datetime — Basic date and time types
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datetime
— Basic date and time types¶
Source code: Lib/datetime.py
The datetime
module supplies classes for manipulating dates and times.
While date and time arithmetic is supported, the focus of the implementation is on efficient attribute extraction for output formatting and manipulation.
See also
Modulecalendar
General calendar related functions.
Moduletime
Time access and conversions.
Modulezoneinfo
Concrete time zones representing the IANA time zone database.
Package dateutilThird-party library with expanded time zone and parsing support.
Aware and Naive Objects¶
Date and time objects may be categorized as “aware” or “naive” depending on whether or not they include timezone information.
With sufficient knowledge of applicable algorithmic and political time adjustments, such as time zone and daylight saving time information, an aware object can locate itself relative to other aware objects. An aware object represents a specific moment in time that is not open to interpretation. 1
A naive object does not contain enough information to unambiguously locate itself relative to other date/time objects. Whether a naive object represents Coordinated Universal Time (UTC), local time, or time in some other timezone is purely up to the program, just like it is up to the program whether a particular number represents metres, miles, or mass. Naive objects are easy to understand and to work with, at the cost of ignoring some aspects of reality.
For applications requiring aware objects, datetime
and time
objects have an optional time zone information attribute, tzinfo
, that
can be set to an instance of a subclass of the abstract tzinfo
class.
These tzinfo
objects capture information about the offset from UTC
time, the time zone name, and whether daylight saving time is in effect.
Only one concrete tzinfo
class, the timezone
class, is
supplied by the datetime
module. The timezone
class can
represent simple timezones with fixed offsets from UTC, such as UTC itself or
North American EST and EDT timezones. Supporting timezones at deeper levels of
detail is up to the application. The rules for time adjustment across the
world are more political than rational, change frequently, and there is no
standard suitable for every application aside from UTC.
Constants¶
The datetime
module exports the following constants:
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
.
Available Types¶
class datetime.
date
An idealized naive date, assuming the current Gregorian calendar always was, and
always will be, in effect. Attributes: year
, month
, and
day
.
class datetime.
time
An idealized time, independent of any particular day, assuming that every day
has exactly 24*60*60 seconds. (There is no notion of “leap seconds” here.)
Attributes: hour
, minute
, second
, microsecond
,
and tzinfo
.
class datetime.
datetime
A combination of a date and a time. Attributes: year
, month
,
day
, hour
, minute
, second
, microsecond
,
and tzinfo
.
class datetime.
timedelta
A duration expressing the difference between two date
, time
,
or datetime
instances to microsecond resolution.
class datetime.
tzinfo
An abstract base class for time zone information objects. These are used by the
datetime
and time
classes to provide a customizable notion of
time adjustment (for example, to account for time zone and/or daylight saving
time).
class datetime.
timezone
A class that implements the tzinfo
abstract base class as a
fixed offset from the UTC.
New in version 3.2.
Objects of these types are immutable.
Subclass relationships:
object
timedelta
tzinfo
timezone
time
date
datetime
Common Properties¶
The date
, datetime
, time
, and timezone
types
share these common features:
Objects of these types are immutable.
Objects of these types are hashable, meaning that they can be used as dictionary keys.
Objects of these types support efficient pickling via the
pickle
module.
Determining if an Object is Aware or Naive¶
Objects of the date
type are always naive.
An object of type time
or datetime
may be aware or naive.
A datetime
object d is aware if both of the following hold:
d.tzinfo
is notNone
d.tzinfo.utcoffset(d)
does not returnNone
Otherwise, d is naive.
A time
object t is aware if both of the following hold:
t.tzinfo
is notNone
t.tzinfo.utcoffset(None)
does not returnNone
.
Otherwise, t is naive.
The distinction between aware and naive doesn’t apply to timedelta
objects.
timedelta
Objects¶
A timedelta
object represents a duration, the difference between two
dates or times.
class datetime.
timedelta
(days=0, seconds=0, microseconds=0, milliseconds=0, minutes=0, hours=0, weeks=0)¶
All arguments are optional and default to 0
. Arguments may be integers
or floats, and may be positive or negative.
Only days, seconds and microseconds are stored internally. Arguments are converted to those units:
A millisecond is converted to 1000 microseconds.
A minute is converted to 60 seconds.
An hour is converted to 3600 seconds.
A week is converted to 7 days.
and days, seconds and microseconds are then normalized so that the representation is unique, with
0 <= microseconds < 1000000
0 <= seconds < 3600*24
(the number of seconds in one day)-999999999 <= days <= 999999999
The following example illustrates how any arguments besides days, seconds and microseconds are “merged” and normalized into those three resulting attributes:
>>> from datetime import timedelta
>>> delta = 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)
If any argument is a float and there are fractional microseconds, the fractional microseconds left over from all arguments are combined and their sum is rounded to the nearest microsecond using round-half-to-even tiebreaker. If no argument is a float, the conversion and normalization processes are exact (no information is lost).
If the normalized value of days lies outside the indicated range,
OverflowError
is raised.
Note that normalization of negative values may be surprising at first. For example:
>>> from datetime import timedelta
>>> d = timedelta(microseconds=-1)
>>> (d.days, d.seconds, d.microseconds)
(-1, 86399, 999999)
Class attributes:
timedelta.
min
¶
The most negative timedelta
object, timedelta(-999999999)
.
timedelta.
max
¶
The most positive timedelta
object, timedelta(days=999999999,
hours=23, minutes=59, seconds=59, microseconds=999999)
.
timedelta.
resolution
¶
The smallest possible difference between non-equal timedelta
objects,
timedelta(microseconds=1)
.
Note that, because of normalization, timedelta.max
> -timedelta.min
.
-timedelta.max
is not representable as a timedelta
object.
Instance attributes (read-only):
Attribute |
Value |
---|---|
|
Between -999999999 and 999999999 inclusive |
|
Between 0 and 86399 inclusive |
|
Between 0 and 999999 inclusive |
Supported operations:
Operation |
Result |
---|---|
|
Sum of t2 and t3. Afterwards t1-t2 == t3 and t1-t3 == t2 are true. (1) |
|
Difference of t2 and t3. Afterwards t1 == t2 - t3 and t2 == t1 + t3 are true. (1)(6) |
|
Delta multiplied by an integer.
Afterwards t1 // i == t2 is true,
provided |
In general, t1 * i == t1 * (i-1) + t1 is true. (1) |
|
|
Delta multiplied by a float. The result is rounded to the nearest multiple of timedelta.resolution using round-half-to-even. |
|
Division (3) of overall duration t2 by
interval unit t3. Returns a |
|
Delta divided by a float or an int. The result is rounded to the nearest multiple of timedelta.resolution using round-half-to-even. |
|
The floor is computed and the remainder (if any) is thrown away. In the second case, an integer is returned. (3) |
|
The remainder is computed as a
|
|
Computes the quotient and the remainder:
|
|
Returns a |
|
equivalent to
|
|
equivalent to +t when |
|
Returns a string in the form
|
|
Returns a string representation of the
|
Notes:
This is exact but may overflow.
This is exact and cannot overflow.
Division by 0 raises
ZeroDivisionError
.-timedelta.max is not representable as a
timedelta
object.String representations of
timedelta
objects are normalized similarly to their internal representation. This leads to somewhat unusual results for negative timedeltas. For example:>>> timedelta(hours=-5) datetime.timedelta(days=-1, seconds=68400) >>> print(_) -1 day, 19:00:00
The expression
t2 - t3
will always be equal to the expressiont2 + (-t3)
except when t3 is equal totimedelta.max
; in that case the former will produce a result while the latter will overflow.
In addition to the operations listed above, timedelta
objects support
certain additions and subtractions with date
and datetime
objects (see below).
Changed in version 3.2: Floor division and true division of a timedelta
object by another
timedelta
object are now supported, as are remainder operations and
the divmod()
function. True division and multiplication of a
timedelta
object by a float
object are now supported.
Comparisons of timedelta
objects are supported, with some caveats.
