python-dateutil

Contents

Description
News
Features
Quick example
Source code and development
Download
Author
Documentation

Description

The dateutil module provides powerful extensions to the standard datetime module, available in Python 2.3+.

News

2011-03-24
- dateutil 2.0 is out!
- Ported to Python 3, by Brian Jones. If you need dateutil for Python 2.X, please continue using the 1.X series.
- There's no such thing as a "PSF License". This source code is now made available under the Simplified BSD license. See LICENSE for details.

Features

Computing of relative deltas (next month, next year, next monday, last week of month, etc);
Computing of relative deltas between two given date and/or datetime objects;
Computing of dates based on very flexible recurrence rules, using a superset of the
iCalendar specification. Parsing of RFC strings is supported as well.
Generic parsing of dates in almost any string format;
Timezone (tzinfo) implementations for tzfile(5) format files (/etc/localtime, /usr/share/zoneinfo, etc), TZ environment string (in all known formats), iCalendar format files, given ranges (with help from relative deltas), local machine timezone, fixed offset timezone, UTC timezone, and Windows registry-based time zones.
Internal up-to-date world timezone information based on Olson's database.
Computing of Easter Sunday dates for any given year, using Western, Orthodox or Julian algorithms;
More than 400 test cases.

Quick example

Here's a snapshot, just to give an idea about the power of the package. For more examples, look at the documentation below.

Suppose you want to know how much time is left, in years/months/days/etc, before the next easter happening on a year with a Friday 13th in August, and you want to get today's date out of the "date" unix system command. Here is the code:

from dateutil.relativedelta import *
from dateutil.easter import *
from dateutil.rrule import *
from dateutil.parser import *
from datetime import *
import commands
import os
now = parse(commands.getoutput("date"))
today = now.date()
year = rrule(YEARLY,bymonth=8,bymonthday=13,byweekday=FR)[0].year
rdelta = relativedelta(easter(year), today)
print "Today is:", today
print "Year with next Aug 13th on a Friday is:", year
print "How far is the Easter of that year:", rdelta
print "And the Easter of that year is:", today+rdelta

And here's the output:

Today is: 2003-10-11
Year with next Aug 13th on a Friday is: 2004
How far is the Easter of that year: relativedelta(months=+6)
And the Easter of that year is: 2004-04-11

Being exactly 6 months ahead was really a coincidence

Source code and development

Development is currently maintained in Launchpad:

https://launchpad.net/dateutil

Download

The following files are available.

python-dateutil-2.0.tar.gz (Python >= 3.0)
python-dateutil-1.5.tar.gz (Python < 3.0)
python-dateutil-1.4.1.tar.gz
python-dateutil-1.4.tar.bz2
python-dateutil-1.3.tar.bz2
python-dateutil-1.2.tar.bz2
python-dateutil-1.1.tar.bz2
python-dateutil-1.0.tar.bz2

Author

The dateutil module was written by Gustavo Niemeyer <[email protected]>.

Documentation

The following modules are available.

relativedelta

This module offers the relativedelta type, which is based on the specification of the excelent work done by M.-A. Lemburg in his mxDateTime extension. However, notice that this type does not implement the same algorithm as his work. Do not expect it to behave like mxDateTime's counterpart.

relativedelta type

There's two different ways to build a relativedelta instance. The first one is passing it two date/datetime instances:

relativedelta(datetime1, datetime2)

This will build the relative difference between datetime1 and datetime2, so that the following constraint is always true:

datetime2+relativedelta(datetime1, datetime2) == datetime1

Notice that instead of datetime instances, you may use date instances, or a mix of both.

And the other way is to use any of the following keyword arguments:

year, month, day, hour, minute, second, microsecond: Absolute information.
years, months, weeks, days, hours, minutes, seconds, microseconds: Relative information, may be negative.
weekday: One of the weekday instances (MO, TU, etc). These instances may receive a parameter n, specifying the nth weekday, which could be positive or negative (like MO(+2) or MO(-3). Not specifying it is the same as specifying +1. You can also use an integer, where 0=MO. Notice that, for example, if the calculated date is already Monday, using MO or MO(+1) (which is the same thing in this context), won't change the day.
leapdays: Will add given days to the date found, but only if the computed year is a leap year and the computed date is post 28 of february.
yearday, nlyearday: Set the yearday or the non-leap year day (jump leap days).
These are converted to day/month/leapdays information.

