# Работа со временем
Для работы со временем в Python импортируют библиотеку datetime (англ. date «дата», time «время»). В ней есть не только отдельные функции, но и целый новый тип данных.
Называется он точно так же, как библиотека — datetime . Чтобы не путаться, будем подключать библиотеку под именем dt и так всегда к ней обращаться.
Тип данных datetime похож на уже привычные вам int , string и dict . Он нужен, чтобы хранить информацию о конкретном моменте времени: год, месяц, день, час, минуты, секунды и микросекунды.
Чтобы создать объект этого типа, нужно вызвать функцию datetime() из библиотеки dt . Она принимает обязательные аргументы — год, месяц и день, — и необязательные: час, минута, секунда и микросекунда, которые по умолчанию равны нулю.
Создадим объект типа datetime с датой и временем старта Гагарина:
Тип данных datetime позволяет просто вычитать даты друг из друга, как обычные числа. Вот время между стартом Гагарина и его приземлением:
# Упражнения
- Научите Виту сообщать пользователю, сколько времени шёл его любимый сериал.
- Дата выхода первой серии — 17 апреля 2011 года.
- Дата выхода последней серии — 15 апреля 2019 года.
- Напишите код, отвечающий на запрос пользователя "Сколько времени у меня уже ушло на этот курс по разработке?" Вспомните, в какой день и во сколько вы начали проходить курс. Запишите этот момент времени в переменную start_moment . В переменную current_moment запишите текущий момент времени. Затем вычислите разницу двух этих моментов, запишите её в переменную total_time , и напечатайте её на экране.
# Стандарт UTC
Есть несколько стандартов измерения и записи времени. Раньше в основном придерживались GMT (англ. «Greenwich Mean Time», среднее время по гринвичскому меридиану). Позже прежний всемирный формат был отменен и приняли новый, определяемый атомными часами. Это UTC — «coordinated universal time» — всемирное координированное время.
У каждой переменной типа данных datetime можно вызвать метод utcnow() (англ. now «сейчас»). Он вернёт текущий момент времени по UTC с эталонной точностью до микросекунд.
Более того, метод utcnow() настолько хитрый, что для его вызова необязательно явно создавать объект типа datetime . Можно просто написать:
Для получения времени другого часового пояса, есть тип timedelta (от англ. delta, «промежуток»), в котором можно сохранить определенный промежуток времени. Этот тип тоже живёт в библиотеке dt. А объект такого типа создаётся функцией timedelta() :
И прибавляем его к значению времени по UTC:
В аргументах функции timedelta() среди прочего можно указывать days (дни), hours (часы), minutes (минуты), seconds (секунды), microseconds (микросекунды).
Пример: Победитель Гран-при Австралии чемпионата мира Формулы-1 2019 года, Вале Боттас проехал свой самый быстрый круг за 1 минуту 25 секунд и 273250 микросекунд. Второй результат показал Льюис Хэмилтон с разницей в 208860 микросекунд. Вычислим время самого быстрого круга Хэмилтона.
# Упражнения
- Напишите функцию, которая по названию города скажет, сколько там сейчас времени. В словарь UTC_OFFSET (англ. offset, «сдвиг»), для каждого города записана разница местного времени и UTC в часах.
Подключите метод перебора и выведите фразу для каждого города: "В Уфе 5 часов." Используйте проверку для правильно подобранного окончания слова "часы" в зависимости от числа.
Напишите функцию, которая по имени друга скажет, сколько у него сейчас времени. В словаре DATABASE хранятся данные о том, кто из друзей где живёт.
- Подключите метод перебора друзей и выведите фразу для каждого друга: "У Димы сейчас 15 часов." Используйте проверку для правильно подобранного окончания слова "часы" в зависимости от числа.
# Форматирование времени
До сих пор вы печатали время только в одном формате.
Что делать, если хочется напечатать сообщение по-человечески, скажем: "Сейчас 10:31"? Для этого существует метод strftime() (от англ. string format time, «строковый формат времени»). Его можно применить к любому объекту типа datetime и аргументом задать формат вывода времени:
Здесь %H означает часы, %M — минуты. Кроме этих параметров, бывают ещё, например %B — месяц, %Y — год и %S — секунды, %A — название дня недели по-английски, %U — номер недели в году.
# Упражнения
- Сделайте так, чтобы функция what_time() возвращала время в формате часы:минуты .
- Примените все полученные в этой теме знания, чтобы научить Виту отвечать на вопросы про друзей, сколько у них сейчас времени:
- Артём, который час?
- Антон, который час?
Примеры таких запросов уже добавлены в список queries в функции runner() .
Working With Python datetime
Python datetime is a module to work with dates in python which has basically 4 main objects for date and time operations: date, time, datetime and timedelta. Let’s learn about this step by step where we can do all sorts of operations using these 4 objects and solve problems gradually from easy to hard.
Introduction
Whenever we need to work with dates, date time module provides the necessary tools. Since, it is python’s standard library part so we don’t need to install it separately.
You can see below how it is imported:
The most important and commonly used object is the datetime class inside the datetime module.
Please don’t get confused with the name as the module name and class name is same.
Well, besides the datetime.datetime class, we also have other 3 classes:
1 — datetime.datetime.now()
Now, very basic question anyone can ask is how do we get current date and time in python? Let’s see!
datetime.datetime.now() can give you that. Quite easy right?
We can see here, the format follows YYYY,MM,DD,HH,MM,SS,MS and gives current date time in local date and time in local timezone.
2 — datetime.date.today( )
We can also get just the dates alone using datetime.date.today( ).
Since, today( ) is a method of the datetime.date class and it doesnot contain time information.
Good, but don’t you think above notation is hard to read. If you print, it out , it will show you in a nice YYYY-MM-DD format.
3 — datetime.datetime()
We saw above how to create datetime object for current time but let us see how to create it for any date and time.
We can pass it in the same order to datetime.datetime().
4 — dateutil.parser
Now, let’s learn about parsing. Parsing is nothing but converting datetime string to a datetime format because while working with spreadsheets columns or datasets, it can come in any format.
We can import parse from dateutil.parser.
Any datestring can be converted to a datetime object using dateutil.
Similarly, we can parse a datestring to datetime.
5 — strftime
Now, formatting datetime object into any date format. We can convert any datetime object to nearly any representation of date format using strftime() method.
