"datetime" --- Basic date and time types#

Código fuente: Lib/datetime.py

======================================================================

The "datetime" module supplies classes for manipulating dates and times.

Si bien la implementación permite operaciones aritméticas con fechas y horas, su principal objetivo es poder extraer campos de forma eficiente para su posterior manipulación o formateo.

Truco:

Skip to the format codes.

Ver también:

Módulo "calendar" Funciones generales relacionadas a calendar.

Módulo "time" Acceso a tiempo y conversiones.

Módulo "zoneinfo" Zonas horarias concretas que representan la base de datos de zonas horarias de la IANA.

Paquete dateutil Biblioteca de terceros con zona horaria ampliada y soporte de análisis.

Package DateType Third-party library that introduces distinct static types to for example, allow static type checkers to differentiate between naive and aware datetimes.

Aware and naive objects#

Date and time objects may be categorized as "aware" or "naive" depending on whether or not they include time zone information.

Con suficiente conocimiento de los ajustes de tiempo políticos y algorítmicos aplicables, como la zona horaria y la información del horario de verano, un objeto consciente puede ubicarse en relación con otros objetos conscientes. Un objeto consciente representa un momento específico en el tiempo que no está abierto a interpretación. [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 time zone 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 time zones with fixed offsets from UTC, such as UTC itself or North American EST and EDT time zones. Supporting time zones 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.

Constantes#

The "datetime" module exports the following constants:

datetime.MINYEAR

The smallest year number allowed in a "date" or "datetime" object. "MINYEAR" is 1.

datetime.MAXYEAR

The largest year number allowed in a "date" or "datetime" object. "MAXYEAR" is 9999.

datetime.UTC

Alias for the UTC time zone singleton "datetime.timezone.utc".

Added in version 3.11.

Available types#

class datetime.date

Una fecha naíf (naive) idealizada, suponiendo que el calendario gregoriano actual siempre estuvo, y siempre estará, vigente. Atributos: "year", "month", y "day".

class datetime.time

Un tiempo idealizado, independiente de cualquier día en particular, suponiendo que cada día tenga exactamente 24 60 60 segundos. (Aquí no hay noción de "segundos intercalares".) Atributos: "hour", "minute", "second", "microsecond", y "tzinfo".

class datetime.datetime

Una combinación de una fecha y una hora. Atributos: "year", "month", "day", "hour", "minute", "second", "microsecond" , y "tzinfo".

class datetime.timedelta

A duration expressing the difference between two "datetime" or "date" instances to microsecond resolution.

class datetime.tzinfo

Una clase base abstracta para objetos de información de zona horaria. Estos son utilizados por las clases "datetime" y "time" para proporcionar una noción personalizable de ajuste de hora (por ejemplo, para tener en cuenta la zona horaria y / o el horario de verano).

class datetime.timezone

Una clase que implementa la clase de base abstracta "tzinfo" como un desplazamiento fijo desde el UTC.

Added in version 3.2.

Los objetos de este tipo son inmutables.

Subclass relationships:

[imagen: timedelta, tzinfo, time, and date inherit from object; timezone inherits from tzinfo; and datetime inherits from date.][imagen]

Common properties#

Las clases "date", "datetime", "time", y "timezone" comparten estas características comunes:

• Los objetos de este tipo son inmutables.

• Objects of these types are hashable, meaning that they can be used as dictionary keys.

• Los objetos de este tipo admiten el pickling eficiente a través del módulo "pickle".

Determining if an object is aware or naive#

Los objetos del tipo "date" son siempre naíf (naive).

Un objeto de tipo "time" o "datetime" puede ser consciente (aware) o naíf (naive).

A "datetime" object "d" is aware if both of the following hold:

1. "d.tzinfo" no es "None"

2. "d.tzinfo.utcoffset(d)" no retorna "None"

Otherwise, "d" is naive.

A "time" object "t" is aware if both of the following hold:

1. "t.tzinfo" no es "None"

2. "t.tzinfo.utcoffset(None)" no retorna "None".

Otherwise, "t" is naive.

La distinción entre los objetos consciente (aware) y naíf (naive) no se aplica a "timedelta".

"timedelta" objects#

A "timedelta" object represents a duration, the difference between two "datetime" or "date" instances.

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.

Solo days, seconds y microseconds se almacenan internamente. Los argumentos se convierten a esas unidades:

• Un milisegundo se convierte a 1000 microsegundos.

• Un minuto se convierte a 60 segundos.

• Una hora se convierte a 3600 segundos.

• Una semana se convierte a 7 días.

y los días, segundos y microsegundos se normalizan para que la representación sea única, con

• "0 <= microsegundos < 1000000"

• "0 <= segundos< 3600*24" (el número de segundos en un día)

• "-999999999 <= days <= 999999999"

El siguiente ejemplo ilustra cómo cualquier argumento además de days, seconds y microseconds se "fusionan" y normalizan en esos tres atributos resultantes:

  >>> import datetime as dt
  >>> delta = dt.timedelta(
  ...     days=50,
  ...     seconds=27,
  ...     microseconds=10,
  ...     milliseconds=29000,
  ...     minutes=5,
  ...     hours=8,
  ...     weeks=2
  ... )
  >>> # Only days, seconds, and microseconds remain
  >>> delta
  datetime.timedelta(days=64, seconds=29156, microseconds=10)

Truco:

 "import datetime as dt" instead of "import datetime" or "from
 datetime import datetime" to avoid confusion between the module
 and the class. See How I Import Python’s datetime Module.

Si algún argumento es flotante y hay microsegundos fraccionarios, los microsegundos fraccionarios que quedan de todos los argumentos se combinan y su suma se redondea al microsegundo más cercano utilizando el desempate de medio redondeo a par. Si ningún argumento es flotante, los procesos de conversión y normalización son exactos (no se pierde información).

Si el valor normalizado de los días se encuentra fuera del rango indicado, se lanza "OverflowError".

Tenga en cuenta que la normalización de los valores negativos puede ser sorprendente al principio. Por ejemplo:

  >>> import datetime as dt
  >>> d = dt.timedelta(microseconds=-1)
  >>> (d.days, d.seconds, d.microseconds)
  (-1, 86399, 999999)

Since the string representation of "timedelta" objects can be confusing, use the following recipe to produce a more readable format:

  >>> def pretty_timedelta(td):
  ...     if td.days >= 0:
  ...         return str(td)
  ...     return f'-({-td!s})'
  ...
  >>> d = timedelta(hours=-1)
  >>> str(d)  # not human-friendly
  '-1 day, 23:00:00'
  >>> pretty_timedelta(d)
  '-(1:00:00)'

Atributos de clase:

timedelta.min

El objeto más negativo en "timedelta", "timedelta(-999999999)".

timedelta.max

El objeto más positivo de la "timedelta", "timedelta(days=999999999, hours=23, minutes=59, seconds=59, microseconds=999999)".

timedelta.resolution

La diferencia más pequeña posible entre los objetos no iguales "timedelta" "timedelta(microseconds=1)".

Note that, because of normalization, "timedelta.max" is greater than "-timedelta.min". "-timedelta.max" is not representable as a "timedelta" object.

Atributos de instancia (solo lectura):

timedelta.days

Between -999,999,999 and 999,999,999 inclusive.

timedelta.seconds

Between 0 and 86,399 inclusive.

Prudencia:

 It is a somewhat common bug for code to unintentionally use this
 attribute when it is actually intended to get a "total_seconds()"
 value instead:

    >>> import datetime as dt
    >>> duration = dt.timedelta(seconds=11235813)
    >>> duration.days, duration.seconds
    (130, 3813)
    >>> duration.total_seconds()
    11235813.0

timedelta.microseconds

Between 0 and 999,999 inclusive.

Operaciones soportadas:

+----------------------------------+-------------------------------------------------+ | Operación | Resultado | |==================================|=================================================| | "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)(6) |#

| "t1 = t2 * i o 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 o t1 = f * t2" | Delta multiplicado por un número decimal. El | | | resultado se redondea al múltiplo mas cercano | | | de timedelta.resolution usando redondeo de |

| | medio a par. |#

| "f = t2 / t3" | Division (3) of overall duration "t2" by |

| | interval unit "t3". Returns a "float" object. |#

| "t1 = t2 / f o t1 = t2 / i" | Delta dividido por un número decimal o un | | | entero. El resultado se redondea al múltiplo | | | más cercano de timedelta.resolution usando |

| | redondeo de medio a par. |#

| "t1 = t2 // i" o "t1 = t2 // t3" | El piso (floor) se calcula y el resto (si lo | | | hay) se descarta. En el segundo caso, se |

| | retorna un entero. (3) |#

| "t1 = t2 % t3" | El resto se calcula como un objeto "timedelta". |

| | (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. |#

| "+t1" | Retorna un objeto "timedelta" con el mismo |

| | valor. (2) |#

| "-t1" | Equivalent to "timedelta(-t1.days, -t1.seconds, |

| | -t1.microseconds)", and to "t1 * -1". (1)(4) |#

| "abs(t)" | Equivalent to "+t" when "t.days >= 0", and to |

| | "-t" when "t.days < 0". (2) |#

| "str(t)" | Retorna una cadena de caracteres en la forma | | | "[D day[s], ][H]H:MM:SS[.UUUUUU]", donde D es |

| | negativo para negativo "t". (5) |#

| "repr(t)" | Retorna una representación de cadena del objeto | | | "timedelta" como una llamada de constructor con |

| | valores de atributos canónicos. |#

Notas:

1. Esto es exacto pero puede desbordarse.

2. Esto es exacto pero no puede desbordarse.

3. Division by zero raises "ZeroDivisionError".

4. "-timedelta.max" is not representable as a "timedelta" object.

5. Las representaciones de cadena de caracteres de los objetos "timedelta" se normalizan de manera similar a su representación interna. Esto conduce a resultados algo inusuales para timedeltas negativos. Por ejemplo:

   timedelta(hours=-5) datetime.timedelta(days=-1, seconds=68400) print(_) -1 day, 19:00:00

6. La expresión "t2 - t3" siempre será igual a la expresión "t2 + (-t3)" excepto cuando t3 es igual a "timedelta.max"; en ese caso, el primero producirá un resultado mientras que el segundo se desbordará.