Behavior of operations

If you're curious about how exactly the relative delta will act on operations, here is a description of its behavior.

Calculate the absolute year, using the year argument, or the original datetime year, if the argument is not present.
Add the relative years argument to the absolute year.
Do steps 1 and 2 for month/months.
Calculate the absolute day, using the day argument, or the original datetime day, if the argument is not present. Then, subtract from the day until it fits in the year and month found after their operations.
Add the relative days argument to the absolute day. Notice that the weeks argument is multiplied by 7 and added to days.
If leapdays is present, the computed year is a leap year, and the computed month is after february, remove one day from the found date.
Do steps 1 and 2 for hour/hours, minute/minutes, second/seconds, microsecond/microseconds.
If the weekday argument is present, calculate the nth occurrence of the given weekday.

Examples

Let's begin our trip.

>>> from datetime import *; from dateutil.relativedelta import *
>>> import calendar

Store some values.

>>> NOW = datetime.now()
>>> TODAY = date.today()
>>> NOW
datetime.datetime(2003, 9, 17, 20, 54, 47, 282310)
>>> TODAY
datetime.date(2003, 9, 17)

Next month.

>>> NOW+relativedelta(months=+1)
datetime.datetime(2003, 10, 17, 20, 54, 47, 282310)

Next month, plus one week.

>>> NOW+relativedelta(months=+1, weeks=+1)
datetime.datetime(2003, 10, 24, 20, 54, 47, 282310)

Next month, plus one week, at 10am.

>>> TODAY+relativedelta(months=+1, weeks=+1, hour=10)
datetime.datetime(2003, 10, 24, 10, 0)

Let's try the other way around. Notice that the hour setting we get in the relativedelta is relative, since it's a difference, and the weeks parameter has gone.

>>> relativedelta(datetime(2003, 10, 24, 10, 0), TODAY)
relativedelta(months=+1, days=+7, hours=+10)

One month before one year.

>>> NOW+relativedelta(years=+1, months=-1)
datetime.datetime(2004, 8, 17, 20, 54, 47, 282310)

How does it handle months with different numbers of days? Notice that adding one month will never cross the month boundary.

>>> date(2003,1,27)+relativedelta(months=+1)
datetime.date(2003, 2, 27)
>>> date(2003,1,31)+relativedelta(months=+1)
datetime.date(2003, 2, 28)
>>> date(2003,1,31)+relativedelta(months=+2)
datetime.date(2003, 3, 31)

The logic for years is the same, even on leap years.

>>> date(2000,2,28)+relativedelta(years=+1)
datetime.date(2001, 2, 28)
>>> date(2000,2,29)+relativedelta(years=+1)
datetime.date(2001, 2, 28)

>>> date(1999,2,28)+relativedelta(years=+1)
datetime.date(2000, 2, 28)
>>> date(1999,3,1)+relativedelta(years=+1)
datetime.date(2000, 3, 1)

>>> date(2001,2,28)+relativedelta(years=-1)
datetime.date(2000, 2, 28)
>>> date(2001,3,1)+relativedelta(years=-1)
datetime.date(2000, 3, 1)

Next friday.

>>> TODAY+relativedelta(weekday=FR)
datetime.date(2003, 9, 19)

>>> TODAY+relativedelta(weekday=calendar.FRIDAY)
datetime.date(2003, 9, 19)

Last friday in this month.

>>> TODAY+relativedelta(day=31, weekday=FR(-1))
datetime.date(2003, 9, 26)

Next wednesday (it's today!).

>>> TODAY+relativedelta(weekday=WE(+1))
datetime.date(2003, 9, 17)

Next wednesday, but not today.

>>> TODAY+relativedelta(days=+1, weekday=WE(+1))
datetime.date(2003, 9, 24)

Following ISO year week number notation find the first day of the 15th week of 1997.

>>> datetime(1997,1,1)+relativedelta(day=4, weekday=MO(-1), weeks=+14)
datetime.datetime(1997, 4, 7, 0, 0)

How long ago has the millennium changed?

>>> relativedelta(NOW, date(2001,1,1))
relativedelta(years=+2, months=+8, days=+16,
              hours=+20, minutes=+54, seconds=+47, microseconds=+282310)

How old is John?

>>> johnbirthday = datetime(1978, 4, 5, 12, 0)
>>> relativedelta(NOW, johnbirthday)
relativedelta(years=+25, months=+5, days=+12,
              hours=+8, minutes=+54, seconds=+47, microseconds=+282310)

It works with dates too.