6 — datetime Functions
Let’s learn some useful datetime functions.
6.1 — datetime.time()
We can use the datetime.time() to represent the time component alone.
6.2 — datetime.timedelta
Let us use timedelta to get the difference between two dates or times. Syntax: datetime.timedelta
I have a timedelta object that represents a duration of 30 days. Let’s compute the date that will be 20 days from now.
We can also subtract two datetime objects, we will get a timedelta object that represent the duration.
Similarly, we can subtract two time deltas to get another timedelta object.
7 — pytz (Timezones)
Let’s complicate it a little more now.
Working with time zones.For time zones, python recommends pytz module which is not a standard built-in library. You need to install it separately (enter `pip install pytz` in terminal or command prompt) So how to set time zone to a particular datetime? Simply pass the respective pytz timezone object to tzinfo parameter when you create the datetime. Then, that datetime will become timezone aware. Let’s create a datetime object that belongs to UTC timezone.
7.1 — pytz.all_timezones
UTC was a direct attribute of the pytz module. So, how to set to a different timezone? Lookup pytz.all_timezones for your timezone of choice. Then use the pytz.timezone() to create the respective timezone object that will be passed to the tzinfo argument.
Implementation
Now let’s see example on a flight dataset. You can download dataset from here
Step 1: Import library
Step 2: Lets read the data from excel
Step 3: Check how dataset looks like
Step 4: Convert Date_of_Journey to datatime from which we will extract feature
Step 5: Extract dayofweek from datetime
Step 6: Extract day from datetime
Step 7: Extract year from datetime
Step 8: Extract month from datetime
Let’s look how our dataset looks like after extracting time feature
Congratulations! You have successfully implemented python datetime on a dataset.
time — Time access and conversions¶
This module provides various time-related functions. For related functionality, see also the datetime and calendar modules.
Although this module is always available, not all functions are available on all platforms. Most of the functions defined in this module call platform C library functions with the same name. It may sometimes be helpful to consult the platform documentation, because the semantics of these functions varies among platforms.
An explanation of some terminology and conventions is in order.
The epoch is the point where the time starts, the return value of time.gmtime(0) . It is January 1, 1970, 00:00:00 (UTC) on all platforms.
The term seconds since the epoch refers to the total number of elapsed seconds since the epoch, typically excluding leap seconds. Leap seconds are excluded from this total on all POSIX-compliant platforms.
The functions in this module may not handle dates and times before the epoch or far in the future. The cut-off point in the future is determined by the C library; for 32-bit systems, it is typically in 2038.
Function strptime() can parse 2-digit years when given %y format code. When 2-digit years are parsed, they are converted according to the POSIX and ISO C standards: values 69–99 are mapped to 1969–1999, and values 0–68 are mapped to 2000–2068.
UTC is Coordinated Universal Time (formerly known as Greenwich Mean Time, or GMT). The acronym UTC is not a mistake but a compromise between English and French.
DST is Daylight Saving Time, an adjustment of the timezone by (usually) one hour during part of the year. DST rules are magic (determined by local law) and can change from year to year. The C library has a table containing the local rules (often it is read from a system file for flexibility) and is the only source of True Wisdom in this respect.
The precision of the various real-time functions may be less than suggested by the units in which their value or argument is expressed. E.g. on most Unix systems, the clock “ticks” only 50 or 100 times a second.
On the other hand, the precision of time() and sleep() is better than their Unix equivalents: times are expressed as floating point numbers, time() returns the most accurate time available (using Unix gettimeofday() where available), and sleep() will accept a time with a nonzero fraction (Unix select() is used to implement this, where available).
The time value as returned by gmtime() , localtime() , and strptime() , and accepted by asctime() , mktime() and strftime() , is a sequence of 9 integers. The return values of gmtime() , localtime() , and strptime() also offer attribute names for individual fields.
See struct_time for a description of these objects.
Changed in version 3.3: The struct_time type was extended to provide the tm_gmtoff and tm_zone attributes when platform supports corresponding struct tm members.
Changed in version 3.6: The struct_time attributes tm_gmtoff and tm_zone are now available on all platforms.
Use the following functions to convert between time representations:
seconds since the epoch
seconds since the epoch
seconds since the epoch
seconds since the epoch
Functions¶
Convert a tuple or struct_time representing a time as returned by gmtime() or localtime() to a string of the following form: ‘Sun Jun 20 23:21:05 1993’ . The day field is two characters long and is space padded if the day is a single digit, e.g.: ‘Wed Jun 9 04:26:40 1993’ .
If t is not provided, the current time as returned by localtime() is used. Locale information is not used by asctime() .
Unlike the C function of the same name, asctime() does not add a trailing newline.
Return the clk_id of the thread-specific CPU-time clock for the specified thread_id.
Use threading.get_ident() or the ident attribute of threading.Thread objects to get a suitable value for thread_id.
Passing an invalid or expired thread_id may result in undefined behavior, such as segmentation fault.
See the man page for pthread_getcpuclockid(3) for further information.
New in version 3.7.
Return the resolution (precision) of the specified clock clk_id. Refer to Clock ID Constants for a list of accepted values for clk_id.
New in version 3.3.
Return the time of the specified clock clk_id. Refer to Clock ID Constants for a list of accepted values for clk_id.
Use clock_gettime_ns() to avoid the precision loss caused by the float type.
New in version 3.3.
Similar to clock_gettime() but return time as nanoseconds.
New in version 3.7.
Set the time of the specified clock clk_id. Currently, CLOCK_REALTIME is the only accepted value for clk_id.
Use clock_settime_ns() to avoid the precision loss caused by the float type.
New in version 3.3.
Similar to clock_settime() but set time with nanoseconds.
New in version 3.7.
Convert a time expressed in seconds since the epoch to a string of a form: ‘Sun Jun 20 23:21:05 1993’ representing local time. The day field is two characters long and is space padded if the day is a single digit, e.g.: ‘Wed Jun 9 04:26:40 1993’ .