Además de las operaciones enumeradas anteriormente, los objetos "timedelta" admiten ciertas sumas y restas con objetos "date" y "datetime" (ver más abajo).

Distinto en la versión 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.

"timedelta" objects support equality and order comparisons.

En contextos booleanos, un objeto "timedelta" se considera verdadero si y solo si no es igual a "timedelta (0)".

Métodos de instancia:

timedelta.total_seconds()

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 (for example, "td / timedelta(microseconds=1)").

Tenga en cuenta que para intervalos de tiempo muy largos (más de 270 años en la mayoría de las plataformas) este método perderá precisión de microsegundos.

Added in version 3.2.

Examples of usage: "timedelta"#

Ejemplos adicionales de normalización:

Components of another_year add up to exactly 365 days#

import datetime as dt year = dt.timedelta(days=365) another_year = dt.timedelta(weeks=40, days=84, hours=23, ... minutes=50, seconds=600) year == another_year True year.total_seconds() 31536000.0

Ejemplos de "timedelta" aritmética:

import datetime as dt year = dt.timedelta(days=365) ten_years = 10 * year ten_years datetime.timedelta(days=3650) ten_years.days // 365 10 nine_years = ten_years - year nine_years datetime.timedelta(days=3285) three_years = nine_years // 3 three_years, three_years.days // 365 (datetime.timedelta(days=1095), 3)

"date" objects#

El objeto "date" representa una fecha (año, mes y día) en un calendario idealizado, el calendario gregoriano actual se extiende indefinidamente en ambas direcciones.

El 1 de enero del año 1 se llama día número 1, el 2 de enero del año 1 se llama día número 2, y así sucesivamente. [2]

class datetime.date(year, month, day)

Todos los argumentos son obligatorios. Los argumentos deben ser enteros, en los siguientes rangos:

• "MINYEAR <= year <= MAXYEAR"

• "1 <= month <= 12"

• "1 <= day <= number of days in the given month and year"

Si se proporciona un argumento fuera de esos rangos, "ValueError" se genera.

Otros constructores, todos los métodos de clase:

classmethod date.today()

Retorna la fecha local actual.

Esto es equivalente a "date.fromtimestamp(time.time())".

classmethod date.fromtimestamp(timestamp)

Return the local date corresponding to the POSIX timestamp, such as is returned by "time.time()".

Esto puede generar "OverflowError", si la marca de tiempo está fuera del rango de valores admitidos por la plataforma C "localtime()", y "OSError" en "localtime()" falla . Es común que esto se restrinja a años desde 1970 hasta 2038. Tenga en cuenta que en los sistemas que no son POSIX que incluyen segundos bisiestos en su noción de marca de tiempo, los segundos bisiestos son ignorados por "fromtimestamp()".

Distinto en la versión 3.3: Se genera "OverflowError" en lugar de "ValueError" si la marca de tiempo está fuera del rango de valores admitidos por la plataforma C "localtime()". Se genera "OSError" en lugar de "ValueError" cuando "localtime()", falla.

classmethod date.fromordinal(ordinal)

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, with the following exceptions:

1. Reduced precision dates are not currently supported ("YYYY-MM", "YYYY").

2. Extended date representations are not currently supported ("±YYYYYY-MM-DD").

3. Ordinal dates are not currently supported ("YYYY-OOO").

Ejemplos:

  >>> import datetime as dt
  >>> dt.date.fromisoformat('2019-12-04')
  datetime.date(2019, 12, 4)
  >>> dt.date.fromisoformat('20191204')
  datetime.date(2019, 12, 4)
  >>> dt.date.fromisoformat('2021-W01-1')
  datetime.date(2021, 1, 4)

Added in version 3.7.

Distinto en la versión 3.11: Anteriormente, este método solo admitía el formato "YYYY-MM-DD".

classmethod date.fromisocalendar(year, week, day)

Return a "date" corresponding to the ISO calendar date specified by year, week and day. This is the inverse of the function "date.isocalendar()".

Added in version 3.8.

classmethod date.strptime(date_string, format)

Return a "date" corresponding to date_string, parsed according to format. This is equivalent to:

  date(*(time.strptime(date_string, format)[0:3]))

"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. See also strftime() and strptime() behavior and "date.fromisoformat()".

Nota:

 If *format* specifies a day of month without a year a
 "DeprecationWarning" is emitted.  This is to avoid a quadrennial
 leap year bug in code seeking to parse only a month and day as
 the default year used in absence of one in the format is not a
 leap year. Such *format* values may raise an error as of Python
 3.15.  The workaround is to always include a year in your
 *format*.  If parsing *date_string* values that do not have a
 year, explicitly add a year that is a leap year before parsing:

    >>> import datetime as dt
    >>> date_string = "02/29"
    >>> when = dt.date.strptime(f"{date_string};1984", "%m/%d;%Y")  # Avoids leap year bug.
    >>> when.strftime("%B %d")
    'February 29'

Added in version 3.14.

Atributos de clase:

date.min

La fecha representable más antigua, "date(MINYEAR, 1, 1)".

date.max

La última fecha representable, "date(MAXYEAR, 12, 31)".

date.resolution

La menor diferencia entre objetos de fecha no iguales, "timedelta(days=1)".

Atributos de instancia (solo lectura):

date.year

Entre "MINYEAR" y "MAXYEAR" inclusive.

date.month

Entre 1 y 12 inclusive.

date.day

Entre 1 y el número de días en el mes dado del año dado.

Operaciones soportadas:

+---------------------------------+------------------------------------------------+ | Operación | Resultado | |=================================|================================================| | "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" | (3) |#

| "date1 == date2" "date1 != | Equality comparison. (4) |

| date2" | |#

| "date1 < date2" "date1 > date2" | Order comparison. (5) | | "date1 <= date2" "date1 >= | |

| date2" | |#

Notas:

1. date2 se mueve hacia adelante en el tiempo si "timedelta.days > 0", o hacia atrás si "timedelta.days < 0". Después "date2 - date1 == timedelta. days". "timedelta.seconds" y "timedelta.microseconds" se ignoran. "OverflowError" se lanza si "date2.year" sería menor que "MINYEAR" o mayor que "MAXYEAR".

2. "timedelta.seconds" y "timedelta.microseconds" son ignorados.

3. This is exact, and cannot overflow. "timedelta.seconds" and "timedelta.microseconds" are 0, and "date2 + timedelta == date1" after.

4. "date" objects are equal if they represent the same date.

"date" objects that are not also "datetime" instances are never equal to "datetime" objects, even if they represent the same date.

5. date1 is considered less than date2 when date1 precedes date2 in time. In other words, "date1 < date2" if and only if "date1.toordinal() < date2.toordinal()".

Order comparison between a "date" object that is not also a "datetime" instance and a "datetime" object raises "TypeError".

Distinto en la versión 3.13: Comparison between "datetime" object and an instance of the "date" subclass that is not a "datetime" subclass no longer converts the latter to "date", ignoring the time part and the time zone. The default behavior can be changed by overriding the special comparison methods in subclasses.

En contextos booleanos, todos los objetos "date" se consideran verdaderos.

Métodos de instancia:

date.replace(year=self.year, month=self.month, day=self.day)

Return a new "date" object with the same values, but with specified parameters updated.

Ejemplo:

  >>> import datetime as dt
  >>> d = dt.date(2002, 12, 31)
  >>> d.replace(day=26)
  datetime.date(2002, 12, 26)

The generic function "copy.replace()" also supports "date" objects.

date.timetuple()

Retorna una "time.struct_time" como la que retorna "time.localtime()".

Las horas, minutos y segundos son 0, y el indicador DST es -1.

"d.timetuple()" es equivalente a:

  time.struct_time((d.year, d.month, d.day, 0, 0, 0, d.weekday(), yday, -1))

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.

date.toordinal()

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".

date.weekday()

Retorna el día de la semana como un número entero, donde el lunes es 0 y el domingo es 6. Por ejemplo, "date(2002, 12, 4).weekday() == 2", un miércoles. Ver también "isoweekday()".

date.isoweekday()

Retorna el día de la semana como un número entero, donde el lunes es 1 y el domingo es 7. Por ejemplo, "date(2002, 12, 4).isoweekday() == 3", un miércoles. Ver también "weekday()", "isocalendar()".

date.isocalendar()

Retorna un objeto named tuple con tres componentes: "year", "week" y "weekday".

El calendario ISO es una variante amplia utilizada del calendario gregoriano. [3]

El año ISO consta de 52 o 53 semanas completas, y donde una semana comienza un lunes y termina un domingo. La primera semana de un año ISO es la primera semana calendario (gregoriana) de un año que contiene un jueves. Esto se llama semana número 1, y el año ISO de ese jueves es el mismo que el año gregoriano.

Por ejemplo, 2004 comienza en jueves, por lo que la primera semana del año ISO 2004 comienza el lunes 29 de diciembre de 2003 y termina el domingo 4 de enero de 2004

  >>> import datetime as dt
  >>> dt.date(2003, 12, 29).isocalendar()
  datetime.IsoCalendarDate(year=2004, week=1, weekday=1)
  >>> dt.date(2004, 1, 4).isocalendar()
  datetime.IsoCalendarDate(year=2004, week=1, weekday=7)

Distinto en la versión 3.9: El resultado cambió de una tupla a un named tuple.

date.isoformat()

Retorna una cadena de caracteres que representa la fecha en formato ISO 8601, "AAAA-MM-DD":

  >>> import datetime as dt
  >>> dt.date(2002, 12, 4).isoformat()
  '2002-12-04'

date.str()

For a date "d", "str(d)" is equivalent to "d.isoformat()".

date.ctime()

Retorna una cadena de caracteres que representa la fecha:

  >>> import datetime as dt
  >>> dt.date(2002, 12, 4).ctime()
  'Wed Dec  4 00:00:00 2002'

"d.ctime()" es equivalente a:

  time.ctime(time.mktime(d.timetuple()))

en plataformas donde la función nativa C "ctime()" (donde "time.ctime()" llama, pero que "date.ctime()" no se llama) se ajusta al estándar C.

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. See also strftime() and strptime() behavior and "date.isoformat()".

