subject to adjustment via a tzinfo 对象。
All arguments are optional. tzinfo 可以是 None , or an instance of a tzinfo subclass. The remaining arguments may be ints or longs, in the following ranges:
若给定自变量在那些范围之外， ValueError is raised. All default to 0 except tzinfo ，其默认为 None .
类属性：
最小可能差异介于不相等 time 对象， timedelta(microseconds=1) , although note that arithmetic on time objects is not supported.
实例属性 (只读)：
在 range(24) .
在 range(60) .
在 range(60) .
在 range(1000000) .
The object passed as the tzinfo argument to the time constructor, or None if none was passed.
支持的操作：
实例方法：
返回 time with the same value, except for those attributes given new values by whichever keyword arguments are specified. Note that tzinfo=None can be specified to create a naive time from an aware time , without conversion of the time data.
Return a string representing the time in ISO 8601 format, HH:MM:SS.mmmmmm or, if self.microsecond is 0, HH:MM:SS If utcoffset() 不返回 None , a 6-character string is appended, giving the UTC offset in (signed) hours and minutes: HH:MM:SS.mmmmmm+HH:MM or, if self.microsecond is 0, HH:MM:SS+HH:MM
For a time t , str(t) 相当于 t.isoformat() .
Return a string representing the time, controlled by an explicit format string. For a complete list of formatting directives, see section strftime() 和 strptime() 行为 .
如同 time.strftime() . This makes it possible to specify format string for a time object when using str.format() . See section strftime() 和 strptime() 行为 .
若 tzinfo is None ，返回 None , else returns self.tzinfo.utcoffset(None) , and raises an exception if the latter doesn’t return None 或 timedelta object representing a whole number of minutes with magnitude less than one day.
若 tzinfo is None ，返回 None , else returns self.tzinfo.dst(None) , and raises an exception if the latter doesn’t return None ，或 timedelta object representing a whole number of minutes with magnitude less than one day.
若 tzinfo is None ，返回 None , else returns self.tzinfo.tzname(None) , or raises an exception if the latter doesn’t return None or a string object.
范例：
>>> from datetime import time, tzinfo >>> class GMT1(tzinfo): ... def utcoffset(self, dt): ... return timedelta(hours=1) ... def dst(self, dt): ... return timedelta(0) ... def tzname(self,dt): ... return "Europe/Prague" ... >>> t = time(12, 10, 30, tzinfo=GMT1()) >>> t datetime.time(12, 10, 30, tzinfo=<GMT1 object at 0x...>) >>> gmt = GMT1() >>> t.isoformat() '12:10:30+01:00' >>> t.dst() datetime.timedelta(0) >>> t.tzname() 'Europe/Prague' >>> t.strftime("%H:%M:%S %Z") '12:10:30 Europe/Prague' >>> 'The {} is {:%H:%M}.'.format("time", t) 'The time is 12:10.'
tzinfo is an abstract base class, meaning that this class should not be instantiated directly. You need to derive a concrete subclass, and (at least) supply implementations of the standard tzinfo methods needed by the datetime methods you use. The datetime module does not supply any concrete subclasses of tzinfo .
An instance of (a concrete subclass of) tzinfo can be passed to the constructors for datetime and time objects. The latter objects view their attributes as being in local time, and the tzinfo object supports methods revealing offset of local time from UTC, the name of the time zone, and DST offset, all relative to a date or time object passed to them.
Special requirement for pickling: A tzinfo subclass must have an __init__() method that can be called with no arguments, else it can be pickled but possibly not unpickled again. This is a technical requirement that may be relaxed in the future.
A concrete subclass of tzinfo may need to implement the following methods. Exactly which methods are needed depends on the uses made of aware datetime objects. If in doubt, simply implement all of them.
Return offset of local time from UTC, in minutes east of UTC. If local time is west of UTC, this should be negative. Note that this is intended to be the total offset from UTC; for example, if a tzinfo object represents both time zone and DST adjustments, utcoffset() should return their sum. If the UTC offset isn’t known, return None . Else the value returned must be a timedelta object specifying a whole number of minutes in the range -1439 to 1439 inclusive (1440 = 24*60; the magnitude of the offset must be less than one day). Most implementations of utcoffset() will probably look like one of these two:
return CONSTANT # fixed-offset class return CONSTANT + self.dst(dt) # daylight-aware class
若 utcoffset() 不返回 None , dst() should not return None either.