The comparisons ==
or !=
always return a bool
, no matter
the type of the compared object:
>>> from datetime import timedelta
>>> delta1 = timedelta(seconds=57)
>>> delta2 = timedelta(hours=25, seconds=2)
>>> delta2 != delta1
True
>>> delta2 == 5
False
For all other comparisons (such as <
and >
), when a timedelta
object is compared to an object of a different type, TypeError
is raised:
>>> delta2 > delta1
True
>>> delta2 > 5
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: '>' not supported between instances of 'datetime.timedelta' and 'int'
In Boolean contexts, a timedelta
object is
considered to be true if and only if it isn’t equal to timedelta(0)
.
Instance methods:
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 (e.g. td / timedelta(microseconds=1)
).
Note that for very large time intervals (greater than 270 years on most platforms) this method will lose microsecond accuracy.
New in version 3.2.
Examples of usage: timedelta
¶
An additional example of normalization:
>>> # Components of another_year add up to exactly 365 days
>>> from datetime import timedelta
>>> year = timedelta(days=365)
>>> another_year = timedelta(weeks=40, days=84, hours=23,
... minutes=50, seconds=600)
>>> year == another_year
True
>>> year.total_seconds()
31536000.0
Examples of timedelta
arithmetic:
>>> from datetime import timedelta
>>> year = 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¶
A date
object represents a date (year, month and day) in an idealized
calendar, the current Gregorian calendar indefinitely extended in both
directions.
January 1 of year 1 is called day number 1, January 2 of year 1 is called day number 2, and so on. 2
class datetime.
date
(year, month, day)¶
All arguments are required. Arguments must be integers, in the following ranges:
MINYEAR <= year <= MAXYEAR
1 <= month <= 12
1 <= day <= number of days in the given month and year
If an argument outside those ranges is given, ValueError
is raised.
Other constructors, all class methods:
classmethod date.
today
()¶
Return the current local date.
This is equivalent to date.fromtimestamp(time.time())
.
classmethod date.
fromtimestamp
(timestamp)¶
Return the local date corresponding to the POSIX timestamp, such as is
returned by time.time()
.
This may raise OverflowError
, if the timestamp is out
of the range of values supported by the platform C localtime()
function, and OSError
on localtime()
failure.
It’s common for this to be restricted to years from 1970 through 2038. Note
that on non-POSIX systems that include leap seconds in their notion of a
timestamp, leap seconds are ignored by fromtimestamp()
.
Changed in version 3.3: Raise OverflowError
instead of ValueError
if the timestamp
is out of the range of values supported by the platform C
localtime()
function. Raise OSError
instead of
ValueError
on localtime()
failure.
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 the format
YYYY-MM-DD
:
>>> from datetime import date
>>> date.fromisoformat('2019-12-04')
datetime.date(2019, 12, 4)
This is the inverse of date.isoformat()
. It only supports the format
YYYY-MM-DD
.
New in version 3.7.
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()
.
New in version 3.8.
Class attributes:
date.
min
¶
The earliest representable date, date(MINYEAR, 1, 1)
.
date.
max
¶
The latest representable date, date(MAXYEAR, 12, 31)
.
date.
resolution
¶
The smallest possible difference between non-equal date objects,
timedelta(days=1)
.
Instance attributes (read-only):
date.
year
¶
Between MINYEAR
and MAXYEAR
inclusive.
date.
month
¶
Between 1 and 12 inclusive.
date.
day
¶
Between 1 and the number of days in the given month of the given year.
Supported operations:
Operation |
Result |
---|---|
|
date2 is |
|
Computes date2 such that |
|
|
|
date1 is considered less than date2 when date1 precedes date2 in time. (4) |
Notes:
date2 is moved forward in time if
timedelta.days > 0
, or backward iftimedelta.days < 0
. Afterwarddate2 - date1 == timedelta.days
.timedelta.seconds
andtimedelta.microseconds
are ignored.OverflowError
is raised ifdate2.year
would be smaller thanMINYEAR
or larger thanMAXYEAR
.timedelta.seconds
andtimedelta.microseconds
are ignored.This is exact, and cannot overflow. timedelta.seconds and timedelta.microseconds are 0, and date2 + timedelta == date1 after.
In other words,
date1 < date2
if and only ifdate1.toordinal() < date2.toordinal()
. Date comparison raisesTypeError
if the other comparand isn’t also adate
object. However,NotImplemented
is returned instead if the other comparand has atimetuple()
attribute. This hook gives other kinds of date objects a chance at implementing mixed-type comparison. If not, when adate
object is compared to an object of a different type,TypeError
is raised unless the comparison is==
or!=
. The latter cases returnFalse
orTrue
, respectively.
In Boolean contexts, all date
objects are considered to be true.
Instance methods:
date.
replace
(year=self.year, month=self.month, day=self.day)¶
Return a date with the same value, except for those parameters given new values by whichever keyword arguments are specified.
Example:
>>> from datetime import date
>>> d = date(2002, 12, 31)
>>> d.replace(day=26)
datetime.date(2002, 12, 26)
date.
timetuple
()¶
Return a time.struct_time
such as returned by time.localtime()
.
The hours, minutes and seconds are 0, and the DST flag is -1.
d.timetuple()
is equivalent to:
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
()¶
Return the day of the week as an integer, where Monday is 0 and Sunday is 6.
For example, date(2002, 12, 4).weekday() == 2
, a Wednesday. See also
isoweekday()
.
date.
isoweekday
()¶
Return the day of the week as an integer, where Monday is 1 and Sunday is 7.
For example, date(2002, 12, 4).isoweekday() == 3
, a Wednesday. See also
weekday()
, isocalendar()
.
date.
isocalendar
()¶
Return a named tuple object with three components: year
,
week
and weekday
.
The ISO calendar is a widely used variant of the Gregorian calendar. 3
The ISO year consists of 52 or 53 full weeks, and where a week starts on a Monday and ends on a Sunday. The first week of an ISO year is the first (Gregorian) calendar week of a year containing a Thursday. This is called week number 1, and the ISO year of that Thursday is the same as its Gregorian year.
For example, 2004 begins on a Thursday, so the first week of ISO year 2004 begins on Monday, 29 Dec 2003 and ends on Sunday, 4 Jan 2004:
>>> from datetime import date
>>> date(2003, 12, 29).isocalendar()
datetime.IsoCalendarDate(year=2004, week=1, weekday=1)
>>> date(2004, 1, 4).isocalendar()
datetime.IsoCalendarDate(year=2004, week=1, weekday=7)
Changed in version 3.9: Result changed from a tuple to a named tuple.
date.
isoformat
()¶
Return a string representing the date in ISO 8601 format, YYYY-MM-DD
:
>>> from datetime import date
>>> date(2002, 12, 4).isoformat()
'2002-12-04'
This is the inverse of date.fromisoformat()
.
date.
__str__
()¶
For a date d, str(d)
is equivalent to d.isoformat()
.
date.
ctime
()¶
Return a string representing the date:
>>> from datetime import date
>>> date(2002, 12, 4).ctime()
'Wed Dec 4 00:00:00 2002'
d.ctime()
is equivalent to:
time.ctime(time.mktime(d.timetuple()))
on platforms where the native C
ctime()
function (which time.ctime()
invokes, but which
date.ctime()
does not invoke) conforms to the C standard.
date.
strftime
(format)¶
Return a string representing the date, controlled by an explicit format string. Format codes referring to hours, minutes or seconds will see 0 values. For a complete list of formatting directives, see strftime() and strptime() Behavior.
date.
__format__
(format)¶
Same as date.strftime()
. This makes it possible to specify a format
string for a date
object in formatted string
literals and when using str.format()
. For a
complete list of formatting directives, see
strftime() and strptime() Behavior.
Examples of Usage: date
¶
Example of counting days to an event:
>>> import time
>>> from datetime import date
>>> today = date.today()
>>> today
datetime.date(2007, 12, 5)
>>> today == date.fromtimestamp(time.time())
True
>>> my_birthday = date(today.year, 6, 24)
>>> if my_birthday < today:
... my_birthday = my_birthday.replace(year=today.year + 1)
>>> my_birthday
datetime.date(2008, 6, 24)
>>> time_to_birthday = abs(my_birthday - today)
>>> time_to_birthday.days
202
More examples of working with date
:
>>> from datetime import date
>>> d = 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 to 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¶
A datetime
object is a single object containing all the information
from a date
object and a time
object.