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()". See also strftime() and strptime() behavior and "date.isoformat()".

Examples of usage: "date"#

Ejemplo de contar días para un evento:

import time import datetime as dt today = dt.date.today() today datetime.date(2007, 12, 5) today == dt.date.fromtimestamp(time.time()) True my_birthday = dt.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

Más ejemplos de trabajo con "date":

import datetime as dt d = dt.date.fromordinal(730920) # 730920th day after 1. 1. 0001 d datetime.date(2002, 3, 11)

Methods related to formatting string output#

d.isoformat() '2002-03-11' d.strftime("%d/%m/%y") '11/03/02' d.strftime("%A %d. %B %Y") 'Monday 11. March 2002' d.ctime() 'Mon Mar 11 00:00:00 2002' 'The {1} is {0:%d}, the {2} is {0:%B}.'.format(d, "day", "month") 'The day is 11, the month is March.'

Methods for extracting 'components' under different calendars#

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 )

A date object is immutable; all operations produce a new object#

d.replace(year=2005) datetime.date(2005, 3, 11)

"datetime" objects#

El objeto "datetime" es un único objeto que contiene toda la información de un objeto "date" y un objeto "time".

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.

Constructor:

class datetime.datetime(year, month, day, hour=0, minute=0, second=0, microsecond=0, tzinfo=None, *, fold=0)

Se requieren los argumentos year, month y day. tzinfo puede ser "None", o una instancia de una subclase "tzinfo". Los argumentos restantes deben ser enteros en los siguientes rangos:

• "MINYEAR <= year <= MAXYEAR",

• "1 <= month <= 12",

• "1 <= day <= number of days in the given month and year",

• "0 <= hour < 24",

• "0 <= minute < 60",

• "0 <= second < 60",

• "0 <= microsecond < 1000000",

• "fold in [0, 1]".

Si se proporciona un argumento fuera de esos rangos, "ValueError" se genera.

Distinto en la versión 3.6: Added the fold parameter.

Otros constructores, todos los métodos de clase:

classmethod datetime.today()

Return the current local date and time, with "tzinfo" "None".

Equivalente a:

  datetime.fromtimestamp(time.time())

Ver también "now()", "fromtimestamp()".

Este método es funciona como "now()", pero sin un parámetro "tz".

classmethod datetime.now(tz=None)

Retorna la fecha y hora local actual.

Si el argumento opcional tz es "None" o no se especifica, es como "today()", pero, si es posible, proporciona más precisión de la que se puede obtener al pasar por "time.time()" marca de tiempo (por ejemplo, esto puede ser posible en plataformas que suministran la función C "gettimeofday()").

Si tz no es "None", debe ser una instancia de una subclase "tzinfo", y la fecha y hora actuales se convierten en la zona horaria de tz.

Esta función es preferible a "today()" y "utcnow()".

Nota:

 Subsequent calls to "datetime.now()" may return the same instant
 depending on the precision of the underlying clock.

classmethod datetime.utcnow()

Retorna la fecha y hora UTC actual, con "tzinfo" "None".

Esto es como "now()", pero retorna la fecha y hora UTC actual, como un objeto naíf (naive): "datetime". Se puede obtener una fecha y hora UTC actual consciente (aware) llamando a "datetime.now (timezone.utc)". Ver también "now()".

Advertencia:

 Debido a que los objetos naífs (*naive*) de "datetime" son
 tratados por muchos métodos de "datetime" como horas locales, se
 prefiere usar fechas y horas conscientes(*aware*) para
 representar las horas en UTC. Como tal, la forma recomendada de
 crear un objeto que represente la hora actual en UTC es llamando
 a "datetime.now(timezone.utc)".

Obsoleto desde la versión 3.12: Use "datetime.now()" with "UTC" instead.

classmethod datetime.fromtimestamp(timestamp, tz=None)

Retorna la fecha y hora local correspondiente a la marca de tiempo POSIX, tal como la retorna "time.time()". Si el argumento opcional tz es "None" o no se especifica, la marca de tiempo se convierte a la fecha y hora local de la plataforma, y el objeto retornado "datetime" es naíf (naive).

Si tz no es "None", debe ser una instancia de una subclase "tzinfo", y la fecha y hora actuales se convierten en la zona horaria de tz.

"fromtimestamp()" puede aumentar "OverflowError", si la marca de tiempo está fuera del rango de valores admitidos por la plataforma C "localtime()" o "gmtime()", y "OSError" en "localtime()" o "gmtime()" falla. Es común que esto se restrinja a los años 1970 a 2038. Tenga en cuenta que en los sistemas que no son POSIX que incluyen segundos bisiestos en su noción de marca de tiempo, los segundos bisiestos son ignorados por "fromtimestamp()", y luego es posible tener dos marcas de tiempo que difieren en un segundo que producen objetos idénticos "datetime". Se prefiere este método sobre "utcfromtimestamp()".

Distinto en la versión 3.3: Se genera "OverflowError" en lugar de "ValueError" si la marca de tiempo está fuera del rango de valores admitidos por la plataforma C "localtime()" o "gmtime()". genera "OSError" en lugar de la función "ValueError" en "localtime()" o error "gmtime()".

Distinto en la versión 3.6: "fromtimestamp()" puede retornar instancias con "fold" establecido en 1.

classmethod datetime.utcfromtimestamp(timestamp)

Retorna el UTC "datetime" correspondiente a la marca de tiempo POSIX, con "tzinfo" "None". (El objeto resultante es naíf (naive).)

Esto puede generar "OverflowError", si la marca de tiempo está fuera del rango de valores admitidos por la plataforma C "gmtime()", y error en "OSError" en "gmtime()". Es común que esto se restrinja a los años entre1970 a 2038.

Para conocer un objeto "datetime", llama a "fromtimestamp()":

  datetime.fromtimestamp(timestamp, timezone.utc)

En las plataformas compatibles con POSIX, es equivalente a la siguiente expresión:

  datetime(1970, 1, 1, tzinfo=timezone.utc) + timedelta(seconds=timestamp)

excepto que la última fórmula siempre admite el rango de años completo: entre "MINYEAR" y "MAXYEAR" inclusive.

Advertencia:

 Debido a que los objetos naíf (*naive*) de "datetime" son
 tratados por muchos métodos de "datetime" como horas locales, se
 prefiere usar fechas y horas conscientes para representar las
 horas en UTC. Como tal, la forma recomendada de crear un objeto
 que represente una marca de tiempo específica en UTC es llamando
 a "datetime.fromtimestamp(timestamp, tz=timezone.utc)".

Distinto en la versión 3.3: Se genera "OverflowError" en lugar de "ValueError" si la marca de tiempo está fuera del rango de valores admitidos por la plataforma C "gmtime()". genera "OSError" en lugar de "ValueError" en el error de "gmtime()".

Distinto en la versión 3.15: Accepts any real number as timestamp, not only integer or float.

Obsoleto desde la versión 3.12: Use "datetime.fromtimestamp()" with "UTC" instead.

classmethod datetime.fromordinal(ordinal)

Se genera "datetime" correspondiente al ordinal del proléptico gregoriano, donde el 1 de enero del año 1 tiene ordinal 1. "ValueError" se genera a menos que "1 <= ordinal <= datetime.max.toordinal()". La hora, minuto, segundo y microsegundo del resultado son todos 0, y "tzinfo" es "None".

classmethod datetime.combine(date, time, tzinfo=time.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. If the date argument is a "datetime" object, its time components and "tzinfo" attributes are ignored.

For any "datetime" object "d", "d == datetime.combine(d.date(), d.time(), d.tzinfo)".

Distinto en la versión 3.6: Se agregó el argumento tzinfo.

classmethod datetime.fromisoformat(date_string)

Devuelve un "datetime" correspondiente a un date_string en cualquier formato ISO 8601 válido, con las siguientes excepciones:

1. Las compensaciones de zona horaria pueden tener fracciones de segundo.

2. El separador "T" se puede reemplazar por cualquier carácter Unicode único.

3. No se admiten fracciones de horas y minutos.

4. Reduced precision dates are not currently supported ("YYYY-MM", "YYYY").

5. Extended date representations are not currently supported ("±YYYYYY-MM-DD").

6. Ordinal dates are not currently supported ("YYYY-OOO").

Ejemplos:

  >>> import datetime as dt
  >>> dt.datetime.fromisoformat('2011-11-04')
  datetime.datetime(2011, 11, 4, 0, 0)
  >>> dt.datetime.fromisoformat('20111104')
  datetime.datetime(2011, 11, 4, 0, 0)
  >>> dt.datetime.fromisoformat('2011-11-04T00:05:23')
  datetime.datetime(2011, 11, 4, 0, 5, 23)
  >>> dt.datetime.fromisoformat('2011-11-04T00:05:23Z')
  datetime.datetime(2011, 11, 4, 0, 5, 23, tzinfo=datetime.timezone.utc)
  >>> dt.datetime.fromisoformat('20111104T000523')
  datetime.datetime(2011, 11, 4, 0, 5, 23)
  >>> dt.datetime.fromisoformat('2011-W01-2T00:05:23.283')
  datetime.datetime(2011, 1, 4, 0, 5, 23, 283000)
  >>> dt.datetime.fromisoformat('2011-11-04 00:05:23.283')
  datetime.datetime(2011, 11, 4, 0, 5, 23, 283000)
  >>> dt.datetime.fromisoformat('2011-11-04 00:05:23.283+00:00')
  datetime.datetime(2011, 11, 4, 0, 5, 23, 283000, tzinfo=datetime.timezone.utc)
  >>> dt.datetime.fromisoformat('2011-11-04T00:05:23+04:00')
  datetime.datetime(2011, 11, 4, 0, 5, 23,
      tzinfo=datetime.timezone(datetime.timedelta(seconds=14400)))

Added in version 3.7.

Distinto en la versión 3.11: Previously, this method only supported formats that could be emitted by "date.isoformat()" or "datetime.isoformat()".

classmethod datetime.fromisocalendar(year, week, day)

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()".

Added in version 3.8.

classmethod datetime.strptime(date_string, format)

Retorna "datetime" correspondiente a date_string, analizado según format.