默认实现的 utcoffset() 引发 NotImplementedError .
Return the daylight saving time (DST) adjustment, in minutes east of UTC, or None if DST information isn’t known. Return timedelta(0) if DST is not in effect. If DST is in effect, return the offset as a timedelta object (see utcoffset() for details). Note that DST offset, if applicable, has already been added to the UTC offset returned by utcoffset() , so there’s no need to consult dst() unless you’re interested in obtaining DST info separately. For example, datetime.timetuple() calls its tzinfo attribute’s dst() method to determine how the tm_isdst flag should be set, and tzinfo.fromutc() 调用 dst() to account for DST changes when crossing time zones.
An instance tz 的 tzinfo subclass that models both standard and daylight times must be consistent in this sense:
tz.utcoffset(dt) - tz.dst(dt)
must return the same result for every datetime dt with dt.tzinfo == tz For sane tzinfo subclasses, this expression yields the time zone’s “standard offset”, which should not depend on the date or the time, but only on geographic location. The implementation of datetime.astimezone() relies on this, but cannot detect violations; it’s the programmer’s responsibility to ensure it. If a tzinfo subclass cannot guarantee this, it may be able to override the default implementation of tzinfo.fromutc() to work correctly with astimezone() regardless.
Most implementations of dst() will probably look like one of these two:
def dst(self, dt): # a fixed-offset class: doesn't account for DST return timedelta(0)
or
def dst(self, dt): # Code to set dston and dstoff to the time zone's DST # transition times based on the input dt.year, and expressed # in standard local time. Then if dston <= dt.replace(tzinfo=None) < dstoff: return timedelta(hours=1) else: return timedelta(0)
默认实现的 dst() 引发 NotImplementedError .
Return the time zone name corresponding to the datetime 对象 dt , as a string. Nothing about string names is defined by the datetime module, and there’s no requirement that it mean anything in particular. For example, “GMT”, “UTC”, “-500”, “-5:00”, “EDT”, “US/Eastern”, “America/New York” are all valid replies. Return None if a string name isn’t known. Note that this is a method rather than a fixed string primarily because some tzinfo subclasses will wish to return different names depending on the specific value of dt passed, especially if the tzinfo class is accounting for daylight time.
默认实现的 tzname() 引发 NotImplementedError .
These methods are called by a datetime or time object, in response to their methods of the same names. A datetime object passes itself as the argument, and a time object passes None as the argument. A tzinfo subclass’s methods should therefore be prepared to accept a dt 自变量 None , or of class datetime .
当 None is passed, it’s up to the class designer to decide the best response. For example, returning None is appropriate if the class wishes to say that time objects don’t participate in the tzinfo protocols. It may be more useful for utcoffset(None) to return the standard UTC offset, as there is no other convention for discovering the standard offset.
当 datetime object is passed in response to a datetime 方法， dt.tzinfo is the same object as self . tzinfo methods can rely on this, unless user code calls tzinfo methods directly. The intent is that the tzinfo methods interpret dt as being in local time, and not need worry about objects in other timezones.
There is one more tzinfo method that a subclass may wish to override:
This is called from the default datetime.astimezone() implementation. When called from that, dt.tzinfo is self ，和 dt ‘s date and time data are to be viewed as expressing a UTC time. The purpose of fromutc() is to adjust the date and time data, returning an equivalent datetime in self ‘s local time.
Most tzinfo subclasses should be able to inherit the default fromutc() implementation without problems. It’s strong enough to handle fixed-offset time zones, and time zones accounting for both standard and daylight time, and the latter even if the DST transition times differ in different years. An example of a time zone the default fromutc() implementation may not handle correctly in all cases is one where the standard offset (from UTC) depends on the specific date and time passed, which can happen for political reasons. The default implementations of astimezone() and fromutc() may not produce the result you want if the result is one of the hours straddling the moment the standard offset changes.