Like a date
object, datetime
assumes the current Gregorian
calendar extended in both directions; like a time
object,
datetime
assumes there are exactly 3600*24 seconds in every day.
Constructor:
class datetime.
datetime
(year, month, day, hour=0, minute=0, second=0, microsecond=0, tzinfo=None, *, fold=0)¶
The year, month and day arguments are required. tzinfo may be None
, or an
instance of a tzinfo
subclass. The remaining arguments must be integers
in the following ranges:
MINYEAR <= year <= MAXYEAR
,1 <= 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]
.
If an argument outside those ranges is given, ValueError
is raised.
New in version 3.6: Added the fold
argument.
Other constructors, all class methods:
classmethod datetime.
today
()¶
Return the current local datetime, with tzinfo
None
.
Equivalent to:
datetime.fromtimestamp(time.time())
See also now()
, fromtimestamp()
.
This method is functionally equivalent to now()
, but without a
tz
parameter.
classmethod datetime.
now
(tz=None)¶
Return the current local date and time.
If optional argument tz is None
or not specified, this is like today()
, but, if possible, supplies more
precision than can be gotten from going through a time.time()
timestamp
(for example, this may be possible on platforms supplying the C
gettimeofday()
function).
If tz is not None
, it must be an instance of a tzinfo
subclass,
and the current date and time are converted to tz’s time zone.
This function is preferred over today()
and utcnow()
.
classmethod datetime.
utcnow
()¶
Return the current UTC date and time, with tzinfo
None
.
This is like now()
, but returns the current UTC date and time, as a naive
datetime
object. An aware current UTC datetime can be obtained by
calling datetime.now(timezone.utc)
. See also now()
.
Warning
Because naive datetime
objects are treated by many datetime
methods
as local times, it is preferred to use aware datetimes to represent times
in UTC. As such, the recommended way to create an object representing the
current time in UTC is by calling datetime.now(timezone.utc)
.
classmethod datetime.
fromtimestamp
(timestamp, tz=None)¶
Return the local date and time corresponding to the POSIX timestamp, such as is
returned by time.time()
. If optional argument tz is None
or not
specified, the timestamp is converted to the platform’s local date and time, and
the returned datetime
object is naive.
If tz is not None
, it must be an instance of a tzinfo
subclass, and the
timestamp is converted to tz’s time zone.
fromtimestamp()
may raise OverflowError
, if the timestamp is out of
the range of values supported by the platform C localtime()
or
gmtime()
functions, and OSError
on localtime()
or
gmtime()
failure.
It’s common for this to be restricted to years in
1970 through 2038. Note that on non-POSIX systems that include leap seconds in
their notion of a timestamp, leap seconds are ignored by fromtimestamp()
,
and then it’s possible to have two timestamps differing by a second that yield
identical datetime
objects. This method is preferred over
utcfromtimestamp()
.
Changed in version 3.3: Raise OverflowError
instead of ValueError
if the timestamp
is out of the range of values supported by the platform C
localtime()
or gmtime()
functions. Raise OSError
instead of ValueError
on localtime()
or gmtime()
failure.
Changed in version 3.6: fromtimestamp()
may return instances with fold
set to 1.
classmethod datetime.
utcfromtimestamp
(timestamp)¶
Return the UTC datetime
corresponding to the POSIX timestamp, with
tzinfo
None
. (The resulting object is naive.)
This may raise OverflowError
, if the timestamp is
out of the range of values supported by the platform C gmtime()
function,
and OSError
on gmtime()
failure.
It’s common for this to be restricted to years in 1970 through 2038.
To get an aware datetime
object, call fromtimestamp()
:
datetime.fromtimestamp(timestamp, timezone.utc)
On the POSIX compliant platforms, it is equivalent to the following expression:
datetime(1970, 1, 1, tzinfo=timezone.utc) + timedelta(seconds=timestamp)
except the latter formula always supports the full years range: between
MINYEAR
and MAXYEAR
inclusive.
Warning
Because naive datetime
objects are treated by many datetime
methods
as local times, it is preferred to use aware datetimes to represent times
in UTC. As such, the recommended way to create an object representing a
specific timestamp in UTC is by calling
datetime.fromtimestamp(timestamp, tz=timezone.utc)
.
Changed in version 3.3: Raise OverflowError
instead of ValueError
if the timestamp
is out of the range of values supported by the platform C
gmtime()
function. Raise OSError
instead of
ValueError
on gmtime()
failure.
classmethod datetime.
fromordinal
(ordinal)¶
Return the datetime
corresponding to the proleptic Gregorian ordinal,
where January 1 of year 1 has ordinal 1. ValueError
is raised unless 1
<= ordinal <= datetime.max.toordinal()
. The hour, minute, second and
microsecond of the result are all 0, and tzinfo
is None
.
classmethod datetime.
combine
(date, time, tzinfo=self.tzinfo)¶
Return a new datetime
object whose date components are equal to the
given date
object’s, and whose time components
are equal to the given time
object’s. If the tzinfo
argument is provided, its value is used to set the tzinfo
attribute
of the result, otherwise the tzinfo
attribute of the time argument
is used.
For any datetime
object d,
d == datetime.combine(d.date(), d.time(), d.tzinfo)
. If date is a
datetime
object, its time components and tzinfo
attributes
are ignored.
Changed in version 3.6: Added the tzinfo argument.
classmethod datetime.
fromisoformat
(date_string)¶
Return a datetime
corresponding to a date_string in one of the
formats emitted by date.isoformat()
and datetime.isoformat()
.
Specifically, this function supports strings in the format:
YYYY-MM-DD[*HH[:MM[:SS[.fff[fff]]]][+HH:MM[:SS[.ffffff]]]]
where *
can match any single character.
Caution
This does not support parsing arbitrary ISO 8601 strings - it is only intended
as the inverse operation of datetime.isoformat()
. A more full-featured
ISO 8601 parser, dateutil.parser.isoparse
is available in the third-party package
dateutil.
Examples:
>>> from datetime import datetime
>>> datetime.fromisoformat('2011-11-04')
datetime.datetime(2011, 11, 4, 0, 0)
>>> datetime.fromisoformat('2011-11-04T00:05:23')
datetime.datetime(2011, 11, 4, 0, 5, 23)
>>> datetime.fromisoformat('2011-11-04 00:05:23.283')
datetime.datetime(2011, 11, 4, 0, 5, 23, 283000)
>>> datetime.fromisoformat('2011-11-04 00:05:23.283+00:00')
datetime.datetime(2011, 11, 4, 0, 5, 23, 283000, tzinfo=datetime.timezone.utc)
>>> datetime.fromisoformat('2011-11-04T00:05:23+04:00')
datetime.datetime(2011, 11, 4, 0, 5, 23,
tzinfo=datetime.timezone(datetime.timedelta(seconds=14400)))
New in version 3.7.
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()
.
New in version 3.8.
classmethod datetime.
strptime
(date_string, format)¶
Return a datetime
corresponding to date_string, parsed according to
format.
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. For a complete list of formatting directives, see
strftime() and strptime() Behavior.
Class attributes:
datetime.
min
¶
The earliest representable datetime
, datetime(MINYEAR, 1, 1,
tzinfo=None)
.
datetime.
max
¶
The latest representable datetime
, datetime(MAXYEAR, 12, 31, 23, 59,
59, 999999, tzinfo=None)
.
datetime.
resolution
¶
The smallest possible difference between non-equal datetime
objects,
timedelta(microseconds=1)
.
Instance attributes (read-only):
datetime.
year
¶
Between MINYEAR
and MAXYEAR
inclusive.
datetime.
month
¶
Between 1 and 12 inclusive.
datetime.
day
¶
Between 1 and the number of days in the given month of the given year.
datetime.
hour
¶
In range(24)
.
datetime.
minute
¶
In range(60)
.
datetime.
second
¶
In range(60)
.
datetime.
microsecond
¶
In range(1000000)
.
datetime.
tzinfo
¶
The object passed as the tzinfo argument to the datetime
constructor,
or None
if none was passed.
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 value 0 (1) represents the earlier (later) of the two moments with the same wall
time representation.
New in version 3.6.