If format does not contain microseconds or time zone information, this is equivalent to:

  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. See also strftime() and strptime() behavior and "datetime.fromisoformat()".

Distinto en la versión 3.13: If format specifies a day of month without a year a "DeprecationWarning" is now emitted. This is to avoid a quadrennial leap year bug in code seeking to parse only a month and day as the default year used in absence of one in the format is not a leap year. Such format values may raise an error as of Python 3.15. The workaround is to always include a year in your format. If parsing date_string values that do not have a year, explicitly add a year that is a leap year before parsing:

  >>> import datetime as dt
  >>> date_string = "02/29"
  >>> when = dt.datetime.strptime(f"{date_string};1984", "%m/%d;%Y")  # Avoids leap year bug.
  >>> when.strftime("%B %d")
  'February 29'

Atributos de clase:

datetime.min

La primera fecha representable "datetime", "datetime(MINYEAR, 1, 1, tzinfo=None)".

datetime.max

La última fecha representable "datetime", "datetime(MAXYEAR, 12, 31, 23, 59, 59, 999999, tzinfo=None)".

datetime.resolution

La diferencia más pequeña posible entre objetos no iguales "datetime", "timedelta(microseconds=1)".

Atributos de instancia (solo lectura):

datetime.year

Entre "MINYEAR" y "MAXYEAR" inclusive.

datetime.month

Entre 1 y 12 inclusive.

datetime.day

Entre 1 y el número de días en el mes dado del año dado.

datetime.hour

En "range(24)".

datetime.minute

En "range(60)".

datetime.second

En "range(60)".

datetime.microsecond

En "range(1000000)".

datetime.tzinfo

El objeto pasó como argumento tzinfo al constructor "datetime", o "None" si no se pasó ninguno.

datetime.fold

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 values 0 and 1 represent, respectively, the earlier and later of the two moments with the same wall time representation.

Added in version 3.6.

Operaciones soportadas:

+-----------------------------------------+----------------------------------+ | Operación | Resultado | |=========================================|==================================|

| "datetime2 = datetime1 + timedelta" | (1) |#

| "datetime2 = datetime1 - timedelta" | (2) |#

| "timedelta = datetime1 - datetime2" | (3) |#

| "datetime1 == datetime2" "datetime1 != | Equality comparison. (4) |

| datetime2" | |#

| "datetime1 < datetime2" "datetime1 > | Order comparison. (5) | | datetime2" "datetime1 <= datetime2" | |

| "datetime1 >= datetime2" | |#

1. "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.

2. 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.

3. 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. The result is "(a.replace(tzinfo=None) - a.utcoffset()) - (b.replace(tzinfo=None) - b.utcoffset())" except that the implementation never overflows.

4. "datetime" objects are equal if they represent the same date and time, taking into account the time zone.

Naive and aware "datetime" objects are never equal.

If both comparands are aware, and have the same "tzinfo" attribute, the "tzinfo" and "fold" attributes are ignored and the base datetimes are compared. If both comparands are aware and have different "tzinfo" attributes, the comparison acts as comparands were first converted to UTC datetimes except that the implementation never overflows. "datetime" instances in a repeated interval are never equal to "datetime" instances in other time zone.

5. datetime1 is considered less than datetime2 when datetime1 precedes datetime2 in time, taking into account the time zone.

Order comparison between naive and aware "datetime" objects raises "TypeError".

If both comparands are aware, and have the same "tzinfo" attribute, the "tzinfo" and "fold" attributes are ignored and the base datetimes are compared. If both comparands are aware and have different "tzinfo" attributes, the comparison acts as comparands were first converted to UTC datetimes except that the implementation never overflows.

Distinto en la versión 3.3: Las comparaciones de igualdad entre las instancias conscientes (aware) y naíf (naive) "datetime" no generan "TypeError".

Distinto en la versión 3.13: Comparison between "datetime" object and an instance of the "date" subclass that is not a "datetime" subclass no longer converts the latter to "date", ignoring the time part and the time zone. The default behavior can be changed by overriding the special comparison methods in subclasses.

Métodos de instancia:

datetime.date()

Retorna el objeto "date" con el mismo año, mes y día.

datetime.time()

Retorna el objeto "time" con la misma hora, minuto, segundo, microsegundo y doblado(fold). "tzinfo" es "None". Ver también método "timetz()".

Distinto en la versión 3.6: El valor de plegado (fold value) se copia en el objeto "time" retornado.

datetime.timetz()

Retorna el objeto "time" con los mismos atributos de hora, minuto, segundo, microsegundo, pliegue y tzinfo. Ver también método "time()".

Distinto en la versión 3.6: El valor de plegado (fold value) se copia en el objeto "time" retornado.

datetime.replace(year=self.year, month=self.month, day=self.day, hour=self.hour, minute=self.minute, second=self.second, microsecond=self.microsecond, tzinfo=self.tzinfo, *, fold=0)

Return a new "datetime" object with the same attributes, but with specified parameters updated. Note that "tzinfo=None" can be specified to create a naive datetime from an aware datetime with no conversion of date and time data.

"datetime" objects are also supported by generic function "copy.replace()".

Distinto en la versión 3.6: Added the fold parameter.

datetime.astimezone(tz=None)

Retorna un objeto "datetime" con el atributo nuevo "tzinfo" tz, ajustando los datos de fecha y hora para que el resultado sea la misma hora UTC que self, pero en hora local tz.

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 time zone.

If called without arguments (or with "tz=None") the system local time zone is assumed for the target time zone. 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 time zone 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 "timezone" 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 "timezone" object from an aware datetime dt without conversion of date and time data, use "dt.replace(tzinfo=None)".

Tenga en cuenta que el método predeterminado "tzinfo.fromutc()" se puede reemplazar en una subclase "tzinfo" para afectar el resultado retornado por "astimezone()". "astimezone()" ignora los casos de error, actúa como:

  def astimezone(self, tz):
      if self.tzinfo is tz:
          return self
      # Convert self to UTC, and attach the new timezone object.
      utc = (self - self.utcoffset()).replace(tzinfo=tz)
      # Convert from UTC to tz's local time.
      return tz.fromutc(utc)

Distinto en la versión 3.3: tz ahora puede ser omitido.

Distinto en la versión 3.6: El método "astimezone()" ahora se puede invocar en instancias naíf (naive) que se supone representan la hora local del sistema.

datetime.utcoffset()

Si "tzinfo" es "None", retorna "None", de lo contrario retorna "self.tzinfo.utcoffset (self)", y genera una excepción si este último no retorna "None" o un objeto "timedelta" con magnitud inferior a un día.

Distinto en la versión 3.7: El desfase UTC no está restringido a un número entero de minutos.

datetime.dst()

Si "tzinfo" es "None", retorna "None", de lo contrario retorna "self.tzinfo.utcoffset (self)", y genera una excepción si este último no retorna "None" o un objeto "timedelta" con magnitud inferior a un día.

Distinto en la versión 3.7: El desfase DST no está restringido a un número entero de minutos.

datetime.tzname()

Si "tzinfo" es "None", retorna "None", de lo contrario retorna "self.tzinfo.tzname(self)", genera una excepción si este último no retorna "None" o un objeto de cadena de caracteres,

datetime.timetuple()

Retorna una "time.struct_time" como la que retorna "time.localtime()".

"d.timetuple()" es equivalente a:

  time.struct_time((d.year, d.month, d.day,
                    d.hour, d.minute, d.second,
                    d.weekday(), yday, dst))

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.

datetime.utctimetuple()

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.

Advertencia:

 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()".

datetime.toordinal()

Retorna el ordinal gregoriano proléptico de la fecha. Lo mismo que "self.date().toordinal()".

datetime.timestamp()

Retorna la marca de tiempo (timestamp) POSIX correspondiente a la instancia "datetime". El valor de retorno es "float" similar al retornado por "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" or "OSError" for times far in the past or far in the future.

Para las instancias de "datetime", el valor de retorno se calcula como:

  (dt - datetime(1970, 1, 1, tzinfo=timezone.utc)).total_seconds()

Nota:

 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 time zone is not
 set to UTC, you can obtain the POSIX timestamp by supplying
 "tzinfo=timezone.utc":

    timestamp = dt.replace(tzinfo=timezone.utc).timestamp()

 o calculando la marca de tiempo (*timestamp*) directamente:

    timestamp = (dt - datetime(1970, 1, 1)) / timedelta(seconds=1)

Added in version 3.3.

Distinto en la versión 3.6: El método "timestamp()" utiliza el atributo "fold" para desambiguar los tiempos durante un intervalo repetido.

datetime.weekday()

Retorna el día de la semana como un entero, donde el lunes es 0 y el domingo es 6. Lo mismo que "self.date().weekday()". Ver también "isoweekday()".

datetime.isoweekday()

Retorna el día de la semana como un número entero, donde el lunes es 1 y el domingo es 7. Lo mismo que "self.date().isoweekday()". Ver también "weekday()", "isocalendar()".

datetime.isocalendar()

Retorna una named tuple con tres componentes: "year", "week", y "weekday". Lo mismo que "self.date().isocalendar()".

datetime.isoformat(sep='T', timespec='auto')

Retorna una cadena de caracteres representando la fecha y la hora en formato ISO 8601:

• "YYYY-MM-DDTHH:MM:SS.ffffff", si "microsecond" no es 0

• "YYYY-MM-DDTHH:MM:SS", si "microsecond" es 0

Si "utcoffset()" no retorna "None", se agrega una cadena de caracteres dando el desplazamiento UTC:

• "YYYY-MM-DDTHH:MM:SS.ffffff+HH:MM[:SS[.ffffff]]", si "microsecond" no es 0

• "YYYY-MM-DDTHH:MM:SS+HH:MM[:SS[.ffffff]]", si "microsecond" es 0

Ejemplos:

  >>> import datetime as dt
  >>> dt.datetime(2019, 5, 18, 15, 17, 8, 132263).isoformat()
  '2019-05-18T15:17:08.132263'
  >>> dt.datetime(2019, 5, 18, 15, 17, tzinfo=dt.timezone.utc).isoformat()
  '2019-05-18T15:17:00+00:00'

El argumento opcional sep (default "’T’") es un separador de un carácter, ubicado entre las porciones de fecha y hora del resultado. Por ejemplo:

  >>> import datetime as dt
  >>> class TZ(dt.tzinfo):
  ...     """A time zone with an arbitrary, constant -06:39 offset."""
  ...     def utcoffset(self, when):
  ...         return dt.timedelta(hours=-6, minutes=-39)
  ...
  >>> dt.datetime(2002, 12, 25, tzinfo=TZ()).isoformat(' ')
  '2002-12-25 00:00:00-06:39'
  >>> dt.datetime(2009, 11, 27, microsecond=100, tzinfo=TZ()).isoformat()
  '2009-11-27T00:00:00.000100-06:39'

El argumento opcional timespec especifica el número de componentes adicionales del tiempo a incluir (el valor predeterminado es "‘auto’"). Puede ser uno de los siguientes:

• "’auto’": Igual que "’seconds’" si "microsecond" es 0, igual que "’microseconds’" de lo contrario.