Skipping code for error cases, the default fromutc() implementation acts like:
def fromutc(self, dt): # raise ValueError error if dt.tzinfo is not self dtoff = dt.utcoffset() dtdst = dt.dst() # raise ValueError if dtoff is None or dtdst is None delta = dtoff - dtdst # this is self's standard offset if delta: dt += delta # convert to standard local time dtdst = dt.dst() # raise ValueError if dtdst is None if dtdst: return dt + dtdst else: return dt
范例 tzinfo 类：
from datetime import tzinfo, timedelta, datetime ZERO = timedelta(0) HOUR = timedelta(hours=1) # A UTC class. class UTC(tzinfo): """UTC""" def utcoffset(self, dt): return ZERO def tzname(self, dt): return "UTC" def dst(self, dt): return ZERO utc = UTC() # A class building tzinfo objects for fixed-offset time zones. # Note that FixedOffset(0, "UTC") is a different way to build a # UTC tzinfo object. class FixedOffset(tzinfo): """Fixed offset in minutes east from UTC.""" def __init__(self, offset, name): self.__offset = timedelta(minutes = offset) self.__name = name def utcoffset(self, dt): return self.__offset def tzname(self, dt): return self.__name def dst(self, dt): return ZERO # A class capturing the platform's idea of local time. import time as _time STDOFFSET = timedelta(seconds = -_time.timezone) if _time.daylight: DSTOFFSET = timedelta(seconds = -_time.altzone) else: DSTOFFSET = STDOFFSET DSTDIFF = DSTOFFSET - STDOFFSET class LocalTimezone(tzinfo): def utcoffset(self, dt): if self._isdst(dt): return DSTOFFSET else: return STDOFFSET def dst(self, dt): if self._isdst(dt): return DSTDIFF else: return ZERO def tzname(self, dt): return _time.tzname[self._isdst(dt)] def _isdst(self, dt): tt = (dt.year, dt.month, dt.day, dt.hour, dt.minute, dt.second, dt.weekday(), 0, 0) stamp = _time.mktime(tt) tt = _time.localtime(stamp) return tt.tm_isdst > 0 Local = LocalTimezone() # A complete implementation of current DST rules for major US time zones. def first_sunday_on_or_after(dt): days_to_go = 6 - dt.weekday() if days_to_go: dt += timedelta(days_to_go) return dt # US DST Rules # # This is a simplified (i.e., wrong for a few cases) set of rules for US # DST start and end times. For a complete and up-to-date set of DST rules # and timezone definitions, visit the Olson Database (or try pytz): # http://www.twinsun.com/tz/tz-link.htm # http://sourceforge.net/projects/pytz/ (might not be up-to-date) # # In the US, since 2007, DST starts at 2am (standard time) on the second # Sunday in March, which is the first Sunday on or after Mar 8. DSTSTART_2007 = datetime(1, 3, 8, 2) # and ends at 2am (DST time; 1am standard time) on the first Sunday of Nov. DSTEND_2007 = datetime(1, 11, 1, 1) # From 1987 to 2006, DST used to start at 2am (standard time) on the first # Sunday in April and to end at 2am (DST time; 1am standard time) on the last # Sunday of October, which is the first Sunday on or after Oct 25. DSTSTART_1987_2006 = datetime(1, 4, 1, 2) DSTEND_1987_2006 = datetime(1, 10, 25, 1) # From 1967 to 1986, DST used to start at 2am (standard time) on the last # Sunday in April (the one on or after April 24) and to end at 2am (DST time; # 1am standard time) on the last Sunday of October, which is the first Sunday # on or after Oct 25. DSTSTART_1967_1986 = datetime(1, 4, 24, 2) DSTEND_1967_1986 = DSTEND_1987_2006 class USTimeZone(tzinfo): def __init__(self, hours, reprname, stdname, dstname): self.stdoffset = timedelta(hours=hours) self.reprname = reprname self.stdname = stdname self.dstname = dstname def __repr__(self): return self.reprname def tzname(self, dt): if self.dst(dt): return self.dstname else: return self.stdname def utcoffset(self, dt): return self.stdoffset + self.dst(dt) def dst(self, dt): if dt is None or dt.tzinfo is None: # An exception may be sensible here, in one or both cases. # It depends on how you want to treat them. The default # fromutc() implementation (called by the default astimezone() # implementation) passes a datetime with dt.tzinfo is self. return ZERO assert dt.tzinfo is self # Find start and end times for US DST. For years before 1967, return # ZERO for no DST. if 2006 < dt.year: dststart, dstend = DSTSTART_2007, DSTEND_2007 elif 1986 < dt.year < 2007: dststart, dstend = DSTSTART_1987_2006, DSTEND_1987_2006 elif 1966 < dt.year < 1987: dststart, dstend = DSTSTART_1967_1986, DSTEND_1967_1986 else: return ZERO start = first_sunday_on_or_after(dststart.replace(year=dt.year)) end = first_sunday_on_or_after(dstend.replace(year=dt.year)) # Can't compare naive to aware objects, so strip the timezone from # dt first. if start <= dt.replace(tzinfo=None) < end: return HOUR else: return ZERO Eastern = USTimeZone(-5, "Eastern", "EST", "EDT") Central = USTimeZone(-6, "Central", "CST", "CDT") Mountain = USTimeZone(-7, "Mountain", "MST", "MDT") Pacific = USTimeZone(-8, "Pacific", "PST", "PDT")