>>> relativedelta(TODAY, johnbirthday)
relativedelta(years=+25, months=+5, days=+11, hours=+12)

Obtain today's date using the yearday:

>>> date(2003, 1, 1)+relativedelta(yearday=260)
datetime.date(2003, 9, 17)

We can use today's date, since yearday should be absolute in the given year:

>>> TODAY+relativedelta(yearday=260)
datetime.date(2003, 9, 17)

Last year it should be in the same day:

>>> date(2002, 1, 1)+relativedelta(yearday=260)
datetime.date(2002, 9, 17)

But not in a leap year:

>>> date(2000, 1, 1)+relativedelta(yearday=260)
datetime.date(2000, 9, 16)

We can use the non-leap year day to ignore this:

>>> date(2000, 1, 1)+relativedelta(nlyearday=260)
datetime.date(2000, 9, 17)

rrule

The rrule module offers a small, complete, and very fast, implementation of the recurrence rules documented in the iCalendar RFC, including support for caching of results.

rrule type

That's the base of the rrule operation. It accepts all the keywords defined in the RFC as its constructor parameters (except byday, which was renamed to byweekday) and more. The constructor prototype is:

rrule(freq)

Where freq must be one of YEARLY, MONTHLY, WEEKLY, DAILY, HOURLY, MINUTELY, or SECONDLY.

Additionally, it supports the following keyword arguments:

cache: If given, it must be a boolean value specifying to enable or disable caching of results. If you will use the same
rrule instance multiple times, enabling caching will improve the performance considerably.
dtstart: The recurrence start. Besides being the base for the recurrence, missing parameters in the final recurrence instances will also be extracted from this date. If not
given, datetime.now() will be used instead.
interval: The interval between each freq iteration. For example, when using YEARLY, an interval of 2 means once every two years, but with HOURLY, it means once every two hours. The default interval is 1.
wkst: The week start day. Must be one of the MO, TU, WE constants, or an integer, specifying the first day of the week. This will affect recurrences based on weekly periods. The default week start is got from calendar.firstweekday(), and may be modified by calendar.setfirstweekday().
count: How many occurrences will be generated.
until: If given, this must be a datetime instance, that will specify the limit of the recurrence. If a recurrence instance happens to be the same as the datetime instance given in the until keyword, this will be the last occurrence.
bysetpos: If given, it must be either an integer, or a sequence of integers, positive or negative. Each given integer will specify an occurrence number, corresponding to the nth occurrence of the rule inside the frequency period. For
example, a bysetpos of -1 if combined with a MONTHLY frequency, and a byweekday of (MO, TU, WE, TH, FR), will result in the last work day of every month.
bymonth: If given, it must be either an integer, or a sequence of integers, meaning the months to apply the recurrence to.
bymonthday: If given, it must be either an integer, or a sequence of integers, meaning the month days to apply the recurrence to.
byyearday: If given, it must be either an integer, or a sequence of integers, meaning the year days to apply the recurrence to.
byweekno: If given, it must be either an integer, or a sequence of integers, meaning the week numbers to apply the recurrence to. Week numbers have the meaning described in ISO8601, that is, the first week of the year is that containing at least four days of the new year.
byweekday: If given, it must be either an integer (0 == MO), a sequence of integers, one of the weekday constants (MO, TU, etc), or a sequence of these constants. When given, these variables will define the weekdays where the recurrence will be applied. It's also possible to use an argument n for the weekday instances, which will mean the nth occurrence of this weekday in the period. For example, with MONTHLY, or with YEARLY and BYMONTH, using FR(+1) in byweekday will specify the first friday of the month where the recurrence happens. Notice that in the RFC documentation, this is specified as BYDAY, but was renamed to avoid the ambiguity of that keyword.
byhour: If given, it must be either an integer, or a sequence of integers, meaning the hours to apply the recurrence to.
byminute: If given, it must be either an integer, or a sequence of integers, meaning the minutes to apply the recurrence to.
bysecond: If given, it must be either an integer, or a sequence of integers, meaning the seconds to apply the recurrence to.
byeaster: If given, it must be either an integer, or a sequence of integers, positive or negative. Each integer will define an offset from the Easter Sunday. Passing the offset
0 to byeaster will yield the Easter Sunday itself. This is an extension to the RFC specification.

rrule frequencies

The rrule frequency denotes the period on which the rule is evaluated. Multiple dates may match in a single period, and none may match as well, depending on the rule itself. In other words, the rule won't be adapted to ensure that a match necessarily happens inside the given frequency, and if multiple entries match the rule they will be returned.