• "’hours’": incluye el "hour" en el formato de dos dígitos "HH".

• "’minutes’": Incluye "hour" y "minute" en formato "HH:MM".

• "’seconds’": Incluye "hour", "minute", y "second" en formato "HH:MM:SS".

• "’milliseconds’": Incluye tiempo completo, pero trunca la segunda parte fraccionaria a milisegundos. Formato "HH:MM:SS.sss".

• "’microseconds’": Incluye tiempo completo en formato "HH:MM:SS.ffffff".

Nota:

 Los componentes de tiempo excluidos están truncados, no
 redondeados.

"ValueError" lanzará un argumento inválido timespec:

  >>> import datetime as dt
  >>> dt.datetime.now().isoformat(timespec='minutes')
  '2002-12-25T00:00'
  >>> my_datetime = dt.datetime(2015, 1, 1, 12, 30, 59, 0)
  >>> my_datetime.isoformat(timespec='microseconds')
  '2015-01-01T12:30:59.000000'

Distinto en la versión 3.6: Added the timespec parameter.

datetime.str()

For a "datetime" instance "d", "str(d)" is equivalent to "d.isoformat(' ')".

datetime.ctime()

Retorna una cadena de caracteres que representa la fecha y la hora:

  >>> import datetime as dt
  >>> dt.datetime(2002, 12, 4, 20, 30, 40).ctime()
  'Wed Dec  4 20:30:40 2002'

La cadena de salida no incluirá información de zona horaria, independientemente de si la entrada es consciente (aware) o naíf (naive).

"d.ctime()" es equivalente a:

  time.ctime(time.mktime(d.timetuple()))

en plataformas donde la función nativa C "ctime()" (que "time.ctime()" invoca, pero que "datetime.ctime()" no invoca) se ajusta al estándar C.

datetime.strftime(format)

Return a string representing the date and time, controlled by an explicit format string. See also strftime() and strptime() behavior and "datetime.isoformat()".

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()". See also strftime() and strptime() behavior and "datetime.isoformat()".

Examples of usage: "datetime"#

Examples of working with "datetime" objects:

import datetime as dt

Using datetime.combine()#

d = dt.date(2005, 7, 14) t = dt.time(12, 30) dt.datetime.combine(d, t) datetime.datetime(2005, 7, 14, 12, 30)

Using datetime.now()#

dt.datetime.now() datetime.datetime(2007, 12, 6, 16, 29, 43, 79043) # GMT +1 dt.datetime.now(dt.timezone.utc) datetime.datetime(2007, 12, 6, 15, 29, 43, 79060, tzinfo=datetime.timezone.utc)

Using datetime.strptime()#

my_datetime = dt.datetime.strptime("21/11/06 16:30", "%d/%m/%y %H:%M") my_datetime datetime.datetime(2006, 11, 21, 16, 30)

Using datetime.timetuple() to get tuple of all attributes#

tt = my_datetime.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 = my_datetime.isocalendar() for it in ic: ... print(it) ... 2006 # ISO year 47 # ISO week 2 # ISO weekday

Formatting a datetime#

my_datetime.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(my_datetime, "day", "month", "time") 'The day is 21, the month is November, the time is 04:30PM.'

El siguiente ejemplo define una subclase "tzinfo" que captura la información de zona horaria de Kabul, Afganistán, que utilizó +4 UTC hasta 1945 y +4:30 UTC a partir de entonces:

import datetime as dt

class KabulTz(dt.tzinfo): # Kabul used +4 until 1945, when they moved to +4:30 UTC_MOVE_DATE = dt.datetime(1944, 12, 31, 20, tzinfo=dt.timezone.utc)

   def utcoffset(self, when):
       if when.year < 1945:
           return dt.timedelta(hours=4)
       elif (1945, 1, 1, 0, 0) <= when.timetuple()[:5] < (1945, 1, 1, 0, 30):
           # An ambiguous ("imaginary") half-hour range representing
           # a 'fold' in time due to the shift from +4 to +4:30.
           # If when falls in the imaginary range, use fold to decide how
           # to resolve. See PEP 495.
           return dt.timedelta(hours=4, minutes=(30 if when.fold else 0))
       else:
           return dt.timedelta(hours=4, minutes=30)

   def fromutc(self, when):
       # Follow same validations as in datetime.tzinfo
       if not isinstance(when, dt.datetime):
           raise TypeError("fromutc() requires a datetime argument")
       if when.tzinfo is not self:
           raise ValueError("when.tzinfo is not self")

       # A custom implementation is required for fromutc as
       # the input to this function is a datetime with utc values
       # but with a tzinfo set to self.
       # See datetime.astimezone or fromtimestamp.
       if when.replace(tzinfo=dt.timezone.utc) >= self.UTC_MOVE_DATE:
           return when + dt.timedelta(hours=4, minutes=30)
       else:
           return when + dt.timedelta(hours=4)

   def dst(self, when):
       # Kabul does not observe daylight saving time.
       return dt.timedelta(0)

   def tzname(self, when):
       if when >= self.UTC_MOVE_DATE:
           return "+04:30"
       return "+04"

Uso de "KabulTz" desde arriba

tz1 = KabulTz()

Datetime before the change#

dt1 = dt.datetime(1900, 11, 21, 16, 30, tzinfo=tz1) print(dt1.utcoffset()) 4:00:00

Datetime after the change#

dt2 = dt.datetime(2006, 6, 14, 13, 0, tzinfo=tz1) print(dt2.utcoffset()) 4:30:00

Convert datetime to another time zone#

dt3 = dt2.astimezone(dt.timezone.utc) dt3 datetime.datetime(2006, 6, 14, 8, 30, tzinfo=datetime.timezone.utc) dt2 datetime.datetime(2006, 6, 14, 13, 0, tzinfo=KabulTz()) dt2 == dt3 True

"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)

Todos los argumentos son opcionales. tzinfo puede ser "None", o una instancia de una subclase "tzinfo". Los argumentos restantes deben ser enteros en los siguientes rangos:

• "0 <= hour < 24",

• "0 <= minute < 60",

• "0 <= second < 60",

• "0 <= microsecond < 1000000",

• "fold in [0, 1]".

If an argument outside those ranges is given, "ValueError" is raised. All default to 0 except tzinfo, which defaults to "None".

Atributos de clase:

time.min

El primero representable "time",time (0, 0, 0, 0).

time.max

El último representable "time", "time(23, 59, 59, 999999)".

time.resolution

La diferencia más pequeña posible entre los objetos no iguales "time", "timedelta(microseconds=1)", aunque tenga en cuenta que la aritmética en objetos "time" no es compatible.

Atributos de instancia (solo lectura):

time.hour

En "range(24)".

time.minute

En "range(60)".

time.second

En "range(60)".

time.microsecond

En "range(1000000)".

time.tzinfo

El objeto pasado como argumento tzinfo al constructor de la clase "time" , o "None" si no se pasó ninguno.

time.fold

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 values 0 and 1 represent, respectively, the earlier and later of the two moments with the same wall time representation.

Added in version 3.6.

"time" objects support equality and order comparisons, where "a" is considered less than "b" when "a" precedes "b" in time.

Naive and aware "time" objects are never equal. Order comparison between naive and aware "time" objects raises "TypeError".

If both comparands are aware, and have the same "tzinfo" attribute, the "tzinfo" and "fold" attributes are 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()").

Distinto en la versión 3.3: Equality comparisons between aware and naive "time" instances don't raise "TypeError".

En contextos booleanos, un objeto "time" siempre se considera verdadero.

Distinto en la versión 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 more information.

Other constructors:

classmethod time.fromisoformat(time_string)

Devuelve un "time" correspondiente a un time_string en cualquier formato ISO 8601 válido, con las siguientes excepciones:

1. Las compensaciones de zona horaria pueden tener fracciones de segundo.

2. No se requiere el "T" inicial, que normalmente se requiere en los casos en que puede haber ambigüedad entre una fecha y una hora.

3. Las fracciones de segundo pueden tener cualquier número de dígitos (cualquier número más allá de 6 será truncado).

4. No se admiten fracciones de horas y minutos.

Examples:

  >>> import datetime as dt
  >>> dt.time.fromisoformat('04:23:01')
  datetime.time(4, 23, 1)
  >>> dt.time.fromisoformat('T04:23:01')
  datetime.time(4, 23, 1)
  >>> dt.time.fromisoformat('T042301')
  datetime.time(4, 23, 1)
  >>> dt.time.fromisoformat('04:23:01.000384')
  datetime.time(4, 23, 1, 384)
  >>> dt.time.fromisoformat('04:23:01,000384')
  datetime.time(4, 23, 1, 384)
  >>> dt.time.fromisoformat('04:23:01+04:00')
  datetime.time(4, 23, 1, tzinfo=datetime.timezone(datetime.timedelta(seconds=14400)))
  >>> dt.time.fromisoformat('04:23:01Z')
  datetime.time(4, 23, 1, tzinfo=datetime.timezone.utc)
  >>> dt.time.fromisoformat('04:23:01+00:00')
  datetime.time(4, 23, 1, tzinfo=datetime.timezone.utc)

Added in version 3.7.

Distinto en la versión 3.11: Previously, this method only supported formats that could be emitted by "time.isoformat()".

classmethod time.strptime(date_string, format)

Return a "time" corresponding to date_string, parsed according to format.