Note that there are unavoidable subtleties twice per year in a tzinfo subclass accounting for both standard and daylight time, at the DST transition points. For concreteness, consider US Eastern (UTC -0500), where EDT begins the minute after 1:59 (EST) on the second Sunday in March, and ends the minute after 1:59 (EDT) on the first Sunday in November:
UTC 3:MM 4:MM 5:MM 6:MM 7:MM 8:MM EST 22:MM 23:MM 0:MM 1:MM 2:MM 3:MM EDT 23:MM 0:MM 1:MM 2:MM 3:MM 4:MM start 22:MM 23:MM 0:MM 1:MM 3:MM 4:MM end 23:MM 0:MM 1:MM 1:MM 2:MM 3:MM
When DST starts (the “start” line), the local wall clock leaps from 1:59 to 3:00. A wall time of the form 2:MM doesn’t really make sense on that day, so astimezone(Eastern) won’t deliver a result with hour == 2 on the day DST begins. In order for astimezone() to make this guarantee, the rzinfo.dst() method must consider times in the “missing hour” (2:MM for Eastern) to be in daylight time.
When DST ends (the “end” line), there’s a potentially worse problem: there’s an hour that can’t be spelled unambiguously in local wall time: the last hour of daylight time. In Eastern, that’s times of the form 5:MM UTC on the day daylight time ends. The local wall clock leaps from 1:59 (daylight time) back to 1:00 (standard time) again. Local times of the form 1:MM are ambiguous. astimezone() mimics the local clock’s behavior by mapping two adjacent UTC hours into the same local hour then. In the Eastern example, UTC times of the form 5:MM and 6:MM both map to 1:MM when converted to Eastern. In order for astimezone() to make this guarantee, the tzinfo.dst() method must consider times in the “repeated hour” to be in standard time. This is easily arranged, as in the example, by expressing DST switch times in the time zone’s standard local time.
Applications that can’t bear such ambiguities should avoid using hybrid tzinfo subclasses; there are no ambiguities when using UTC, or any other fixed-offset tzinfo subclass (such as a class representing only EST (fixed offset -5 hours), or only EDT (fixed offset -4 hours)).
另请参阅
The standard library has no tzinfo instances, but there exists a third-party library which brings the IANA timezone database (also known as the Olson database) to Python: pytz .
pytz contains up-to-date information and its usage is recommended.
date , datetime ，和 time objects all support a strftime(format) method, to create a string representing the time under the control of an explicit format string. Broadly speaking, d.strftime(fmt) acts like the time 模块的 time.strftime(fmt, d.timetuple()) although not all objects support a timetuple() 方法。
Conversely, the datetime.strptime() class method creates a datetime object from a string representing a date and time and a corresponding format string. datetime.strptime(date_string, format) 相当于 datetime(*(time.strptime(date_string, format)[0:6])) .
For time objects, the format codes for year, month, and day should not be used, as time objects have no such values. If they’re used anyway, 1900 is substituted for the year, and 1 for the month and day.
For date objects, the format codes for hours, minutes, seconds, and microseconds should not be used, as date objects have no such values. If they’re used anyway, 0 is substituted for them.
The full set of format codes supported varies across platforms, because Python calls the platform C library’s strftime() function, and platform variations are common. To see the full set of format codes supported on your platform, consult the strftime(3) 文档编制。
The following is a list of all the format codes that the C standard (1989 version) requires, and these work on all platforms with a standard C implementation. Note that the 1999 version of the C standard added additional format codes.