Note, for instance, the two rules:

>>> list(rrule(DAILY, count=3, byweekday=(TU,TH),
...            dtstart=datetime(2007,1,1)))
[datetime.datetime(2007, 1, 2, 0, 0),
 datetime.datetime(2007, 1, 4, 0, 0),
 datetime.datetime(2007, 1, 9, 0, 0)]

>>> list(rrule(WEEKLY, count=3, byweekday=(TU,TH),
...            dtstart=datetime(2007,1,1)))
[datetime.datetime(2007, 1, 2, 0, 0),
 datetime.datetime(2007, 1, 4, 0, 0),
 datetime.datetime(2007, 1, 9, 0, 0)]
>>

In this case, they have the same meaning. The only difference is the way that they were generated. Now, notice the change if we include a bysetpos option.

>>> list(rrule(DAILY, count=3, byweekday=(TU,TH), bysetpos=1,
...            dtstart=datetime(2007,1,1)))
[datetime.datetime(2007, 1, 2, 0, 0),
 datetime.datetime(2007, 1, 4, 0, 0),
 datetime.datetime(2007, 1, 9, 0, 0)]


>>> list(rrule(WEEKLY, count=3, byweekday=(TU,TH), bysetpos=1,
...            dtstart=datetime(2007,1,1)))
[datetime.datetime(2007, 1, 2, 0, 0),
 datetime.datetime(2007, 1, 9, 0, 0),
 datetime.datetime(2007, 1, 16, 0, 0)]

In both cases, only the first matching entry inside the given period was considered a match.

It is also important to note that specifying only the frequency will result in the relevant byXXX rule parts being retrieved from the dtstart value. For instance:

rrule(MONTHLY, dtstart=datetime(2007,1,2))

This would assume bymonthday=2, byhour=0, byminute=0, and so would generate date values for Jan 2nd, Feb 2nd, Mar 2nd, and so on. If, on the other hand, the start date is on Jan 31st:

rrule(MONTHLY, dtstart=datetime(2007,1,31))

This would only generate values for 31st Jan, 31st Mar, 31st May, etc. Any month with less than 31 days is ignored.

To generate a rrule for the use case of "a date on the specified day of the month, unless it is beyond the end of month, in which case it will be the last day of the month" use the following:

rrule(MONTHLY, bymonthday=(some_day, -1), bysetpos=1)

This will generate a value for every calendar month regardless of the day of the month it is started from.

For more details, check the iCalendar RFC.

rrule methods

The following methods are available in rrule instances:

rrule.before(dt, inc=False): Returns the last recurrence before the given datetime instance. The inc keyword defines what happens if dt is an occurrence. With inc == True, if dt itself is an occurrence, it will be returned.
rrule.after(dt, inc=False): Returns the first recurrence after the given datetime instance. The inc keyword defines what happens if dt is an occurrence. With inc == True, if dt itself is an occurrence, it will be returned.
rrule.between(after, before, inc=False): Returns all the occurrences of the rrule between after and before. The inc keyword defines what happens if after and/or before are themselves occurrences. With inc == True, they will be included in the list, if they are found in the recurrence set.
rrule.count(): Returns the number of recurrences in this set. It will have go trough the whole recurrence, if this hasn't been done before.

Besides these methods, rrule instances also support the __getitem__() and __contains__() special methods, meaning that these are valid expressions:

rr = rrule(...)
if datetime(...) in rr:
    ...
print rr[0]
print rr[-1]
print rr[1:2]
print rr[::-2]

The getitem/slicing mechanism is smart enough to avoid getting the whole recurrence set, if possible.

Notes

The rrule type has no byday keyword. The equivalent keyword has been replaced by the byweekday keyword, to remove the ambiguity present in the original keyword.
Unlike documented in the RFC, the starting datetime (dtstart) is not the first recurrence instance, unless it does fit in the specified rules. In a python module context, this behavior makes more sense than otherwise. Notice that you can easily get the original behavior by using a rruleset and adding the dtstart as an rdate recurrence.
Unlike documented in the RFC, every keyword is valid on every
frequency (the RFC documents that byweekno is only valid on yearly frequencies, for example).
In addition to the documented keywords, a byeaster keyword was introduced, making it easy to compute recurrent events relative to the Easter Sunday.

rrule examples

These examples were converted from the RFC.