If secs is not provided or None , the current time as returned by time() is used. ctime(secs) is equivalent to asctime(localtime(secs)) . Locale information is not used by ctime() .
time. get_clock_info ( name ) ¶
Get information on the specified clock as a namespace object. Supported clock names and the corresponding functions to read their value are:
The result has the following attributes:
adjustable: True if the clock can be changed automatically (e.g. by a NTP daemon) or manually by the system administrator, False otherwise
implementation: The name of the underlying C function used to get the clock value. Refer to Clock ID Constants for possible values.
monotonic: True if the clock cannot go backward, False otherwise
resolution: The resolution of the clock in seconds ( float )
New in version 3.3.
Convert a time expressed in seconds since the epoch to a struct_time in UTC in which the dst flag is always zero. If secs is not provided or None , the current time as returned by time() is used. Fractions of a second are ignored. See above for a description of the struct_time object. See calendar.timegm() for the inverse of this function.
time. localtime ( [ secs ] ) ¶
Like gmtime() but converts to local time. If secs is not provided or None , the current time as returned by time() is used. The dst flag is set to 1 when DST applies to the given time.
localtime() may raise OverflowError , if the timestamp is outside the range of values supported by the platform C localtime() or gmtime() functions, and OSError on localtime() or gmtime() failure. It’s common for this to be restricted to years between 1970 and 2038.
This is the inverse function of localtime() . Its argument is the struct_time or full 9-tuple (since the dst flag is needed; use -1 as the dst flag if it is unknown) which expresses the time in local time, not UTC. It returns a floating point number, for compatibility with time() . If the input value cannot be represented as a valid time, either OverflowError or ValueError will be raised (which depends on whether the invalid value is caught by Python or the underlying C libraries). The earliest date for which it can generate a time is platform-dependent.
Return the value (in fractional seconds) of a monotonic clock, i.e. a clock that cannot go backwards. The clock is not affected by system clock updates. The reference point of the returned value is undefined, so that only the difference between the results of two calls is valid.
Use monotonic_ns() to avoid the precision loss caused by the float type.
New in version 3.3.
Changed in version 3.5: The function is now always available and always system-wide.
Changed in version 3.10: On macOS, the function is now system-wide.
Similar to monotonic() , but return time as nanoseconds.
New in version 3.7.
Return the value (in fractional seconds) of a performance counter, i.e. a clock with the highest available resolution to measure a short duration. It does include time elapsed during sleep and is system-wide. The reference point of the returned value is undefined, so that only the difference between the results of two calls is valid.
Use perf_counter_ns() to avoid the precision loss caused by the float type.
New in version 3.3.
Changed in version 3.10: On Windows, the function is now system-wide.
Similar to perf_counter() , but return time as nanoseconds.
New in version 3.7.
Return the value (in fractional seconds) of the sum of the system and user CPU time of the current process. It does not include time elapsed during sleep. It is process-wide by definition. The reference point of the returned value is undefined, so that only the difference between the results of two calls is valid.
Use process_time_ns() to avoid the precision loss caused by the float type.
New in version 3.3.
Similar to process_time() but return time as nanoseconds.
New in version 3.7.
Suspend execution of the calling thread for the given number of seconds. The argument may be a floating point number to indicate a more precise sleep time.
If the sleep is interrupted by a signal and no exception is raised by the signal handler, the sleep is restarted with a recomputed timeout.
The suspension time may be longer than requested by an arbitrary amount, because of the scheduling of other activity in the system.
On Windows, if secs is zero, the thread relinquishes the remainder of its time slice to any other thread that is ready to run. If there are no other threads ready to run, the function returns immediately, and the thread continues execution. On Windows 8.1 and newer the implementation uses a high-resolution timer which provides resolution of 100 nanoseconds. If secs is zero, Sleep(0) is used.
Use clock_nanosleep() if available (resolution: 1 nanosecond);
Or use nanosleep() if available (resolution: 1 nanosecond);
Or use select() (resolution: 1 microsecond).
Changed in version 3.11: On Unix, the clock_nanosleep() and nanosleep() functions are now used if available. On Windows, a waitable timer is now used.
Changed in version 3.5: The function now sleeps at least secs even if the sleep is interrupted by a signal, except if the signal handler raises an exception (see PEP 475 for the rationale).
Convert a tuple or struct_time representing a time as returned by gmtime() or localtime() to a string as specified by the format argument. If t is not provided, the current time as returned by localtime() is used. format must be a string. ValueError is raised if any field in t is outside of the allowed range.
0 is a legal argument for any position in the time tuple; if it is normally illegal the value is forced to a correct one.
The following directives can be embedded in the format string. They are shown without the optional field width and precision specification, and are replaced by the indicated characters in the strftime() result:
datetime — Basic date and time types¶
The datetime module supplies classes for manipulating dates and times.
While date and time arithmetic is supported, the focus of the implementation is on efficient attribute extraction for output formatting and manipulation.
General calendar related functions.
Time access and conversions.
Concrete time zones representing the IANA time zone database.
Third-party library with expanded time zone and parsing support.
Aware and Naive Objects¶
Date and time objects may be categorized as “aware” or “naive” depending on whether or not they include timezone information.
With sufficient knowledge of applicable algorithmic and political time adjustments, such as time zone and daylight saving time information, an aware object can locate itself relative to other aware objects. An aware object represents 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 is 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.
Only one concrete tzinfo class, the timezone class, is supplied by the datetime module. The timezone class can represent simple timezones with fixed offsets from UTC, such as UTC itself or North American EST and EDT timezones. Supporting timezones at deeper levels of detail is up to the application. The rules for time adjustment across the world are more political than rational, change frequently, and there is no standard suitable for every application aside from UTC.
Constants¶
The datetime module exports the following constants:
The smallest year number allowed in a date or datetime object. MINYEAR is 1 .
The largest year number allowed in a date or datetime object. MAXYEAR is 9999 .
Alias for the UTC timezone singleton datetime.timezone.utc .
New in version 3.11.
Available Types¶
An idealized naive date, assuming the current Gregorian calendar always was, and always will be, in effect. Attributes: year , month , and day .
class datetime. time
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 , and tzinfo .
class datetime. datetime
A combination of a date and a time. Attributes: year , month , day , hour , minute , second , microsecond , and tzinfo .
class datetime. timedelta
A duration expressing the difference between two date , time , or datetime instances to microsecond resolution.
class datetime. tzinfo
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).
class datetime. timezone
A class that implements the tzinfo abstract base class as a fixed offset from the UTC.