Supported operations:
Operation |
Result |
---|---|
|
|
|
|
|
|
|
datetime2 is a duration of timedelta removed from datetime1, moving forward in time if
timedelta.days
> 0, or backward iftimedelta.days
< 0. The result has the sametzinfo
attribute as the input datetime, and datetime2 - datetime1 == timedelta after.OverflowError
is raised if datetime2.year would be smaller thanMINYEAR
or larger thanMAXYEAR
. Note that no time zone adjustments are done even if the input is an aware object.Computes the datetime2 such that datetime2 + timedelta == datetime1. As for addition, the result has the same
tzinfo
attribute as the input datetime, and no time zone adjustments are done even if the input is aware.Subtraction of a
datetime
from adatetime
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, thetzinfo
attributes are ignored, and the result is atimedelta
object t such thatdatetime2 + t == datetime1
. No time zone adjustments are done in this case.If both are aware and have different
tzinfo
attributes,a-b
acts as if a and b were first converted to naive UTC datetimes first. The result is(a.replace(tzinfo=None) - a.utcoffset()) - (b.replace(tzinfo=None) - b.utcoffset())
except that the implementation never overflows.datetime1 is considered less than datetime2 when datetime1 precedes datetime2 in time.
If one comparand is naive and the other is aware,
TypeError
is raised if an order comparison is attempted. For equality comparisons, naive instances are never equal to aware instances.If both comparands are aware, and have the same
tzinfo
attribute, the commontzinfo
attribute is ignored and the base datetimes are compared. If both comparands are aware and have differenttzinfo
attributes, the comparands are first adjusted by subtracting their UTC offsets (obtained fromself.utcoffset()
).Changed in version 3.3: Equality comparisons between aware and naive
datetime
instances don’t raiseTypeError
.In order to stop comparison from falling back to the default scheme of comparing object addresses, datetime comparison normally raises
TypeError
if the other comparand isn’t also adatetime
object. However,NotImplemented
is returned instead if the other comparand has atimetuple()
attribute. This hook gives other kinds of date objects a chance at implementing mixed-type comparison. If not, when adatetime
object is compared to an object of a different type,TypeError
is raised unless the comparison is==
or!=
. The latter cases returnFalse
orTrue
, respectively.
Instance methods:
datetime.
date
()¶
Return date
object with same year, month and day.
datetime.
time
()¶
Return time
object with same hour, minute, second, microsecond and fold.
tzinfo
is None
. See also method timetz()
.
Changed in version 3.6: The fold value is copied to the returned time
object.
datetime.
timetz
()¶
Return time
object with same hour, minute, second, microsecond, fold, and
tzinfo attributes. See also method time()
.
Changed in version 3.6: The fold value is copied to the returned time
object.
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 datetime with the same attributes, except for those attributes given
new values by whichever keyword arguments are specified. Note that
tzinfo=None
can be specified to create a naive datetime from an aware
datetime with no conversion of date and time data.
New in version 3.6: Added the fold
argument.
datetime.
astimezone
(tz=None)¶
Return a datetime
object with new tzinfo
attribute tz,
adjusting the date and time data so the result is the same UTC time as
self, but in tz’s local time.
If provided, tz must be an instance of a tzinfo
subclass, and its
utcoffset()
and dst()
methods must not return None
. If self
is naive, it is presumed to represent time in the system timezone.
If called without arguments (or with tz=None
) the system local
timezone is assumed for the target timezone. The .tzinfo
attribute of the converted
datetime instance will be set to an instance of timezone
with the zone name and offset obtained from the OS.
If self.tzinfo
is tz, self.astimezone(tz)
is equal to self: no
adjustment of date or time data is performed. Else the result is local
time in the timezone tz, representing the same UTC time as self: after
astz = dt.astimezone(tz)
, astz - astz.utcoffset()
will have
the same date and time data as dt - dt.utcoffset()
.
If you merely want to attach a time zone object tz to a datetime dt without
adjustment of date and time data, use dt.replace(tzinfo=tz)
. If you
merely want to remove the time zone object from an aware datetime dt without
conversion of date and time data, use dt.replace(tzinfo=None)
.
Note that the default tzinfo.fromutc()
method can be overridden in a
tzinfo
subclass to affect the result returned by astimezone()
.
Ignoring error cases, astimezone()
acts like:
def astimezone(self, tz):
if self.tzinfo is tz:
return self
# Convert self to UTC, and attach the new time zone object.
utc = (self - self.utcoffset()).replace(tzinfo=tz)
# Convert from UTC to tz's local time.
return tz.fromutc(utc)
Changed in version 3.3: tz now can be omitted.
Changed in version 3.6: The astimezone()
method can now be called on naive instances that
are presumed to represent system local time.
datetime.
utcoffset
()¶
If tzinfo
is None
, returns None
, else returns
self.tzinfo.utcoffset(self)
, and raises an exception if the latter doesn’t
return None
or a timedelta
object with magnitude less than one day.
Changed in version 3.7: The UTC offset is not restricted to a whole number of minutes.
datetime.
dst
()¶
If tzinfo
is None
, returns None
, else returns
self.tzinfo.dst(self)
, and raises an exception if the latter doesn’t return
None
or a timedelta
object with magnitude less than one day.
Changed in version 3.7: The DST offset is not restricted to a whole number of minutes.
datetime.
tzname
()¶
If tzinfo
is None
, returns None
, else returns
self.tzinfo.tzname(self)
, raises an exception if the latter doesn’t return
None
or a string object,
datetime.
timetuple
()¶
Return a time.struct_time
such as returned by time.localtime()
.
d.timetuple()
is equivalent to:
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.
Warning
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 utcfromtimetuple
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
()¶
Return the proleptic Gregorian ordinal of the date. The same as
self.date().toordinal()
.
datetime.
timestamp
()¶
Return POSIX timestamp corresponding to the datetime
instance. The return value is a float
similar to that
returned by time.time()
.
Naive datetime
instances are assumed to represent local
time and this method relies on the platform C mktime()
function to perform the conversion. Since datetime
supports wider range of values than mktime()
on many
platforms, this method may raise OverflowError
for times far
in the past or far in the future.
For aware datetime
instances, the return value is computed
as:
(dt - datetime(1970, 1, 1, tzinfo=timezone.utc)).total_seconds()
New in version 3.3.
Changed in version 3.6: The timestamp()
method uses the fold
attribute to
disambiguate the times during a repeated interval.
There is no method to obtain the POSIX timestamp directly from a
naive datetime
instance representing UTC time. If your
application uses this convention and your system timezone is not
set to UTC, you can obtain the POSIX timestamp by supplying
tzinfo=timezone.utc
:
timestamp = dt.replace(tzinfo=timezone.utc).timestamp()
or by calculating the timestamp directly:
timestamp = (dt - datetime(1970, 1, 1)) / timedelta(seconds=1)
datetime.
weekday
()¶
Return the day of the week as an integer, where Monday is 0 and Sunday is 6.
The same as self.date().weekday()
. See also isoweekday()
.
datetime.
isoweekday
()¶
Return the day of the week as an integer, where Monday is 1 and Sunday is 7.
The same as self.date().isoweekday()
. See also weekday()
,
isocalendar()
.
datetime.
isocalendar
()¶
Return a named tuple with three components: year
, week
and weekday
. The same as self.date().isocalendar()
.
datetime.
isoformat
(sep='T', timespec='auto')¶
Return a string representing the date and time in ISO 8601 format:
YYYY-MM-DDTHH:MM:SS.ffffff
, ifmicrosecond
is not 0YYYY-MM-DDTHH:MM:SS
, ifmicrosecond
is 0
If utcoffset()
does not return None
, a string is
appended, giving the UTC offset:
YYYY-MM-DDTHH:MM:SS.ffffff+HH:MM[:SS[.ffffff]]
, ifmicrosecond
is not 0YYYY-MM-DDTHH:MM:SS+HH:MM[:SS[.ffffff]]
, ifmicrosecond
is 0
Examples:
>>> from datetime import datetime, timezone
>>> datetime(2019, 5, 18, 15, 17, 8, 132263).isoformat()
'2019-05-18T15:17:08.132263'
>>> datetime(2019, 5, 18, 15, 17, tzinfo=timezone.utc).isoformat()
'2019-05-18T15:17:00+00:00'
The optional argument sep (default 'T'
) is a one-character separator,
placed between the date and time portions of the result. For example:
>>> from datetime import tzinfo, timedelta, datetime
>>> class TZ(tzinfo):
... """A time zone with an arbitrary, constant -06:39 offset."""