If format does not contain microseconds or timezone information, this is equivalent to:

  time(*(time.strptime(date_string, format)[3:6]))

"ValueError" is raised if the date_string and format cannot be parsed by "time.strptime()" or if it returns a value which is not a time tuple. See also strftime() and strptime() behavior and "time.fromisoformat()".

Added in version 3.14.

Métodos de instancia:

time.replace(hour=self.hour, minute=self.minute, second=self.second, microsecond=self.microsecond, tzinfo=self.tzinfo, *, fold=0)

Return a new "time" with the same values, but with specified parameters updated. Note that "tzinfo=None" can be specified to create a naive "time" from an aware "time", without conversion of the time data.

"time" objects are also supported by generic function "copy.replace()".

Distinto en la versión 3.6: Added the fold parameter.

time.isoformat(timespec='auto')

Retorna una cadena que representa la hora en formato ISO 8601, una de:

• "HH:MM:SS.ffffff", si "microsecond" no es 0

• "HH:MM:SS", si "microsecond" es 0

• "HH:MM:SS.ffffff+HH:MM[:SS[.ffffff]]", si "utcoffset()" no retorna "None"

• "HH:MM:SS+HH:MM[:SS[.ffffff]]", si "microsecond" es 0 y "utcoffset()" no retorna "None"

El argumento opcional timespec especifica el número de componentes adicionales del tiempo a incluir (el valor predeterminado es "‘auto’"). Puede ser uno de los siguientes:

• "’auto’": Igual que "’seconds’" si "microsecond" es 0, igual que "’microseconds’" de lo contrario.

• "’hours’": incluye el "hour" en el formato de dos dígitos "HH".

• "’minutes’": Incluye "hour" y "minute" en formato "HH:MM".

• "’seconds’": Incluye "hour", "minute", y "second" en formato "HH:MM:SS".

• "’milliseconds’": Incluye tiempo completo, pero trunca la segunda parte fraccionaria a milisegundos. Formato "HH:MM:SS.sss".

• "’microseconds’": Incluye tiempo completo en formato "HH:MM:SS.ffffff".

Nota:

 Los componentes de tiempo excluidos están truncados, no
 redondeados.

"ValueError" lanzará un argumento inválido timespec.

Ejemplo:

  >>> import datetime as dt
  >>> dt.time(hour=12, minute=34, second=56, microsecond=123456).isoformat(timespec='minutes')
  '12:34'
  >>> my_time = dt.time(hour=12, minute=34, second=56, microsecond=0)
  >>> my_time.isoformat(timespec='microseconds')
  '12:34:56.000000'
  >>> my_time.isoformat(timespec='auto')
  '12:34:56'

Distinto en la versión 3.6: Added the timespec parameter.

time.str()

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. See also strftime() and strptime() behavior and "time.isoformat()".

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()". See also strftime() and strptime() behavior and "time.isoformat()".

time.utcoffset()

Si "tzinfo" es "None", retorna "None", sino retorna "self.tzinfo.utcoffset(None)", y genera una excepción si este último no retorna "None" o un objeto de "timedelta" con magnitud inferior a un día.

Distinto en la versión 3.7: El desfase UTC no está restringido a un número entero de minutos.

time.dst()

Si "tzinfo" es "None", retorna "None", sino retorna "self.tzinfo.utcoffset(None)", y genera una excepción si este último no retorna "None", o un objeto de "timedelta" con magnitud inferior a un día.

Distinto en la versión 3.7: El desfase DST no está restringido a un número entero de minutos.

time.tzname()

Si "tzinfo" es "None", retorna "None", sino retorna "self.tzinfo.tzname(None)", o genera una excepción si este último no retorna "None" o un objeto de cadena.

Examples of usage: "time"#

Ejemplos de trabajo con el objeto "time":

import datetime as dt class TZ1(dt.tzinfo): ... def utcoffset(self, when): ... return dt.timedelta(hours=1) ... def dst(self, when): ... return dt.timedelta(0) ... def tzname(self, when): ... return "+01:00" ... def repr(self): ... return f"{self.class.name}()" ... t = dt.time(12, 10, 30, tzinfo=TZ1()) t datetime.time(12, 10, 30, tzinfo=TZ1()) t.isoformat() '12:10:30+01:00' t.dst() datetime.timedelta(0) t.tzname() '+01:00' t.strftime("%H:%M:%S %Z") '12:10:30 +01:00' 'The {} is {:%H:%M}.'.format("time", t) 'The time is 12:10.'

"tzinfo" objects#

class datetime.tzinfo

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 time zones 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)

Retorna el desplazamiento de la hora local desde UTC, como un objeto "timedelta" que es positivo al este de UTC. Si la hora local es al oeste de UTC, esto debería ser negativo.

Esto representa el desplazamiento total de UTC; por ejemplo, si un objeto "tzinfo" representa ajustes de zona horaria y DST, "utcoffset()" debería retornar su suma. Si no se conoce el desplazamiento UTC, retorna "None" . De lo contrario, el valor detonado debe ser un objeto de "timedelta" estrictamente entre "-timedelta(hours = 24)" y "timedelta (hours = 24)" (la magnitud del desplazamiento debe ser inferior a un día) La mayoría de las implementaciones de "utcoffset()" probablemente se parecerán a una de estas dos:

  return CONSTANT                 # fixed-offset class
  return CONSTANT + self.dst(dt)  # daylight-aware class

Si "utcoffset()" no retorna "None", "dst()" no debería retornar "None" tampoco.

La implementación por defecto de "utcoffset()" genera "NotImplementedError".

Distinto en la versión 3.7: El desfase UTC no está restringido a un número entero de minutos.

tzinfo.dst(dt)

Retorna el ajuste del horario de verano (DST), como un objeto de "timedelta" o "None" si no se conoce la información de DST.

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.

Una instancia tz de una subclase "tzinfo" que modela los horarios estándar y diurnos debe ser coherente en este sentido:

"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.

La mayoría de las implementaciones de "dst()" probablemente se parecerán a una de estas dos:

  import datetime as dt

  def dst(self, when):
      # a fixed-offset class:  doesn't account for DST
      return dt.timedelta(0)

o:

  import datetime as dt

  def dst(self, when):
      # Code to set dston and dstoff to the time zone's DST
      # transition times based on the input when.year, and expressed
      # in standard local time.

      if dston <= when.replace(tzinfo=None) < dstoff:
          return dt.timedelta(hours=1)
      else:
          return dt.timedelta(0)

La implementación predeterminada de "dst()" genera "NotImplementedError".

Distinto en la versión 3.7: El desfase DST no está restringido a un número entero de minutos.

tzinfo.tzname(dt)

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.

La implementación predeterminada de "tzname()" genera "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".

Cuando se pasa "None", corresponde al diseñador de la clase decidir la mejor respuesta. Por ejemplo, retornar "None" es apropiado si la clase desea decir que los objetos de tiempo no participan en los protocolos "tzinfo". Puede ser más útil que "utcoffset(None)" retorne el desplazamiento UTC estándar, ya que no existe otra convención para descubrir el desplazamiento estándar.

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 time zones.

Hay un método más "tzinfo" que una subclase puede desear anular:

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.

Código de omisión para casos de error, el valor predeterminado "fromutc()" la implementación actúa como

  import datetime as dt

  def fromutc(self, when):
      # raise ValueError error if when.tzinfo is not self
      dtoff = when.utcoffset()
      dtdst = when.dst()
      # raise ValueError if dtoff is None or dtdst is None
      delta = dtoff - dtdst  # this is self's standard offset
      if delta:
          when += delta   # convert to standard local time
          dtdst = when.dst()
          # raise ValueError if dtdst is None
      if dtdst:
          return when + dtdst
      else:
          return when

En el siguiente archivo "tzinfo_examples.py" hay algunos ejemplos de clases "tzinfo":

import datetime as dt

# A class capturing the platform's idea of local time. # (May result in wrong values on historical times in # timezones where UTC offset and/or the DST rules had # changed in the past.) import time

ZERO = dt.timedelta(0) HOUR = dt.timedelta(hours=1) SECOND = dt.timedelta(seconds=1)

STDOFFSET = dt.timedelta(seconds=-time.timezone) if time.daylight: DSTOFFSET = dt.timedelta(seconds=-time.altzone) else: DSTOFFSET = STDOFFSET

DSTDIFF = DSTOFFSET - STDOFFSET

class LocalTimezone(dt.tzinfo):

   def fromutc(self, when):
       assert when.tzinfo is self
       stamp = (when - dt.datetime(1970, 1, 1, tzinfo=self)) // SECOND
       args = time.localtime(stamp)[:6]
       dst_diff = DSTDIFF // SECOND
       # Detect fold
       fold = (args == time.localtime(stamp - dst_diff))
       return dt.datetime(*args, microsecond=when.microsecond,
                          tzinfo=self, fold=fold)

   def utcoffset(self, when):
       if self._isdst(when):
           return DSTOFFSET
       else:
           return STDOFFSET

   def dst(self, when):
       if self._isdst(when):
           return DSTDIFF
       else:
           return ZERO

   def tzname(self, when):
       return time.tzname[self._isdst(when)]

   def _isdst(self, when):
       tt = (when.year, when.month, when.day,
             when.hour, when.minute, when.second,
             when.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(when): days_to_go = 6 - when.weekday() if days_to_go: when += dt.timedelta(days_to_go) return when