New in version 3.2.
Objects of these types are immutable.
Common Properties¶
The date , datetime , time , and timezone types share these common features:
Objects of these types are immutable.
Objects of these types are hashable , meaning that they can be used as dictionary keys.
Objects of these types support efficient pickling via the pickle module.
Determining if an Object is Aware or Naive¶
Objects of the date type are always naive.
An object of type time or datetime may be aware or naive.
A datetime object d is aware if both of the following hold:
d.tzinfo is not None
d.tzinfo.utcoffset(d) does not return None
Otherwise, d is naive.
A time object t is aware if both of the following hold:
t.tzinfo is not None
t.tzinfo.utcoffset(None) does not return None .
Otherwise, t is naive.
The distinction between aware and naive doesn’t apply to timedelta objects.
timedelta Objects¶
A timedelta object represents a duration, the difference between two dates or times.
class datetime. timedelta ( days = 0 , seconds = 0 , microseconds = 0 , milliseconds = 0 , minutes = 0 , hours = 0 , weeks = 0 ) ¶
All arguments are optional and default to 0 . Arguments may be integers or floats, and may be positive or negative.
Only days, seconds and microseconds are stored internally. Arguments are converted to those units:
A millisecond is converted to 1000 microseconds.
A minute is converted to 60 seconds.
An hour is converted to 3600 seconds.
A week is converted to 7 days.
and days, seconds and microseconds are then normalized so that the representation is unique, with
0 <= microseconds < 1000000
0 <= seconds < 3600*24 (the number of seconds in one day)
-999999999 <= days <= 999999999
The following example illustrates how any arguments besides days, seconds and microseconds are “merged” and normalized into those three resulting attributes:
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 using round-half-to-even tiebreaker. 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 is raised.
Note that normalization of negative values may be surprising at first. For example:
The most negative timedelta object, timedelta(-999999999) .
The most positive timedelta object, timedelta(days=999999999, hours=23, minutes=59, seconds=59, microseconds=999999) .
The smallest possible difference between non-equal timedelta objects, timedelta(microseconds=1) .
Note that, because of normalization, timedelta.max > -timedelta.min . -timedelta.max is not representable as a timedelta object.
Instance attributes (read-only):
Between -999999999 and 999999999 inclusive
Between 0 and 86399 inclusive
Between 0 and 999999 inclusive
Difference of t2 and t3. Afterwards t1 == t2 — t3 and t2 == t1 + t3 are true. (1)(6)
t1 = t2 * i or t1 = i * t2
Delta multiplied by an integer. Afterwards t1 // i == t2 is true, provided i != 0 .
In general, t1 * i == t1 * (i-1) + t1 is true. (1)
t1 = t2 * f or t1 = f * t2
Delta multiplied by a float. The result is rounded to the nearest multiple of timedelta.resolution using round-half-to-even.
Division (3) of overall duration t2 by interval unit t3. Returns a float object.
t1 = t2 / f or t1 = t2 / i
Delta divided by a float or an int. The result is rounded to the nearest multiple of timedelta.resolution using round-half-to-even.
t1 = t2 // i or t1 = t2 // t3
The floor is computed and the remainder (if any) is thrown away. In the second case, an integer is returned. (3)
The remainder is computed as a timedelta object. (3)
q, r = divmod(t1, t2)
Computes the quotient and the remainder: q = t1 // t2 (3) and r = t1 % t2 . q is an integer and r is a timedelta object.
Returns a timedelta object with the same value. (2)
equivalent to timedelta (-t1.days, —t1.seconds, —t1.microseconds), and to t1* -1. (1)(4)
equivalent to +t when t.days >= 0 , and to —t when t.days < 0 . (2)
Returns a string in the form [D day[s], ][H]H:MM:SS[.UUUUUU] , where D is negative for negative t . (5)
Returns a string representation of the timedelta object as a constructor call with canonical attribute values.
This is exact but may overflow.
This is exact and cannot overflow.
—timedelta.max is not representable as a timedelta object.
String representations of timedelta objects are normalized similarly to their internal representation. This leads to somewhat unusual results for negative timedeltas. For example:
The expression t2 — t3 will always be equal to the expression t2 + (-t3) except when t3 is equal to timedelta.max ; in that case the former will produce a result while the latter will overflow.
In addition to the operations listed above, timedelta objects support certain additions and subtractions with date and datetime objects (see below).
Changed in version 3.2: Floor division and true division of a timedelta object by another timedelta object are now supported, as are remainder operations and the divmod() function. True division and multiplication of a timedelta object by a float object are now supported.
Comparisons of timedelta objects are supported, with some caveats.
The comparisons == or != always return a bool , no matter the type of the compared object:
For all other comparisons (such as < and > ), when a timedelta object is compared to an object of a different type, TypeError is raised:
In Boolean contexts, a timedelta object is considered to be true if and only if it isn’t equal to timedelta(0) .
Return the total number of seconds contained in the duration. Equivalent to td / timedelta(seconds=1) . For interval units other than seconds, use the division form directly (e.g. td / timedelta(microseconds=1) ).
Note that for very large time intervals (greater than 270 years on most platforms) this method will lose microsecond accuracy.
New in version 3.2.
Examples of usage: timedelta ¶
An additional example of normalization:
Examples of timedelta arithmetic:
date Objects¶
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. 2
All arguments are required. Arguments must be integers, in the following ranges:
MINYEAR <= year <= MAXYEAR
1 <= day <= number of days in the given month and year
If an argument outside those ranges is given, ValueError is raised.
Other constructors, all class methods:
classmethod date. today ( ) ¶
Return the current local date.
This is equivalent to date.fromtimestamp(time.time()) .
classmethod date. fromtimestamp ( timestamp ) ¶
Return the local date corresponding to the POSIX timestamp, such as is returned by time.time() .
This may raise OverflowError , if the timestamp is out of the range of values supported by the platform C localtime() function, and OSError on localtime() failure. 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() .
Changed in version 3.3: Raise OverflowError instead of ValueError if the timestamp is out of the range of values supported by the platform C localtime() function. Raise OSError instead of ValueError on localtime() failure.
Return the date corresponding to the proleptic Gregorian ordinal, where January 1 of year 1 has ordinal 1.