... def utcoffset(self, dt):
... return timedelta(hours=-6, minutes=-39)
...
>>> datetime(2002, 12, 25, tzinfo=TZ()).isoformat(' ')
'2002-12-25 00:00:00-06:39'
>>> datetime(2009, 11, 27, microsecond=100, tzinfo=TZ()).isoformat()
'2009-11-27T00:00:00.000100-06:39'
The optional argument timespec specifies the number of additional
components of the time to include (the default is 'auto'
).
It can be one of the following:
'auto'
: Same as'seconds'
ifmicrosecond
is 0, same as'microseconds'
otherwise.'hours'
: Include thehour
in the two-digitHH
format.'seconds'
: Includehour
,minute
, andsecond
inHH:MM:SS
format.'milliseconds'
: Include full time, but truncate fractional second part to milliseconds.HH:MM:SS.sss
format.'microseconds'
: Include full time inHH:MM:SS.ffffff
format.
Excluded time components are truncated, not rounded.
ValueError
will be raised on an invalid timespec argument:
>>> from datetime import datetime
>>> datetime.now().isoformat(timespec='minutes')
'2002-12-25T00:00'
>>> dt = datetime(2015, 1, 1, 12, 30, 59, 0)
>>> dt.isoformat(timespec='microseconds')
'2015-01-01T12:30:59.000000'
New in version 3.6: Added the timespec argument.
datetime.
__str__
()¶
For a datetime
instance d, str(d)
is equivalent to
d.isoformat(' ')
.
datetime.
ctime
()¶
Return a string representing the date and time:
>>> from datetime import datetime
>>> datetime(2002, 12, 4, 20, 30, 40).ctime()
'Wed Dec 4 20:30:40 2002'
The output string will not include time zone information, regardless of whether the input is aware or naive.
d.ctime()
is equivalent to:
time.ctime(time.mktime(d.timetuple()))
on platforms where the native C ctime()
function
(which time.ctime()
invokes, but which
datetime.ctime()
does not invoke) conforms to the C standard.
datetime.
strftime
(format)¶
Return a string representing the date and time, controlled by an explicit format string. For a complete list of formatting directives, see strftime() and strptime() Behavior.
datetime.
__format__
(format)¶
Same as datetime.strftime()
. This makes it possible to specify a format
string for a datetime
object in formatted string
literals and when using str.format()
. For a
complete list of formatting directives, see
strftime() and strptime() Behavior.
Examples of Usage: datetime
¶
Examples of working with datetime
objects:
>>> from datetime import datetime, date, time, timezone
>>> # Using datetime.combine()
>>> d = date(2005, 7, 14)
>>> t = time(12, 30)
>>> datetime.combine(d, t)
datetime.datetime(2005, 7, 14, 12, 30)
>>> # Using datetime.now()
>>> datetime.now()
datetime.datetime(2007, 12, 6, 16, 29, 43, 79043) # GMT +1
>>> datetime.now(timezone.utc)
datetime.datetime(2007, 12, 6, 15, 29, 43, 79060, tzinfo=datetime.timezone.utc)
>>> # Using datetime.strptime()
>>> dt = datetime.strptime("21/11/06 16:30", "%d/%m/%y %H:%M")
>>> dt
datetime.datetime(2006, 11, 21, 16, 30)
>>> # Using datetime.timetuple() to get tuple of all attributes
>>> tt = dt.timetuple()
>>> for it in tt:
... print(it)
...
2006 # year
11 # month
21 # day
16 # hour
30 # minute
0 # second
1 # weekday (0 = Monday)
325 # number of days since 1st January
-1 # dst - method tzinfo.dst() returned None
>>> # Date in ISO format
>>> ic = dt.isocalendar()
>>> for it in ic:
... print(it)
...
2006 # ISO year
47 # ISO week
2 # ISO weekday
>>> # Formatting a datetime
>>> dt.strftime("%A, %d. %B %Y %I:%M%p")
'Tuesday, 21. November 2006 04:30PM'
>>> 'The {1} is {0:%d}, the {2} is {0:%B}, the {3} is {0:%I:%M%p}.'.format(dt, "day", "month", "time")
'The day is 21, the month is November, the time is 04:30PM.'
The example below defines a tzinfo
subclass capturing time zone
information for Kabul, Afghanistan, which used +4 UTC until 1945
and then +4:30 UTC thereafter:
from datetime import timedelta, datetime, tzinfo, timezone
class KabulTz(tzinfo):
# Kabul used +4 until 1945, when they moved to +4:30
UTC_MOVE_DATE = datetime(1944, 12, 31, 20, tzinfo=timezone.utc)
def utcoffset(self, dt):
if dt.year < 1945:
return timedelta(hours=4)
elif (1945, 1, 1, 0, 0) <= dt.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 dt falls in the imaginary range, use fold to decide how
# to resolve. See PEP495.
return timedelta(hours=4, minutes=(30 if dt.fold else 0))
else:
return timedelta(hours=4, minutes=30)
def fromutc(self, dt):
# Follow same validations as in datetime.tzinfo
if not isinstance(dt, datetime):
raise TypeError("fromutc() requires a datetime argument")
if dt.tzinfo is not self:
raise ValueError("dt.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 dt.replace(tzinfo=timezone.utc) >= self.UTC_MOVE_DATE:
return dt + timedelta(hours=4, minutes=30)
else:
return dt + timedelta(hours=4)
def dst(self, dt):
# Kabul does not observe daylight saving time.
return timedelta(0)
def tzname(self, dt):
if dt >= self.UTC_MOVE_DATE:
return "+04:30"
return "+04"
Usage of KabulTz
from above:
>>> tz1 = KabulTz()
>>> # Datetime before the change
>>> dt1 = datetime(1900, 11, 21, 16, 30, tzinfo=tz1)
>>> print(dt1.utcoffset())
4:00:00
>>> # Datetime after the change
>>> dt2 = datetime(2006, 6, 14, 13, 0, tzinfo=tz1)
>>> print(dt2.utcoffset())
4:30:00
>>> # Convert datetime to another time zone
>>> dt3 = dt2.astimezone(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)¶
All arguments are optional. tzinfo may be None
, or an instance of a
tzinfo
subclass. The remaining arguments must be integers in the
following ranges:
0 <= 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
.
Class attributes:
time.
min
¶
The earliest representable time
, time(0, 0, 0, 0)
.
time.
max
¶
The latest representable time
, time(23, 59, 59, 999999)
.
time.
resolution
¶
The smallest possible difference between non-equal time
objects,
timedelta(microseconds=1)
, although note that arithmetic on
time
objects is not supported.
Instance attributes (read-only):
time.
hour
¶
In range(24)
.
time.
minute
¶
In range(60)
.
time.
second
¶
In range(60)
.
time.
microsecond
¶
In range(1000000)
.
time.
tzinfo
¶
The object passed as the tzinfo argument to the time
constructor, or
None
if none was passed.
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 value 0 (1) represents the earlier (later) of the two moments with the same wall
time representation.
New in version 3.6.
time
objects support comparison of time
to time
,
where a is considered less
than b when a precedes b in time. If one comparand is naive and the other
is aware, TypeError
is raised if an order comparison is attempted. For equality
comparisons, naive instances are never equal to aware instances.
If both comparands are aware, and have
the same tzinfo
attribute, the common tzinfo
attribute is
ignored and the base times are compared. If both comparands are aware and
have different tzinfo
attributes, the comparands are first adjusted by
subtracting their UTC offsets (obtained from self.utcoffset()
). In order
to stop mixed-type comparisons from falling back to the default comparison by
object address, when a time
object is compared to an object of a
different type, TypeError
is raised unless the comparison is ==
or
!=
. The latter cases return False
or True
, respectively.
Changed in version 3.3: Equality comparisons between aware and naive time
instances
don’t raise TypeError
.