# 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 # https://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 = dt.datetime(1, 3, 8, 2) # and ends at 2am (DST time) on the first Sunday of Nov. DSTEND_2007 = dt.datetime(1, 11, 1, 2) # 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) on the last # Sunday of October, which is the first Sunday on or after Oct 25. DSTSTART_1987_2006 = dt.datetime(1, 4, 1, 2) DSTEND_1987_2006 = dt.datetime(1, 10, 25, 2) # 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) # on the last Sunday of October, which is the first Sunday # on or after Oct 25. DSTSTART_1967_1986 = dt.datetime(1, 4, 24, 2) DSTEND_1967_1986 = DSTEND_1987_2006

def us_dst_range(year): # Find start and end times for US DST. For years before 1967, return # start = end for no DST. if 2006 < year: dststart, dstend = DSTSTART_2007, DSTEND_2007 elif 1986 < year < 2007: dststart, dstend = DSTSTART_1987_2006, DSTEND_1987_2006 elif 1966 < year < 1987: dststart, dstend = DSTSTART_1967_1986, DSTEND_1967_1986 else: return (dt.datetime(year, 1, 1), ) * 2

   start = first_sunday_on_or_after(dststart.replace(year=year))
   end = first_sunday_on_or_after(dstend.replace(year=year))
   return start, end

class USTimeZone(dt.tzinfo):

   def __init__(self, hours, reprname, stdname, dstname):
       self.stdoffset = dt.timedelta(hours=hours)
       self.reprname = reprname
       self.stdname = stdname
       self.dstname = dstname

   def __repr__(self):
       return self.reprname

   def tzname(self, when):
       if self.dst(when):
           return self.dstname
       else:
           return self.stdname

   def utcoffset(self, when):
       return self.stdoffset + self.dst(when)

   def dst(self, when):
       if when is None or when.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 when.tzinfo is self.
           return ZERO
       assert when.tzinfo is self
       start, end = us_dst_range(when.year)
       # Can't compare naive to aware objects, so strip the timezone from
       # when first.
       when = when.replace(tzinfo=None)
       if start + HOUR <= when < end - HOUR:
           # DST is in effect.
           return HOUR
       if end - HOUR <= when < end:
           # Fold (an ambiguous hour): use when.fold to disambiguate.
           return ZERO if when.fold else HOUR
       if start <= when < start + HOUR:
           # Gap (a non-existent hour): reverse the fold rule.
           return HOUR if when.fold else ZERO
       # DST is off.
       return ZERO

   def fromutc(self, when):
       assert when.tzinfo is self
       start, end = us_dst_range(when.year)
       start = start.replace(tzinfo=self)
       end = end.replace(tzinfo=self)
       std_time = when + self.stdoffset
       dst_time = std_time + HOUR
       if end <= dst_time < end + HOUR:
           # Repeated hour
           return std_time.replace(fold=1)
       if std_time < start or dst_time >= end:
           # Standard time
           return std_time
       if start <= std_time < end - HOUR:
           # Daylight saving time
           return dst_time

Eastern = USTimeZone(-5, "Eastern", "EST", "EDT") Central = USTimeZone(-6, "Central", "CST", "CDT") Mountain = USTimeZone(-7, "Mountain", "MST", "MDT") Pacific = USTimeZone(-8, "Pacific", "PST", "PDT")

Tenga en cuenta que hay sutilezas inevitables dos veces al año en una subclase "tzinfo" que representa tanto el horario estándar como el horario de verano, en los puntos de transición DST. Para mayor concreción, considere US Eastern (UTC -0500), donde EDT comienza el minuto después de 1:59 (EST) el segundo domingo de marzo y termina el minuto después de 1:59 (EDT) el primer domingo de noviembre

 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

Cuando comienza el horario de verano (la línea de "inicio"),tiempo real transcurrido (wall time) salta de 1:59 a 3:00. Un tiempo de pared de la forma 2: MM realmente no tiene sentido ese día, por lo que "astimezone (Eastern)" no entregará un resultado con "hour == 2" el día en que comienza el horario de verano. Por ejemplo, en la transición de primavera de 2016, obtenemos

import datetime as dt from tzinfo_examples import HOUR, Eastern u0 = dt.datetime(2016, 3, 13, 5, tzinfo=dt.timezone.utc) for i in range(4): ... u = u0 + i*HOUR ... t = u.astimezone(Eastern) ... print(u.time(), 'UTC =', t.time(), t.tzname()) ... 05:00:00 UTC = 00:00:00 EST 06:00:00 UTC = 01:00:00 EST 07:00:00 UTC = 03:00:00 EDT 08:00:00 UTC = 04:00:00 EDT

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:

import datetime as dt from tzinfo_examples import HOUR, Eastern u0 = dt.datetime(2016, 11, 6, 4, tzinfo=dt.timezone.utc) for i in range(4): ... u = u0 + i*HOUR ... t = u.astimezone(Eastern) ... print(u.time(), 'UTC =', t.time(), t.tzname(), t.fold) ... 04:00:00 UTC = 00:00:00 EDT 0 05:00:00 UTC = 01:00:00 EDT 0 06:00:00 UTC = 01:00:00 EST 1 07:00:00 UTC = 02:00:00 EST 0

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)).

Ver también:

 "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 time zone database* (also known as
    the Olson database) to Python, and its usage is recommended.

IANA time zone database La base de datos de zonas horarias (a menudo llamada tz, tzdata o zoneinfo) contiene código y datos que representan el historial de la hora local de muchos lugares representativos de todo el mundo. Se actualiza periódicamente para reflejar los cambios realizados por los cuerpos políticos en los límites de la zona horaria, las compensaciones UTC y las reglas de horario de verano.

"timezone" objects#

The "timezone" class is a subclass of "tzinfo", each instance of which represents a time zone defined by a fixed offset from UTC.

Objects of this class cannot be used to represent time zone 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)

El argumento offset debe especificarse como un objeto de "timedelta" que representa la diferencia entre la hora local y UTC. Debe estar estrictamente entre "-timedelta(horas = 24)" y "timedelta(horas = 24)", de lo contrario "ValueError" se genera.

El argumento name es opcional. Si se especifica, debe ser una cadena de caracteres que se utilizará como el valor retornado por el método "datetime.tzname()".

Added in version 3.2.

Distinto en la versión 3.7: El desfase UTC no está restringido a un número entero de minutos.

timezone.utcoffset(dt)

Retorna el valor fijo especificado cuando se construye la instancia "timezone".

El argumento dt se ignora. El valor de retorno es una instancia de "timedelta" igual a la diferencia entre la hora local y UTC.

Distinto en la versión 3.7: El desfase UTC no está restringido a un número entero de minutos.

timezone.tzname(dt)

Retorna el valor fijo especificado cuando se construye la instancia "timezone".

Si no se proporciona name en el constructor, el nombre retornado por "tzname(dt)" se genera a partir del valor del "offset" de la siguiente manera. Si offset es "timedelta (0)", el nombre es "UTC", de lo contrario es una cadena en el formato "UTC±HH:MM", donde ± es el signo de "offset", HH y MM son dos dígitos de "offset.hours" y "offset.minutes" respectivamente.

Distinto en la versión 3.6: El nombre generado a partir de "offset=timedelta(0)" ahora es simplemente "'UTC'", no "'UTC+00:00'".

timezone.dst(dt)

Siempre retorna "None".

timezone.fromutc(dt)

Retorna "dt + offset". El argumento dt debe ser una instancia consciente (aware) "datetime", con "tzinfo" establecido en "self".

Atributos de clase:

timezone.utc

The UTC time zone, "timezone(timedelta(0))".

"strftime()" and "strptime()" behavior#

"date", "datetime", y "time" los objetos admiten un método "strftime(format)", para crear una cadena que represente el tiempo bajo el control de una cadena de caracteres de formato explícito.

Conversely, the "date.strptime()", "datetime.strptime()" and "time.strptime()" class methods create an object from a string representing the time and a corresponding format string.

The table below provides a high-level comparison of "strftime()" versus "strptime()":

+------------------+----------------------------------------------------------+--------------------------------------------------------------+ | | "strftime" | "strptime" | |==================|==========================================================|==============================================================| | Uso | Convierte objetos en una cadena de caracteres de acuerdo | Parse a string into an object given a corresponding format |

| | con un formato dado | |#

| Tipo de método | Método de instancia | Método de clase |#

| Firma | "strftime(format)" | "strptime(date_string, format)" |#

"strftime()" and "strptime()" format codes#

These methods accept format codes that can be used to parse and format dates:

import datetime as dt dt.datetime.strptime('31/01/22 23:59:59.999999', ... '%d/%m/%y %H:%M:%S.%f') datetime.datetime(2022, 1, 31, 23, 59, 59, 999999) _.strftime('%a %d %b %Y, %I:%M%p') 'Mon 31 Jan 2022, 11:59PM'

La siguiente es una lista de todos los códigos de formato que requiere el estándar 1989 C, y estos funcionan en todas las plataformas con una implementación estándar C.

+-------------+----------------------------------+--------------------------+---------+ | Directiva | Significado | Ejemplo | Notas | |=============|==================================|==========================|=========| | "%a" | Día de la semana como nombre | Sun, Mon, …, Sat | (1) | | | abreviado según la configuración | (en_US); *So, Mo, …, Sa | |

| | regional. | (de_DE)* | |#

| "%A" | Día de la semana como nombre | Sunday, Monday, …, | (1) | | | completo de la localidad. | Saturday (en_US); | | | | | *Sonntag, Montag, …, | |

| | | Samstag (de_DE)* | |#

| "%w" | Día de la semana como un número | 0, 1, …, 6 | | | | decimal, donde 0 es domingo y 6 | | |

| | es sábado. | | |#

| "%d" | Día del mes como un número | 01, 02, …, 31 | (9) |

| | decimal rellenado con ceros. | | |#

| "%b" | Mes como nombre abreviado según | Jan, Feb, …, Dec | (1) | | | la configuración regional. | (en_US); *Jan, Feb, …, | |

| | | Dez (de_DE)* | |#

| "%B" | Mes como nombre completo según | January, February, …, | (1) | | | la configuración regional. | December (en_US); | | | | | *Januar, Februar, …, | |

| | | Dezember (de_DE)* | |#

| "%m" | Mes como un número decimal | 01, 02, …, 12 | (9) |

| | rellenado con ceros. | | |#

| "%y" | Año sin siglo como un número | 00, 01, …, 99 | (9) |

| | decimal rellenado con ceros. | | |#

| "%Y" | Año con siglo como número | 0001, 0002, …, 2013, | (2) |

| | decimal. | 2014, …, 9998, 9999 | |#

| "%H" | Hora (reloj de 24 horas) como un | 00, 01, …, 23 | (9) | | | número decimal rellenado con | | |

| | ceros. | | |#

| "%I" | Hora (reloj de 12 horas) como un | 01, 02, …, 12 | (9) | | | número decimal rellenado con | | |