ValueError is raised unless 1 <= ordinal <= date.max.toordinal() . For any date d, date.fromordinal(d.toordinal()) == d .
classmethod date. fromisoformat ( date_string ) ¶
Return a date corresponding to a date_string given in any valid ISO 8601 format, except ordinal dates (e.g. YYYY-DDD ):
New in version 3.7.
Changed in version 3.11: Previously, this method only supported the format YYYY-MM-DD .
Return a date corresponding to the ISO calendar date specified by year, week and day. This is the inverse of the function date.isocalendar() .
New in version 3.8.
The earliest representable date, date(MINYEAR, 1, 1) .
The latest representable date, date(MAXYEAR, 12, 31) .
The smallest possible difference between non-equal date objects, timedelta(days=1) .
Instance attributes (read-only):
Between MINYEAR and MAXYEAR inclusive.
Between 1 and 12 inclusive.
Between 1 and the number of days in the given month of the given year.
date2 = date1 + timedelta
date2 will be timedelta.days days after date1. (1)
date2 = date1 — timedelta
Computes date2 such that date2 + timedelta == date1 . (2)
timedelta = date1 — date2
date1 is considered less than date2 when date1 precedes date2 in time. (4)
date2 is moved forward in time if timedelta.days > 0 , or backward if timedelta.days < 0 . Afterward date2 — date1 == timedelta.days . timedelta.seconds and timedelta.microseconds are ignored. OverflowError is raised if date2.year would be smaller than MINYEAR or larger than MAXYEAR .
timedelta.seconds and timedelta.microseconds are ignored.
This is exact, and cannot overflow. timedelta.seconds and timedelta.microseconds are 0, and date2 + timedelta == date1 after.
In other words, date1 < date2 if and only if date1.toordinal() < date2.toordinal() . Date comparison raises TypeError if the other comparand isn’t also a date 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 date 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 , respectively.
In Boolean contexts, all date objects are considered to be true.
date. replace ( year = self.year , month = self.month , day = self.day ) ¶
Return a date with the same value, except for those parameters given new values by whichever keyword arguments are specified.
The hours, minutes and seconds are 0, and the DST flag is -1.
d.timetuple() is equivalent to:
where 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 object 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 named tuple object with three components: year , week and weekday .
The ISO calendar is a widely used variant of the Gregorian calendar. 3
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:
Changed in version 3.9: Result changed from a tuple to a named tuple .
Return a string representing the date in ISO 8601 format, YYYY-MM-DD :
For a date d, str(d) is equivalent to d.isoformat() .
Return a string representing the date:
d.ctime() is equivalent to:
on platforms where the native C ctime() function (which time.ctime() invokes, but which date.ctime() does not invoke) conforms to the C standard.
date. strftime ( format ) ¶
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 strftime() and strptime() Behavior .
date. __format__ ( format ) ¶
Same as date.strftime() . This makes it possible to specify a format string for a date object in formatted string literals and when using str.format() . For a complete list of formatting directives, see strftime() and strptime() Behavior .
Examples of Usage: date ¶
Example of counting days to an event:
More examples of working with date :
datetime Objects¶
A datetime object is a single object containing all the information from a date object and a time object.
Like a date object, 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.
class datetime. datetime ( year , month , day , hour = 0 , minute = 0 , second = 0 , microsecond = 0 , tzinfo = None , * , fold = 0 ) ¶
The year, month and day arguments are required. tzinfo may be None , or an instance of a tzinfo subclass. The remaining arguments must be integers in the following ranges:
MINYEAR <= year <= MAXYEAR ,
1 <= day <= number of days in the given month and year ,
0 <= microsecond < 1000000 ,
If an argument outside those ranges is given, ValueError is raised.
New in version 3.6: Added the fold argument.
Other constructors, all class methods:
classmethod datetime. today ( ) ¶
Return the current local datetime, with tzinfo None .
This method is functionally equivalent to now() , but without a tz parameter.
classmethod datetime. now ( tz = None ) ¶
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() function).
If tz is not None , it must be an instance of a tzinfo subclass, and the current date and time are converted to tz’s time zone.
This function is preferred over today() and utcnow() .
classmethod datetime. 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. An aware current UTC datetime can be obtained by calling datetime.now(timezone.utc) . See also now() .
Because naive datetime objects are treated by many datetime methods as local times, it is preferred to use aware datetimes to represent times in UTC. As such, the recommended way to create an object representing the current time in UTC is by calling datetime.now(timezone.utc) .
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.
If tz is not None , it must be an instance of a tzinfo subclass, and the timestamp is converted to tz’s time zone.
fromtimestamp() may raise OverflowError , if the timestamp is out of the range of values supported by the platform C localtime() or gmtime() functions, and OSError on localtime() or gmtime() failure. 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. This method is preferred over utcfromtimestamp() .
Changed in version 3.3: Raise OverflowError instead of ValueError if the timestamp is out of the range of values supported by the platform C localtime() or gmtime() functions. Raise OSError instead of ValueError on localtime() or gmtime() failure.
Changed in version 3.6: fromtimestamp() may return instances with fold set to 1.
Return the UTC datetime corresponding to the POSIX timestamp, with tzinfo None . (The resulting object is naive.)
This may raise OverflowError , if the timestamp is out of the range of values supported by the platform C gmtime() function, and OSError on gmtime() failure. It’s common for this to be restricted to years in 1970 through 2038.
To get an aware datetime object, call fromtimestamp() :
On the POSIX compliant platforms, it is equivalent to the following expression:
except the latter formula always supports the full years range: between MINYEAR and MAXYEAR inclusive.
Because naive datetime objects are treated by many datetime methods as local times, it is preferred to use aware datetimes to represent times in UTC. As such, the recommended way to create an object representing a specific timestamp in UTC is by calling datetime.fromtimestamp(timestamp, tz=timezone.utc) .
Changed in version 3.3: Raise OverflowError instead of ValueError if the timestamp is out of the range of values supported by the platform C gmtime() function. Raise OSError instead of ValueError on gmtime() failure.
Return the datetime corresponding to the proleptic Gregorian ordinal, where January 1 of year 1 has ordinal 1. ValueError is raised unless 1 <= ordinal <= datetime.max.toordinal() . The hour, minute, second and microsecond of the result are all 0, and tzinfo is None .
classmethod datetime. combine ( date , time , tzinfo = self.tzinfo ) ¶
Return a new datetime object whose date components are equal to the given date object’s, and whose time components are equal to the given time object’s. If the tzinfo argument is provided, its value is used to set the tzinfo attribute of the result, otherwise the tzinfo attribute of the time argument is used.