In Boolean contexts, a time
object is always considered to be true.
Changed in version 3.5: Before Python 3.5, a time
object was considered to be false if it
represented midnight in UTC. This behavior was considered obscure and
error-prone and has been removed in Python 3.5. See bpo-13936 for full
details.
Other constructor:
classmethod time.
fromisoformat
(time_string)¶
Return a time
corresponding to a time_string in one of the
formats emitted by time.isoformat()
. Specifically, this function supports
strings in the format:
HH[:MM[:SS[.fff[fff]]]][+HH:MM[:SS[.ffffff]]]
Caution
This does not support parsing arbitrary ISO 8601 strings. It is only
intended as the inverse operation of time.isoformat()
.
Examples:
>>> from datetime import time
>>> time.fromisoformat('04:23:01')
datetime.time(4, 23, 1)
>>> time.fromisoformat('04:23:01.000384')
datetime.time(4, 23, 1, 384)
>>> time.fromisoformat('04:23:01+04:00')
datetime.time(4, 23, 1, tzinfo=datetime.timezone(datetime.timedelta(seconds=14400)))
New in version 3.7.
Instance methods:
time.
replace
(hour=self.hour, minute=self.minute, second=self.second, microsecond=self.microsecond, tzinfo=self.tzinfo, *, fold=0)¶
Return a time
with the same value, except for those attributes given
new values by whichever keyword arguments are specified. Note that
tzinfo=None
can be specified to create a naive time
from an
aware time
, without conversion of the time data.
New in version 3.6: Added the fold
argument.
time.
isoformat
(timespec='auto')¶
Return a string representing the time in ISO 8601 format, one of:
HH:MM:SS.ffffff
, ifmicrosecond
is not 0HH:MM:SS
, ifmicrosecond
is 0HH:MM:SS.ffffff+HH:MM[:SS[.ffffff]]
, ifutcoffset()
does not returnNone
HH:MM:SS+HH:MM[:SS[.ffffff]]
, ifmicrosecond
is 0 andutcoffset()
does not returnNone
The optional argument timespec specifies the number of additional
components of the time to include (the default is 'auto'
).
It can be one of the following:
'auto'
: Same as'seconds'
ifmicrosecond
is 0, same as'microseconds'
otherwise.'hours'
: Include thehour
in the two-digitHH
format.'seconds'
: Includehour
,minute
, andsecond
inHH:MM:SS
format.'milliseconds'
: Include full time, but truncate fractional second part to milliseconds.HH:MM:SS.sss
format.'microseconds'
: Include full time inHH:MM:SS.ffffff
format.
Excluded time components are truncated, not rounded.
ValueError
will be raised on an invalid timespec argument.
Example:
>>> from datetime import time
>>> time(hour=12, minute=34, second=56, microsecond=123456).isoformat(timespec='minutes')
'12:34'
>>> dt = time(hour=12, minute=34, second=56, microsecond=0)
>>> dt.isoformat(timespec='microseconds')
'12:34:56.000000'
>>> dt.isoformat(timespec='auto')
'12:34:56'
New in version 3.6: Added the timespec argument.
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. For a complete list of formatting directives, see strftime() and strptime() Behavior.
time.
__format__
(format)¶
Same as time.strftime()
. This makes it possible to specify a format string
for a time
object in formatted string
literals and when using str.format()
. For a
complete list of formatting directives, see
strftime() and strptime() Behavior.
time.
utcoffset
()¶
If tzinfo
is None
, returns None
, else returns
self.tzinfo.utcoffset(None)
, and raises an exception if the latter doesn’t
return None
or a timedelta
object with magnitude less than one day.
Changed in version 3.7: The UTC offset is not restricted to a whole number of minutes.
time.
dst
()¶
If tzinfo
is None
, returns None
, else returns
self.tzinfo.dst(None)
, and raises an exception if the latter doesn’t return
None
, or a timedelta
object with magnitude less than one day.
Changed in version 3.7: The DST offset is not restricted to a whole number of minutes.
time.
tzname
()¶
If tzinfo
is None
, returns None
, else returns
self.tzinfo.tzname(None)
, or raises an exception if the latter doesn’t
return None
or a string object.
Examples of Usage: time
¶
Examples of working with a time
object:
>>> from datetime import time, tzinfo, timedelta
>>> class TZ1(tzinfo):
... def utcoffset(self, dt):
... return timedelta(hours=1)
... def dst(self, dt):
... return timedelta(0)
... def tzname(self,dt):
... return "+01:00"
... def __repr__(self):
... return f"{self.__class__.__name__}()"
...
>>> t = 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 timezones with fixed offset from UTC such as UTC itself or North
American EST and EDT.
Special requirement for pickling: A tzinfo
subclass must have an
__init__()
method that can be called with no arguments, otherwise it can be
pickled but possibly not unpickled again. This is a technical requirement that
may be relaxed in the future.
A concrete subclass of tzinfo
may need to implement the following
methods. Exactly which methods are needed depends on the uses made of aware
datetime
objects. If in doubt, simply implement all of them.
tzinfo.
utcoffset
(dt)¶
Return offset of local time from UTC, as a timedelta
object that is
positive east of UTC. If local time is west of UTC, this should be negative.
This represents the total offset from UTC; for example, if a
tzinfo
object represents both time zone and DST adjustments,
utcoffset()
should return their sum. If the UTC offset isn’t known,
return None
. Else the value returned must be a timedelta
object
strictly between -timedelta(hours=24)
and timedelta(hours=24)
(the magnitude of the offset must be less than one day). Most implementations
of utcoffset()
will probably look like one of these two:
return CONSTANT # fixed-offset class
return CONSTANT + self.dst(dt) # daylight-aware class
If utcoffset()
does not return None
, dst()
should not return
None
either.
The default implementation of utcoffset()
raises
NotImplementedError
.
Changed in version 3.7: The UTC offset is not restricted to a whole number of minutes.
tzinfo.
dst
(dt)¶
Return the daylight saving time (DST) adjustment, as a timedelta
object or
None
if DST information isn’t known.
Return timedelta(0)
if DST is not in effect.
If DST is in effect, return the offset as a timedelta
object
(see utcoffset()
for details). Note that DST offset, if applicable, has
already been added to the UTC offset returned by utcoffset()
, so there’s
no need to consult dst()
unless you’re interested in obtaining DST info
separately. For example, datetime.timetuple()
calls its tzinfo
attribute’s dst()
method to determine how the tm_isdst
flag
should be set, and tzinfo.fromutc()
calls dst()
to account for
DST changes when crossing time zones.
An instance tz of a tzinfo
subclass that models both standard and
daylight times must be consistent in this sense:
tz.utcoffset(dt) - tz.dst(dt)
must return the same result for every datetime
dt with dt.tzinfo ==
tz
For sane tzinfo
subclasses, this expression yields the time
zone’s “standard offset”, which should not depend on the date or the time, but
only on geographic location. The implementation of datetime.astimezone()
relies on this, but cannot detect violations; it’s the programmer’s
responsibility to ensure it. If a tzinfo
subclass cannot guarantee
this, it may be able to override the default implementation of
tzinfo.fromutc()
to work correctly with astimezone()
regardless.
Most implementations of dst()
will probably look like one of these two:
def dst(self, dt):
# a fixed-offset class: doesn't account for DST
return timedelta(0)
def dst(self, dt):
# Code to set dston and dstoff to the time zone's DST
# transition times based on the input dt.year, and expressed
# in standard local time.
if dston <= dt.replace(tzinfo=None) < dstoff:
return timedelta(hours=1)
else:
return timedelta(0)
The default implementation of dst()
raises NotImplementedError
.
Changed in version 3.7: The DST offset is not restricted to a whole number of minutes.
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.
The default implementation of tzname()
raises NotImplementedError
.
These methods are called by a datetime
or time
object, in
response to their methods of the same names. A datetime
object passes
itself as the argument, and a time
object passes None
as the
argument. A tzinfo
subclass’s methods should therefore be prepared to
accept a dt argument of None
, or of class datetime
.
When None
is passed, it’s up to the class designer to decide the best
response. For example, returning None
is appropriate if the class wishes to
say that time objects don’t participate in the tzinfo
protocols. It
may be more useful for utcoffset(None)
to return the standard UTC offset, as
there is no other convention for discovering the standard offset.