| | ceros. | | |#

| "%p" | El equivalente de la | AM, PM (en_US); am, pm | (1), | | | configuración regional de AM o | (de_DE) | (3) |

| | PM. | | |#

| "%M" | Minuto como un número decimal | 00, 01, …, 59 | (9) |

| | rellenado con ceros. | | |#

| "%S" | Segundo como un número decimal | 00, 01, …, 59 | (4), |

| | rellenado con ceros. | | (9) |#

| "%f" | Microsegundo como número | 000000, 000001, …, | (5) | | | decimal, con ceros hasta 6 | 999999 | |

| | dígitos. | | |#

| "%z" | Desplazamiento (offset) UTC en | (vacío), +0000, -0400, | (6) | | | la forma "±HHMM[SS[.ffffff]]" | +1030, +063415, | | | | (cadena de caracteres vacía si | -030712.345216 | |

| | el objeto es naíf (naive)). | | |#

| "%Z" | Nombre de zona horaria (cadena | (vacío), UTC, GMT | (6) | | | de caracteres vacía si el objeto | | |

| | es naíf (naive)). | | |#

| "%j" | Día del año como un número | 001, 002, …, 366 | (9) |

| | decimal rellenado con ceros. | | |#

| "%U" | Número de semana del año | 00, 01, …, 53 | (7), | | | (domingo como primer día de la | | (9) | | | semana) como un número decimal | | | | | con ceros. Todos los días de un | | | | | nuevo año que preceden al primer | | | | | domingo se consideran en la | | |

| | semana 0. | | |#

| "%W" | Número de semana del año (lunes | 00, 01, …, 53 | (7), | | | como primer día de la semana) | | (9) | | | como un número decimal con | | | | | ceros. Todos los días de un | | | | | nuevo año que preceden al primer | | | | | lunes se consideran en la semana | | |

| | 0. | | |#

| "%c" | Representación apropiada de | Tue Aug 16 21:30:00 | (1) | | | fecha y hora de la configuración | 1988 (en_US); *Di 16 | | | | regional. | Aug 21:30:00 1988 | |

| | | (de_DE)* | |#

| "%x" | Representación de fecha | 08/16/88 (None); | (1) | | | apropiada de la configuración | 08/16/1988 (en_US); | |

| | regional. | 16.08.1988 (de_DE) | |#

| "%X" | Representación de la hora | 21:30:00 (en_US); | (1) | | | apropiada de la configuración | 21:30:00 (de_DE) | |

| | regional. | | |#

| "%%" | Un carácter literal "’%’". | % | |#

Se incluyen varias directivas adicionales no requeridas por el estándar C89 por conveniencia. Todos estos parámetros corresponden a valores de fecha ISO 8601.

+-------------+----------------------------------+--------------------------+---------+ | Directiva | Significado | Ejemplo | Notas | |=============|==================================|==========================|=========| | "%G" | ISO 8601 año con siglo que | 0001, 0002, …, 2013, | (8) | | | representa el año que contiene | 2014, …, 9998, 9999 | | | | la mayor parte de la semana ISO | | |

| | ("%V"). | | |#

| "%u" | ISO 8601 día de la semana como | 1, 2, …, 7 | | | | un número decimal donde 1 es | | |

| | lunes. | | |#

| "%V" | ISO 8601 semana como un número | 01, 02, …, 53 | (8), | | | decimal con lunes como primer | | (9) | | | día de la semana. La semana 01 | | | | | es la semana que contiene el 4 | | |

| | de enero. | | |#

| "%:z" | UTC offset in the form | (empty), +00:00, -04:00, | (6) | | | "±HH:MM[:SS[.ffffff]]" (empty | +10:30, +06:34:15, | |

| | string if the object is naive). | -03:07:12.345216 | |#

These may not be available on all platforms when used with the "strftime()" method. The ISO 8601 year and ISO 8601 week directives are not interchangeable with the year and week number directives above. Calling "strptime()" with incomplete or ambiguous ISO 8601 directives will raise a "ValueError".

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) documentation. There are also differences between platforms in handling of unsupported format specifiers.

Added in version 3.6: "%G", "%u" y "%V" fueron añadidos.

Added in version 3.12: "%:z" was added.

Technical detail#

Broadly speaking, "d.strftime(fmt)" acts like the "time" module's "time.strftime(fmt, d.timetuple())" although not all objects support a "timetuple()" method.

For the "datetime.strptime()" and "date.strptime()" class methods, the default value is "1900-01-01T00:00:00.000": any components not specified in the format string will be pulled from the default value.

Nota:

Format strings without separators can be ambiguous for parsing. For example, with "%Y%m%d", the string "2026111" may be parsed either as "2026-11-01" or as "2026-01-11". Use separators to ensure the input is parsed as intended.

Nota:

When used to parse partial dates lacking a year, "datetime.strptime()" and "date.strptime()" will raise when encountering February 29 because the default year of 1900 is not a leap year. Always add a default leap year to partial date strings before parsing.

import datetime as dt value = "2/29" dt.datetime.strptime(value, "%m/%d") Traceback (most recent call last): ... ValueError: day 29 must be in range 1..28 for month 2 in year 1900 dt.datetime.strptime(f"1904 {value}", "%Y %m/%d") datetime.datetime(1904, 2, 29, 0, 0)

Usar "datetime.strptime(date_string, format)" es equivalente a:

datetime(*(time.strptime(date_string, format)[0:6]))

except when the format includes sub-second components or time zone offset information, which are supported in "datetime.strptime" but are discarded by "time.strptime".

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.

Por la misma razón, el manejo de cadenas de formato que contienen puntos de código Unicode que no se pueden representar en el conjunto de caracteres del entorno local actual también depende de la plataforma. En algunas plataformas, estos puntos de código se conservan intactos en la salida, mientras que en otros "strftime" puede generar "UnicodeError" o retornar una cadena vacía.

Notas:

1. 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 non-ASCII characters.

2. The "strptime()" method can parse years in the full [1, 9999] range, but years < 1000 must be zero-filled to 4-digit width.

Distinto en la versión 3.2: In previous versions, "strftime()" method was restricted to years >= 1900.

Distinto en la versión 3.3: In version 3.2, "strftime()" method was restricted to years >= 1000.

3. When used with the "strptime()" method, the "%p" directive only affects the output hour field if the "%I" directive is used to parse the hour.

4. Unlike the "time" module, the "datetime" module does not support leap seconds.

5. When used with the "strptime()" method, the "%f" directive accepts from one to six digits and zero pads on the right. "%f" is an extension to the set of format characters in the C standard (but implemented separately in datetime objects, and therefore always available).

6. For a naive object, the "%z", "%:z" and "%Z" format codes are replaced by empty strings.

Para un objeto consciente (aware)

"%z" "utcoffset()" is transformed into a string of the form "±HHMM[SS[.ffffff]]", where "HH" is a 2-digit string giving the number of UTC offset hours, "MM" is a 2-digit string giving the number of UTC offset minutes, "SS" is a 2-digit string giving the number of UTC offset seconds and "ffffff" is a 6-digit string giving the number of UTC offset microseconds. The "ffffff" part is omitted when the offset is a whole number of seconds and both the "ffffff" and the "SS" part is omitted when the offset is a whole number of minutes. For example, if "utcoffset()" returns "timedelta(hours=-3, minutes=-30)", "%z" is replaced with the string "'-0330'".

Distinto en la versión 3.7: El desfase UTC no está restringido a un número entero de minutos.

Distinto en la versión 3.7: When the "%z" directive is provided to the "strptime()" method, the UTC offsets can have a colon as a separator between hours, minutes and seconds. For example, "'+01:00:00'" will be parsed as an offset of one hour. In addition, providing "'Z'" is identical to "'+00:00'".

"%:z" Behaves exactly as "%z", but has a colon separator added between hours, minutes and seconds.

"%Z" In "strftime()", "%Z" is replaced by an empty string if "tzname()" returns "None"; otherwise "%Z" is replaced by the returned value, which must be a string.

  "strptime()" only accepts certain values for "%Z":

  1. cualquier valor en "time.tzname" para la configuración
     regional de su máquina

  2. los valores codificados de forma rígida "UTC" y "GMT"

  Entonces, alguien que viva en Japón puede tener "JST", "UTC" y
  "GMT" como valores válidos, pero probablemente no "EST". Lanzará
  "ValueError" para valores no válidos.

Distinto en la versión 3.2: When the "%z" directive is provided to the "strptime()" method, an aware "datetime" object will be produced. The "tzinfo" of the result will be set to a "timezone" instance.

7. When used with the "strptime()" method, "%U" and "%W" are only used in calculations when the day of the week and the calendar year ("%Y") are specified.

8. Similar to "%U" and "%W", "%V" is only used in calculations when the day of the week and the ISO year ("%G") are specified in a "strptime()" format string. Also note that "%G" and "%Y" are not interchangeable.

9. When used with the "strptime()" method, the leading zero is optional for formats "%d", "%m", "%H", "%I", "%M", "%S", "%j", "%U", "%W", and "%V". Format "%y" does require a leading zero.

10. When parsing a month and day using "strptime()", always include a year in the format. If the value you need to parse lacks a year, append an explicit dummy leap year. Otherwise your code will raise an exception when it encounters leap day because the default year used by the parser (1900) is not a leap year. Users run into that bug every leap year.

    month_day = "02/29" dt.datetime.strptime(f"{month_day};1984", "%m/%d;%Y") # No leap year bug. datetime.datetime(1984, 2, 29, 0, 0)

    Deprecated since version 3.13, will be removed in version 3.15: "strptime()" calls using a format string containing a day of month without a year now emit a "DeprecationWarning". In 3.15 or later we may change this into an error or change the default year to a leap year. See gh-70647.

-[ Pie de notas ]-

[1] If, that is, we ignore the effects of relativity.

[2] Esto coincide con la definición del calendario "proléptico gregoriano" en el libro de Dershowitz y Reingold Cálculos calendáricos, donde es el calendario base para todos los cálculos. Consulte el libro sobre algoritmos para convertir entre ordinales gregorianos prolépticos y muchos otros sistemas de calendario.

[3] Consulte guide to the mathematics of the ISO 8601 calendar de R. H. van Gent para obtener una buena explicación.