For any datetime object d, d == datetime.combine(d.date(), d.time(), d.tzinfo) . If date is a datetime object, its time components and tzinfo attributes are ignored.
Changed in version 3.6: Added the tzinfo argument.
Return a datetime corresponding to a date_string in any valid ISO 8601 format, with the following exceptions:
Time zone offsets may have fractional seconds.
The T separator may be replaced by any single unicode character.
Ordinal dates are not currently supported.
Fractional hours and minutes are not supported.
New in version 3.7.
Changed in version 3.11: Previously, this method only supported formats that could be emitted by date.isoformat() or datetime.isoformat() .
Return a datetime corresponding to the ISO calendar date specified by year, week and day. The non-date components of the datetime are populated with their normal default values. This is the inverse of the function datetime.isocalendar() .
New in version 3.8.
Return a datetime corresponding to date_string, parsed according to format.
This is equivalent to:
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 strftime() and strptime() Behavior .
The earliest representable datetime , datetime(MINYEAR, 1, 1, tzinfo=None) .
The latest representable datetime , datetime(MAXYEAR, 12, 31, 23, 59, 59, 999999, tzinfo=None) .
The smallest possible difference between non-equal datetime objects, timedelta(microseconds=1) .
Instance attributes (read-only):
Between MINYEAR and MAXYEAR inclusive.
Between 1 and 12 inclusive.
Between 1 and the number of days in the given month of the given year.
The object passed as the tzinfo argument to the datetime constructor, or None if none was passed.
In [0, 1] . Used to disambiguate wall times during a repeated interval. (A repeated interval occurs when clocks are rolled back at the end of daylight saving time or when the UTC offset for the current zone is decreased for political reasons.) The value 0 (1) represents the earlier (later) of the two moments with the same wall time representation.
New in version 3.6.
datetime2 = datetime1 + timedelta
datetime2 = datetime1 — timedelta
timedelta = datetime1 — datetime2
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 or larger than 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.
Subtraction of a datetime from a datetime is defined only if both operands are naive, or if both are aware. If one is aware and the other is naive, TypeError is raised.
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 object t such that 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 is considered less than datetime2 when datetime1 precedes datetime2 in time.
If one comparand is naive and the other is aware, TypeError is raised if an order comparison is attempted. For equality comparisons, naive instances are never equal to aware instances.
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() ).
Changed in version 3.3: Equality comparisons between aware and naive datetime instances don’t raise TypeError .
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 , respectively.
Return date object with same year, month and day.
Return time object with same hour, minute, second, microsecond and fold. tzinfo is None . See also method timetz() .
Changed in version 3.6: The fold value is copied to the returned time object.
Return time object with same hour, minute, second, microsecond, fold, and tzinfo attributes. See also method time() .
Changed in version 3.6: The fold value is copied to the returned time object.
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.
New in version 3.6: Added the fold argument.
Return a datetime object with new tzinfo attribute tz, adjusting the date and time data so the result is the same UTC time as self, but in tz’s local time.
If provided, tz must be an instance of a tzinfo subclass, and its utcoffset() and dst() methods must not return None . If self is naive, it is presumed to represent time in the system timezone.
If called without arguments (or with tz=None ) the system local timezone is assumed for the target timezone. The .tzinfo attribute of the converted datetime instance will be set to an instance of timezone with the zone name and offset obtained from the OS.
If self.tzinfo is tz, self.astimezone(tz) is equal to self: no adjustment of date or time data is performed. Else the result is local time in the timezone tz, representing the same UTC time as self: after astz = dt.astimezone(tz) , astz — astz.utcoffset() will have the same date and time data as dt — dt.utcoffset() .
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:
Changed in version 3.3: tz now can be omitted.
Changed in version 3.6: The astimezone() method can now be called on naive instances that are presumed to represent system local time.
If tzinfo is None , returns None , else returns self.tzinfo.utcoffset(self) , and raises an exception if the latter doesn’t return None or a timedelta object with magnitude less than one day.
Changed in version 3.7: The UTC offset is not restricted to a whole number of minutes.
If tzinfo is None , returns None , else returns self.tzinfo.dst(self) , and raises an exception if the latter doesn’t return None or a timedelta object with magnitude less than one day.
Changed in version 3.7: The DST offset is not restricted to a whole number of minutes.
If tzinfo is None , returns None , else returns self.tzinfo.tzname(self) , raises an exception if the latter doesn’t return None or a string object,
d.timetuple() is equivalent to:
where 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() method: tzinfo is None or dst() returns None , tm_isdst is set to -1 ; else if dst() returns a non-zero value, tm_isdst is set to 1 ; else tm_isdst is set to 0 .
If datetime instance d is naive, this is the same as d.timetuple() except that tm_isdst is forced to 0 regardless of what d.dst() returns. DST is never in effect for a UTC time.
If d is aware, d is normalized to UTC time, by subtracting d.utcoffset() , and a time.struct_time for the normalized time is returned. tm_isdst is forced to 0. Note that an OverflowError may be raised if d.year was MINYEAR or MAXYEAR and UTC adjustment spills over a year boundary.
Because naive datetime objects are treated by many datetime methods as local times, it is preferred to use aware datetimes to represent times in UTC; as a result, using datetime.utctimetuple() may give misleading results. If you have a naive datetime representing UTC, use datetime.replace(tzinfo=timezone.utc) to make it aware, at which point you can use datetime.timetuple() .
Return the proleptic Gregorian ordinal of the date. The same as self.date().toordinal() .
Return POSIX timestamp corresponding to the datetime instance. The return value is a float similar to that returned by time.time() .
Naive datetime instances are assumed to represent local time and this method relies on the platform C mktime() function to perform the conversion. Since datetime supports wider range of values than mktime() on many platforms, this method may raise OverflowError for times far in the past or far in the future.
For aware datetime instances, the return value is computed as:
New in version 3.3.
Changed in version 3.6: The timestamp() method uses the fold attribute to disambiguate the times during a repeated interval.