When a datetime
object is passed in response to a datetime
method, dt.tzinfo
is the same object as self. tzinfo
methods can
rely on this, unless user code calls tzinfo
methods directly. The
intent is that the tzinfo
methods interpret dt as being in local
time, and not need worry about objects in other timezones.
There is one more tzinfo
method that a subclass may wish to override:
tzinfo.
fromutc
(dt)¶
This is called from the default datetime.astimezone()
implementation. When called from that, dt.tzinfo
is self, and dt’s
date and time data are to be viewed as expressing a UTC time. The purpose
of fromutc()
is to adjust the date and time data, returning an
equivalent datetime in self’s local time.
Most tzinfo
subclasses should be able to inherit the default
fromutc()
implementation without problems. It’s strong enough to handle
fixed-offset time zones, and time zones accounting for both standard and
daylight time, and the latter even if the DST transition times differ in
different years. An example of a time zone the default fromutc()
implementation may not handle correctly in all cases is one where the standard
offset (from UTC) depends on the specific date and time passed, which can happen
for political reasons. The default implementations of astimezone()
and
fromutc()
may not produce the result you want if the result is one of the
hours straddling the moment the standard offset changes.
Skipping code for error cases, the default fromutc()
implementation acts
like:
def fromutc(self, dt):
# raise ValueError error if dt.tzinfo is not self
dtoff = dt.utcoffset()
dtdst = dt.dst()
# raise ValueError if dtoff is None or dtdst is None
delta = dtoff - dtdst # this is self's standard offset
if delta:
dt += delta # convert to standard local time
dtdst = dt.dst()
# raise ValueError if dtdst is None
if dtdst:
return dt + dtdst
else:
return dt
In the following tzinfo_examples.py
file there are some examples of
tzinfo
classes:
from datetime import tzinfo, timedelta, datetime
ZERO = timedelta(0)
HOUR = timedelta(hours=1)
SECOND = timedelta(seconds=1)
# 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 as _time
STDOFFSET = timedelta(seconds = -_time.timezone)
if _time.daylight:
DSTOFFSET = timedelta(seconds = -_time.altzone)
else:
DSTOFFSET = STDOFFSET
DSTDIFF = DSTOFFSET - STDOFFSET
class LocalTimezone(tzinfo):
def fromutc(self, dt):
assert dt.tzinfo is self
stamp = (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 datetime(*args, microsecond=dt.microsecond,
tzinfo=self, fold=fold)
def utcoffset(self, dt):
if self._isdst(dt):
return DSTOFFSET
else:
return STDOFFSET
def dst(self, dt):
if self._isdst(dt):
return DSTDIFF
else:
return ZERO
def tzname(self, dt):
return _time.tzname[self._isdst(dt)]
def _isdst(self, dt):
tt = (dt.year, dt.month, dt.day,
dt.hour, dt.minute, dt.second,
dt.weekday(), 0, 0)
stamp = _time.mktime(tt)
tt = _time.localtime(stamp)
return tt.tm_isdst > 0
Local = LocalTimezone()
# A complete implementation of current DST rules for major US time zones.
def first_sunday_on_or_after(dt):
days_to_go = 6 - dt.weekday()
if days_to_go:
dt += timedelta(days_to_go)
return dt
# US DST Rules
#
# This is a simplified (i.e., wrong for a few cases) set of rules for US
# DST start and end times. For a complete and up-to-date set of DST rules
# and timezone definitions, visit the Olson Database (or try pytz):
# http://www.twinsun.com/tz/tz-link.htm
# http://sourceforge.net/projects/pytz/ (might not be up-to-date)
#
# In the US, since 2007, DST starts at 2am (standard time) on the second
# Sunday in March, which is the first Sunday on or after Mar 8.
DSTSTART_2007 = datetime(1, 3, 8, 2)
# and ends at 2am (DST time) on the first Sunday of Nov.
DSTEND_2007 = 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 = datetime(1, 4, 1, 2)
DSTEND_1987_2006 = 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 = 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 (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(tzinfo):
def __init__(self, hours, reprname, stdname, dstname):
self.stdoffset = timedelta(hours=hours)
self.reprname = reprname
self.stdname = stdname
self.dstname = dstname
def __repr__(self):
return self.reprname
def tzname(self, dt):
if self.dst(dt):
return self.dstname
else:
return self.stdname
def utcoffset(self, dt):
return self.stdoffset + self.dst(dt)
def dst(self, dt):
if dt is None or dt.tzinfo is None:
# An exception may be sensible here, in one or both cases.
# It depends on how you want to treat them. The default
# fromutc() implementation (called by the default astimezone()
# implementation) passes a datetime with dt.tzinfo is self.
return ZERO
assert dt.tzinfo is self
start, end = us_dst_range(dt.year)
# Can't compare naive to aware objects, so strip the timezone from
# dt first.
dt = dt.replace(tzinfo=None)
if start + HOUR <= dt < end - HOUR:
# DST is in effect.
return HOUR
if end - HOUR <= dt < end:
# Fold (an ambiguous hour): use dt.fold to disambiguate.
return ZERO if dt.fold else HOUR
if start <= dt < start + HOUR:
# Gap (a non-existent hour): reverse the fold rule.
return HOUR if dt.fold else ZERO
# DST is off.
return ZERO
def fromutc(self, dt):
assert dt.tzinfo is self
start, end = us_dst_range(dt.year)
start = start.replace(tzinfo=self)
end = end.replace(tzinfo=self)
std_time = dt + 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")
Note that there are unavoidable subtleties twice per year in a tzinfo
subclass accounting for both standard and daylight time, at the DST transition
points. For concreteness, consider US Eastern (UTC -0500), where EDT begins the
minute after 1:59 (EST) on the second Sunday in March, and ends the minute after
1:59 (EDT) on the first Sunday in November:
UTC 3:MM 4:MM 5:MM 6:MM 7:MM 8:MM
EST 22:MM 23:MM 0:MM 1:MM 2:MM 3:MM
EDT 23:MM 0:MM 1:MM 2:MM 3:MM 4:MM
start 22:MM 23:MM 0:MM 1:MM 3:MM 4:MM
end 23:MM 0:MM 1:MM 1:MM 2:MM 3:MM
When DST starts (the “start” line), the local wall clock leaps from 1:59 to
3:00. A wall time of the form 2:MM doesn’t really make sense on that day, so
astimezone(Eastern)
won’t deliver a result with hour == 2
on the day DST
begins. For example, at the Spring forward transition of 2016, we get:
>>> from datetime import datetime, timezone
>>> from tzinfo_examples import HOUR, Eastern
>>> u0 = datetime(2016, 3, 13, 5, tzinfo=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:
>>> u0 = datetime(2016, 11, 6, 4, tzinfo=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)).
See also
IANA timezone databasezoneinfo
The
datetime
module has a basictimezone
class (for handling arbitrary fixed offsets from UTC) and itstimezone.utc
attribute (a UTC timezone instance).
zoneinfo
brings the IANA timezone database (also known as the Olson database) to Python, and its usage is recommended.
The Time Zone Database (often called tz, tzdata or zoneinfo) contains code and data that represent the history of local time for many representative locations around the globe. It is updated periodically to reflect changes made by political bodies to time zone boundaries, UTC offsets, and daylight-saving rules.
timezone
Objects¶
The timezone
class is a subclass of tzinfo
, each
instance of which represents a timezone defined by a fixed offset from
UTC.
Objects of this class cannot be used to represent timezone information in the locations where different offsets are used in different days of the year or where historical changes have been made to civil time.
class datetime.
timezone
(offset, name=None)¶
The offset argument must be specified as a timedelta
object representing the difference between the local time and UTC. It must
be strictly between -timedelta(hours=24)
and
timedelta(hours=24)
, otherwise ValueError
is raised.
The name argument is optional. If specified it must be a string that
will be used as the value returned by the datetime.tzname()
method.
New in version 3.2.
Changed in version 3.7: The UTC offset is not restricted to a whole number of minutes.
timezone.
utcoffset
(dt)¶
Return the fixed value specified when the timezone
instance is
constructed.