The exact range of years for which strftime() works also varies across platforms. Regardless of platform, years before 1900 cannot be used.
| 指令 | 含义 | 范例 | 注意事项 |
|---|---|---|---|
| %a | Weekday as locale’s abbreviated name. |
Sun, Mon, ..., Sat
(en_US);
So, Mo, ..., Sa
(de_DE)
|
(1) |
| %A | Weekday as locale’s full name. |
Sunday, Monday, ...,
Saturday (en_US);
Sonntag, Montag, ...,
Samstag (de_DE)
|
(1) |
| %w | Weekday as a decimal number, where 0 is Sunday and 6 is Saturday. | 0, 1, ..., 6 | |
| %d | Day of the month as a zero-padded decimal number. | 01, 02, ..., 31 | |
| %b | Month as locale’s abbreviated 名称。 |
Jan, Feb, ..., Dec
(en_US);
Jan, Feb, ..., Dez
(de_DE)
|
(1) |
| %B | Month as locale’s full name. |
January, February,
..., December (en_US);
Januar, Februar, ...,
Dezember (de_DE)
|
(1) |
| %m | Month as a zero-padded decimal number. | 01, 02, ..., 12 | |
| %y | Year without century as a zero-padded decimal number. | 00, 01, ..., 99 | |
| %Y | Year with century as a decimal 编号。 | 1970, 1988, 2001, 2013 | |
| %H | Hour (24-hour clock) as a zero-padded decimal number. | 00, 01, ..., 23 | |
| %I | Hour (12-hour clock) as a zero-padded decimal number. | 01, 02, ..., 12 | |
| %p | Locale’s equivalent of either AM or PM. |
AM, PM (en_US);
am, pm (de_DE)
|
(1), (2) |
| %M | Minute as a zero-padded decimal number. | 00, 01, ..., 59 | |
| %S | Second as a zero-padded decimal number. | 00, 01, ..., 59 | (3) |
| %f | Microsecond as a decimal number, zero-padded on the left. | 000000, 000001, ..., 999999 | (4) |
| %z | UTC offset in the form +HHMM or -HHMM (empty string if the the object is naive). | (empty), +0000, -0400, +1030 | (5) |
| %Z | Time zone name (empty string if the object is naive). | (empty), UTC, EST, CST | |
| %j | Day of the year as a zero-padded decimal number. | 001, 002, ..., 366 | |
| %U | Week number of the year (Sunday as the first day of the week) as a zero padded decimal number. All days in a new year preceding the first Sunday are considered to be in week 0. | 00, 01, ..., 53 | (6) |
| %W | Week number of the year (Monday as the first day of the week) as a decimal number. All days in a new year preceding the first Monday are considered to be in week 0. | 00, 01, ..., 53 | (6) |
| %c | Locale’s appropriate date and time representation. |
Tue Aug 16 21:30:00
1988 (en_US);
Di 16 Aug 21:30:00
1988 (de_DE)
|
(1) |
| %x | Locale’s appropriate date 表示。 |
08/16/88 (None);
08/16/1988 (en_US);
16.08.1988 (de_DE)
|
(1) |
| %X | Locale’s appropriate time 表示。 |
21:30:00 (en_US);
21:30:00 (de_DE)
|
(1) |
| %% | 文字 '%' 字符。 | % |
注意事项：
Because the format depends on the current locale, care should be taken when making assumptions about the output value. Field orderings will vary (for example, “month/day/year” versus “day/month/year”), and the output may contain Unicode characters encoded using the locale’s default encoding (for example, if the current locale is ja_JP , the default encoding could be any one of eucJP , SJIS ，或 utf-8 ；使用 locale.getlocale() to determine the current locale’s encoding).
当用于 strptime() method, the %p directive only affects the output hour field if the %I directive is used to parse the hour.
不像 time module, the datetime module does not support leap seconds.
%f is an extension to the set of format characters in the C standard (but implemented separately in datetime objects, and therefore always available). When used with the strptime() method, the %f directive accepts from one to six digits and zero pads on the right.
2.6 版新增。
For a naive object, the %z and %Z format codes are replaced by empty strings.
For an aware object:
utcoffset() is transformed into a 5-character string of the form +HHMM or -HHMM, where HH is a 2-digit string giving the number of UTC offset hours, and MM is a 2-digit string giving the number of UTC offset minutes. For example, if utcoffset() 返回 timedelta(hours=-3, minutes=-30) , %z is replaced with the string '-0330' .
若 tzname() 返回 None , %Z is replaced by an empty string. Otherwise %Z is replaced by the returned value, which must be a string.
当用于 strptime() 方法， %U and %W are only used in calculations when the day of the week and the year are specified.
脚注
| [1] | If, that is, we ignore the effects of Relativity |