There is no method to obtain the POSIX timestamp directly from a naive datetime instance representing UTC time. If your application uses this convention and your system timezone is not set to UTC, you can obtain the POSIX timestamp by supplying tzinfo=timezone.utc :
or by calculating the timestamp directly:
Return the day of the week as an integer, where Monday is 0 and Sunday is 6. The same as self.date().weekday() . See also isoweekday() .
Return the day of the week as an integer, where Monday is 1 and Sunday is 7. The same as self.date().isoweekday() . See also weekday() , isocalendar() .
Return a named tuple with three components: year , week and weekday . The same as self.date().isocalendar() .
datetime. isoformat ( sep = ‘T’ , timespec = ‘auto’ ) ¶
Return a string representing the date and time in ISO 8601 format:
YYYY-MM-DDTHH:MM:SS.ffffff , if microsecond is not 0
YYYY-MM-DDTHH:MM:SS , if microsecond is 0
If utcoffset() does not return None , a string is appended, giving the UTC offset:
YYYY-MM-DDTHH:MM:SS.ffffff+HH:MM[:SS[.ffffff]] , if microsecond is not 0
YYYY-MM-DDTHH:MM:SS+HH:MM[:SS[.ffffff]] , if microsecond is 0
The optional argument sep (default ‘T’ ) is a one-character separator, placed between the date and time portions of the result. For example:
The optional argument timespec specifies the number of additional components of the time to include (the default is ‘auto’ ). It can be one of the following:
‘auto’ : Same as ‘seconds’ if microsecond is 0, same as ‘microseconds’ otherwise.
‘hours’ : Include the hour in the two-digit HH format.
‘minutes’ : Include hour and minute in HH:MM format.
‘seconds’ : Include hour , minute , and second in HH:MM:SS format.
‘milliseconds’ : Include full time, but truncate fractional second part to milliseconds. HH:MM:SS.sss format.
‘microseconds’ : Include full time in HH:MM:SS.ffffff format.
Excluded time components are truncated, not rounded.
ValueError will be raised on an invalid timespec argument:
New in version 3.6: Added the timespec argument.
For a datetime instance d, str(d) is equivalent to d.isoformat(‘ ‘) .
Return a string representing the date and time:
The output string will not include time zone information, regardless of whether the input is aware or naive.
d.ctime() is equivalent to:
on platforms where the native C ctime() function (which time.ctime() invokes, but which datetime.ctime() does not invoke) conforms to the C standard.
datetime. strftime ( format ) ¶
Return a string representing the date and time, controlled by an explicit format string. For a complete list of formatting directives, see strftime() and strptime() Behavior .
datetime. __format__ ( format ) ¶
Same as datetime.strftime() . This makes it possible to specify a format string for a datetime object in formatted string literals and when using str.format() . For a complete list of formatting directives, see strftime() and strptime() Behavior .
Examples of Usage: datetime ¶
Examples of working with datetime objects:
The example below defines a tzinfo subclass capturing time zone information for Kabul, Afghanistan, which used +4 UTC until 1945 and then +4:30 UTC thereafter:
Usage of KabulTz from above:
time Objects¶
A time object represents a (local) time of day, independent of any particular day, and subject to adjustment via a tzinfo object.
class datetime. time ( hour = 0 , minute = 0 , second = 0 , microsecond = 0 , tzinfo = None , * , fold = 0 ) ¶
All arguments are optional. tzinfo may be None , or an instance of a tzinfo subclass. The remaining arguments must be integers in the following ranges:
0 <= microsecond < 1000000 ,
If an argument outside those ranges is given, ValueError is raised. All default to 0 except tzinfo, which defaults to None .
The earliest representable time , time(0, 0, 0, 0) .
The latest representable time , time(23, 59, 59, 999999) .
The smallest possible difference between non-equal time objects, timedelta(microseconds=1) , although note that arithmetic on time objects is not supported.
Instance attributes (read-only):
The object passed as the tzinfo argument to the time constructor, or None if none was passed.
In [0, 1] . Used to disambiguate wall times during a repeated interval. (A repeated interval occurs when clocks are rolled back at the end of daylight saving time or when the UTC offset for the current zone is decreased for political reasons.) The value 0 (1) represents the earlier (later) of the two moments with the same wall time representation.
New in version 3.6.
time objects support comparison of time to time , where a is considered less than b when a precedes b in time. If one comparand is naive and the other is aware, TypeError is raised if an order comparison is attempted. For equality comparisons, naive instances are never equal to aware instances.
If both comparands are aware, and have the same tzinfo attribute, the common tzinfo attribute is ignored and the base times 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() ). In order to stop mixed-type comparisons from falling back to the default comparison by object address, when a time 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 , respectively.
Changed in version 3.3: Equality comparisons between aware and naive time instances don’t raise TypeError .
In Boolean contexts, a time object is always considered to be true.
Changed in version 3.5: Before Python 3.5, a time object was considered to be false if it represented midnight in UTC. This behavior was considered obscure and error-prone and has been removed in Python 3.5. See bpo-13936 for full details.
classmethod time. fromisoformat ( time_string ) ¶
Return a time corresponding to a time_string in any valid ISO 8601 format, with the following exceptions:
Time zone offsets may have fractional seconds.
The leading T , normally required in cases where there may be ambiguity between a date and a time, is not required.
Fractional seconds may have any number of digits (anything beyond 6 will be truncated).
Fractional hours and minutes are not supported.
New in version 3.7.
Changed in version 3.11: Previously, this method only supported formats that could be emitted by time.isoformat() .
time. replace ( hour = self.hour , minute = self.minute , second = self.second , microsecond = self.microsecond , tzinfo = self.tzinfo , * , fold = 0 ) ¶
Return a 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.
New in version 3.6: Added the fold argument.
Return a string representing the time in ISO 8601 format, one of:
HH:MM:SS.ffffff , if microsecond is not 0
HH:MM:SS , if microsecond is 0
HH:MM:SS.ffffff+HH:MM[:SS[.ffffff]] , if utcoffset() does not return None
HH:MM:SS+HH:MM[:SS[.ffffff]] , if microsecond is 0 and utcoffset() does not return None
The optional argument timespec specifies the number of additional components of the time to include (the default is ‘auto’ ). It can be one of the following:
‘auto’ : Same as ‘seconds’ if microsecond is 0, same as ‘microseconds’ otherwise.