The dt argument is ignored. The return value is a timedelta
instance equal to the difference between the local time and UTC.
Changed in version 3.7: The UTC offset is not restricted to a whole number of minutes.
timezone.
tzname
(dt)¶
Return the fixed value specified when the timezone
instance
is constructed.
If name is not provided in the constructor, the name returned by
tzname(dt)
is generated from the value of the offset
as follows. If
offset is timedelta(0)
, the name is “UTC”, otherwise it is a string in
the format UTC±HH:MM
, where ± is the sign of offset
, HH and MM are
two digits of offset.hours
and offset.minutes
respectively.
Changed in version 3.6: Name generated from offset=timedelta(0)
is now plain ‘UTC’, not
'UTC+00:00'
.
timezone.
dst
(dt)¶
Always returns None
.
timezone.
fromutc
(dt)¶
Return dt + offset
. The dt argument must be an aware
datetime
instance, with tzinfo
set to self
.
Class attributes:
timezone.
utc
¶
The UTC timezone, timezone(timedelta(0))
.
strftime()
and strptime()
Behavior¶
date
, datetime
, and time
objects all support a
strftime(format)
method, to create a string representing the time under the
control of an explicit format string.
Conversely, the datetime.strptime()
class method creates a
datetime
object from a string representing a date and time and a
corresponding format string.
The table below provides a high-level comparison of strftime()
versus strptime()
:
|
|
|
---|---|---|
Usage |
Convert object to a string according to a given format |
Parse a string into a |
Type of method |
Instance method |
Class method |
Method of |
||
Signature |
|
|
strftime()
and strptime()
Format Codes¶
The following is a list of all the format codes that the 1989 C standard requires, and these work on all platforms with a standard C implementation.
Directive |
Meaning |
Example |
Notes |
---|---|---|---|
|
Weekday as locale’s abbreviated name. |
Sun, Mon, …, Sat
(en_US);
So, Mo, …, Sa
(de_DE)
|
|
|
Weekday as locale’s full name. |
Sunday, Monday, …,
Saturday (en_US);
Sonntag, Montag, …,
Samstag (de_DE)
|
|
|
Weekday as a decimal number, where 0 is Sunday and 6 is Saturday. |
0, 1, …, 6 |
|
|
Day of the month as a zero-padded decimal number. |
01, 02, …, 31 |
|
|
Month as locale’s abbreviated name. |
Jan, Feb, …, Dec
(en_US);
Jan, Feb, …, Dez
(de_DE)
|
|
|
Month as locale’s full name. |
January, February,
…, December (en_US);
Januar, Februar, …,
Dezember (de_DE)
|
|
|
Month as a zero-padded decimal number. |
01, 02, …, 12 |
|
|
Year without century as a zero-padded decimal number. |
00, 01, …, 99 |
|
|
Year with century as a decimal number. |
0001, 0002, …, 2013, 2014, …, 9998, 9999 |
|
|
Hour (24-hour clock) as a zero-padded decimal number. |
00, 01, …, 23 |
|
|
Hour (12-hour clock) as a zero-padded decimal number. |
01, 02, …, 12 |
|
|
Locale’s equivalent of either AM or PM. |
AM, PM (en_US);
am, pm (de_DE)
|
(1), (3) |
|
Minute as a zero-padded decimal number. |
00, 01, …, 59 |
|
|
Second as a zero-padded decimal number. |
00, 01, …, 59 |
(4), (9) |
|
Microsecond as a decimal number, zero-padded to 6 digits. |
000000, 000001, …, 999999 |
|
|
UTC offset in the form
|
(empty), +0000, -0400, +1030, +063415, -030712.345216 |
|
|
Time zone name (empty string if the object is naive). |
(empty), UTC, GMT |
|
|
Day of the year as a zero-padded decimal number. |
001, 002, …, 366 |
|
|
Week number of the year (Sunday as the first day of the week) as a zero-padded decimal number. All days in a new year preceding the first Sunday are considered to be in week 0. |
00, 01, …, 53 |
(7), (9) |
|
Week number of the year (Monday as the first day of the week) as a zero-padded decimal number. All days in a new year preceding the first Monday are considered to be in week 0. |
00, 01, …, 53 |
(7), (9) |
|
Locale’s appropriate date and time representation. |
Tue Aug 16 21:30:00
1988 (en_US);
Di 16 Aug 21:30:00
1988 (de_DE)
|
|
|
Locale’s appropriate date representation. |
08/16/88 (None);
08/16/1988 (en_US);
16.08.1988 (de_DE)
|
|
|
Locale’s appropriate time representation. |
21:30:00 (en_US);
21:30:00 (de_DE)
|
|
|
A literal |
Several additional directives not required by the C89 standard are included for convenience. These parameters all correspond to ISO 8601 date values.
Directive |
Meaning |
Example |
Notes |
---|---|---|---|
|
ISO 8601 year with century
representing the year that
contains the greater part of
the ISO week ( |
0001, 0002, …, 2013, 2014, …, 9998, 9999 |
|
|
ISO 8601 weekday as a decimal number where 1 is Monday. |
1, 2, …, 7 |
|
|
ISO 8601 week as a decimal number with Monday as the first day of the week. Week 01 is the week containing Jan 4. |
01, 02, …, 53 |
(8), (9) |
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.
New in version 3.6: %G
, %u
and %V
were 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()
class method, 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. 4
Using datetime.strptime(date_string, format)
is equivalent to:
datetime(*(time.strptime(date_string, format)[0:6]))
except when the format includes sub-second components or timezone 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.
For the same reason, handling of format strings containing Unicode code points
that can’t be represented in the charset of the current locale is also
platform-dependent. On some platforms such code points are preserved intact in
the output, while on others strftime
may raise UnicodeError
or return
an empty string instead.
Notes:
Because the format depends on the current locale, care should be taken when making assumptions about the output value. Field orderings will vary (for example, “month/day/year” versus “day/month/year”), and the output may contain Unicode characters encoded using the locale’s default encoding (for example, if the current locale is
ja_JP
, the default encoding could be any one ofeucJP
,SJIS
, orutf-8
; uselocale.getlocale()
to determine the current locale’s encoding).The
strptime()
method can parse years in the full [1, 9999] range, but years < 1000 must be zero-filled to 4-digit width.Changed in version 3.2: In previous versions,
strftime()
method was restricted to years >= 1900.Changed in version 3.3: In version 3.2,
strftime()
method was restricted to years >= 1000.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.Unlike the
time
module, thedatetime
module does not support leap seconds.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).For a naive object, the
%z
and%Z
format codes are replaced by empty strings.For an aware object:
%z
utcoffset()
is transformed into a string of the form±HHMM[SS[.ffffff]]
, whereHH
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 andffffff
is a 6-digit string giving the number of UTC offset microseconds. Theffffff
part is omitted when the offset is a whole number of seconds and both theffffff
and theSS
part is omitted when the offset is a whole number of minutes. For example, ifutcoffset()
returnstimedelta(hours=-3, minutes=-30)
,%z
is replaced with the string'-0330'
.Changed in version 3.7: The UTC offset is not restricted to a whole number of minutes.
Changed in version 3.7: When the
%z
directive is provided to thestrptime()
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
In
strftime()
,%Z
is replaced by an empty string iftzname()
returnsNone
; otherwise%Z
is replaced by the returned value, which must be a string.strptime()
only accepts certain values for%Z
:any value in
time.tzname
for your machine’s localethe hard-coded values
UTC
andGMT
So someone living in Japan may have
JST
,UTC
, andGMT
as valid values, but probably notEST
. It will raiseValueError
for invalid values.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.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 astrptime()
format string. Also note that%G
and%Y
are not interchangeable.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.
Footnotes
If, that is, we ignore the effects of Relativity
This matches the definition of the “proleptic Gregorian” calendar in Dershowitz and Reingold’s book Calendrical Calculations, where it’s the base calendar for all computations. See the book for algorithms for converting between proleptic Gregorian ordinals and many other calendar systems.
See R. H. van Gent’s guide to the mathematics of the ISO 8601 calendar for a good explanation.
Passing datetime.strptime('Feb 29', '%b %d')
will fail since 1900
is not a leap year.
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