‘hours’ : Include the hour in the two-digit HH format.
‘minutes’ : Include hour and minute in HH:MM format.
‘seconds’ : Include hour , minute , and second in HH:MM:SS format.
‘milliseconds’ : Include full time, but truncate fractional second part to milliseconds. HH:MM:SS.sss format.
‘microseconds’ : Include full time in HH:MM:SS.ffffff format.
Excluded time components are truncated, not rounded.
ValueError will be raised on an invalid timespec argument.
New in version 3.6: Added the timespec argument.
For a time t, str(t) is equivalent to t.isoformat() .
time. strftime ( format ) ¶
Return a string representing the time, controlled by an explicit format string. For a complete list of formatting directives, see strftime() and strptime() Behavior .
time. __format__ ( format ) ¶
Same as time.strftime() . This makes it possible to specify a format string for a time object in formatted string literals and when using str.format() . For a complete list of formatting directives, see strftime() and strptime() Behavior .
If tzinfo is None , returns None , else returns self.tzinfo.utcoffset(None) , and raises an exception if the latter doesn’t return None or a timedelta object with magnitude less than one day.
Changed in version 3.7: The UTC offset is not restricted to a whole number of minutes.
If tzinfo is None , returns None , else returns self.tzinfo.dst(None) , and raises an exception if the latter doesn’t return None , or a timedelta object with magnitude less than one day.
Changed in version 3.7: The DST offset is not restricted to a whole number of minutes.
If tzinfo is None , returns None , else returns self.tzinfo.tzname(None) , or raises an exception if the latter doesn’t return None or a string object.
Examples of Usage: time ¶
Examples of working with a time object:
tzinfo Objects¶
This is an abstract base class, meaning that this class should not be instantiated directly. Define a subclass of tzinfo to capture information about a particular time zone.
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.
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 provides timezone , a simple concrete subclass of tzinfo which can represent timezones with fixed offset from UTC such as UTC itself or North American EST and EDT.
Special requirement for pickling: A tzinfo subclass must have an __init__() method that can be called with no arguments, otherwise 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.
tzinfo. utcoffset ( dt ) ¶
Return offset of local time from UTC, as a timedelta object that is positive east of UTC. If local time is west of UTC, this should be negative.
This represents 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 strictly between -timedelta(hours=24) and timedelta(hours=24) (the magnitude of the offset must be less than one day). Most implementations of utcoffset() will probably look like one of these two:
If utcoffset() does not return None , dst() should not return None either.
The default implementation of utcoffset() raises NotImplementedError .
Changed in version 3.7: The UTC offset is not restricted to a whole number of minutes.
Return the daylight saving time (DST) adjustment, as a timedelta object 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() calls dst() to account for DST changes when crossing time zones.
An instance tz of a tzinfo subclass that models both standard and daylight times must be consistent in this sense:
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:
The default implementation of dst() raises NotImplementedError .
Changed in version 3.7: The DST offset is not restricted to a whole number of minutes.
Return the time zone name corresponding to the datetime object 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.
The default implementation of tzname() raises 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 argument of None , or of class datetime .
When 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.
When a datetime object is passed in response to a datetime method, 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:
tzinfo. fromutc ( dt ) ¶
This is called from the default datetime.astimezone() implementation. When called from that, dt.tzinfo is self, and 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:
In the following tzinfo_examples.py file there are some examples of tzinfo classes:
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:
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. For example, at the Spring forward transition of 2016, we get:
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, but earlier times have the fold attribute set to 0 and the later times have it set to 1. For example, at the Fall back transition of 2016, we get:
Note that the datetime instances that differ only by the value of the fold attribute are considered equal in comparisons.
Applications that can’t bear wall-time ambiguities should explicitly check the value of the fold attribute or avoid using hybrid tzinfo subclasses; there are no ambiguities when using timezone , 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)).
zoneinfo
The datetime module has a basic timezone class (for handling arbitrary fixed offsets from UTC) and its timezone.utc attribute (a UTC timezone instance).
zoneinfo brings the IANA timezone database (also known as the Olson database) to Python, and its usage is recommended.
The Time Zone Database (often called tz, tzdata or zoneinfo) contains code and data that represent the history of local time for many representative locations around the globe. It is updated periodically to reflect changes made by political bodies to time zone boundaries, UTC offsets, and daylight-saving rules.
timezone Objects¶
The timezone class is a subclass of tzinfo , each instance of which represents a timezone defined by a fixed offset from UTC.
Objects of this class cannot be used to represent timezone information in the locations where different offsets are used in different days of the year or where historical changes have been made to civil time.
class datetime. timezone ( offset , name = None ) ¶
The offset argument must be specified as a timedelta object representing the difference between the local time and UTC. It must be strictly between -timedelta(hours=24) and timedelta(hours=24) , otherwise ValueError is raised.
The name argument is optional. If specified it must be a string that will be used as the value returned by the datetime.tzname() method.
New in version 3.2.
Changed in version 3.7: The UTC offset is not restricted to a whole number of minutes.
Return the fixed value specified when the timezone instance is constructed.
The dt argument is ignored. The return value is a timedelta instance equal to the difference between the local time and UTC.
Changed in version 3.7: The UTC offset is not restricted to a whole number of minutes.
Return the fixed value specified when the timezone instance is constructed.
If name is not provided in the constructor, the name returned by tzname(dt) is generated from the value of the offset as follows. If offset is timedelta(0) , the name is “UTC”, otherwise it is a string in the format UTC±HH:MM , where ± is the sign of offset , HH and MM are two digits of offset.hours and offset.minutes respectively.
Changed in version 3.6: Name generated from offset=timedelta(0) is now plain ‘UTC’ , not ‘UTC+00:00’ .
Always returns None .
timezone. fromutc ( dt ) ¶
Return dt + offset . The dt argument must be an aware datetime instance, with tzinfo set to self .
The UTC timezone, timezone(timedelta(0)) .
strftime() and strptime() Behavior¶
date , datetime , and time objects all support a strftime(format) method, to create a string representing the time under the control of an explicit format string.
Conversely, the datetime.strptime() class method creates a datetime object from a string representing a date and time and a corresponding format string.
The table below provides a high-level comparison of strftime() versus strptime() :