Prepare the environment.

>>> from dateutil.rrule import *
>>> from dateutil.parser import *
>>> from datetime import *

>>> import pprint
>>> import sys
>>> sys.displayhook = pprint.pprint

Daily, for 10 occurrences.

>>> list(rrule(DAILY, count=10,
               dtstart=parse("19970902T090000")))
[datetime.datetime(1997, 9, 2, 9, 0),
 datetime.datetime(1997, 9, 3, 9, 0),
 datetime.datetime(1997, 9, 4, 9, 0),
 datetime.datetime(1997, 9, 5, 9, 0),
 datetime.datetime(1997, 9, 6, 9, 0),
 datetime.datetime(1997, 9, 7, 9, 0),
 datetime.datetime(1997, 9, 8, 9, 0),
 datetime.datetime(1997, 9, 9, 9, 0),
 datetime.datetime(1997, 9, 10, 9, 0),
 datetime.datetime(1997, 9, 11, 9, 0)]

Daily until December 24, 1997

>>> list(rrule(DAILY,
               dtstart=parse("19970902T090000"),
               until=parse("19971224T000000")))
[datetime.datetime(1997, 9, 2, 9, 0),
 datetime.datetime(1997, 9, 3, 9, 0),
 datetime.datetime(1997, 9, 4, 9, 0),
 (...)
 datetime.datetime(1997, 12, 21, 9, 0),
 datetime.datetime(1997, 12, 22, 9, 0),
 datetime.datetime(1997, 12, 23, 9, 0)]

Every other day, 5 occurrences.

>>> list(rrule(DAILY, interval=2, count=5,
               dtstart=parse("19970902T090000")))
[datetime.datetime(1997, 9, 2, 9, 0),
 datetime.datetime(1997, 9, 4, 9, 0),
 datetime.datetime(1997, 9, 6, 9, 0),
 datetime.datetime(1997, 9, 8, 9, 0),
 datetime.datetime(1997, 9, 10, 9, 0)]

Every 10 days, 5 occurrences.

>>> list(rrule(DAILY, interval=10, count=5,
               dtstart=parse("19970902T090000")))
[datetime.datetime(1997, 9, 2, 9, 0),
 datetime.datetime(1997, 9, 12, 9, 0),
 datetime.datetime(1997, 9, 22, 9, 0),
 datetime.datetime(1997, 10, 2, 9, 0),
 datetime.datetime(1997, 10, 12, 9, 0)]

Everyday in January, for 3 years.

>>> list(rrule(YEARLY, bymonth=1, byweekday=range(7),
               dtstart=parse("19980101T090000"),
               until=parse("20000131T090000")))
[datetime.datetime(1998, 1, 1, 9, 0),
 datetime.datetime(1998, 1, 2, 9, 0),
 (...)
 datetime.datetime(1998, 1, 30, 9, 0),
 datetime.datetime(1998, 1, 31, 9, 0),
 datetime.datetime(1999, 1, 1, 9, 0),
 datetime.datetime(1999, 1, 2, 9, 0),
 (...)
 datetime.datetime(1999, 1, 30, 9, 0),
 datetime.datetime(1999, 1, 31, 9, 0),
 datetime.datetime(2000, 1, 1, 9, 0),
 datetime.datetime(2000, 1, 2, 9, 0),
 (...)
 datetime.datetime(2000, 1, 29, 9, 0),
 datetime.datetime(2000, 1, 31, 9, 0)]

Same thing, in another way.

>>> list(rrule(DAILY, bymonth=1,
               dtstart=parse("19980101T090000"),
               until=parse("20000131T090000")))
(...)

Weekly for 10 occurrences.

>>> list(rrule(WEEKLY, count=10,
               dtstart=parse("19970902T090000")))
[datetime.datetime(1997, 9, 2, 9, 0),
 datetime.datetime(1997, 9, 9, 9, 0),
 datetime.datetime(1997, 9, 16, 9, 0),
 datetime.datetime(1997, 9, 23, 9, 0),
 datetime.datetime(1997, 9, 30, 9, 0),
 datetime.datetime(1997, 10, 7, 9, 0),
 datetime.datetime(1997, 10, 14, 9, 0),
 datetime.datetime(1997, 10, 21, 9, 0),
 datetime.datetime(1997, 10, 28, 9, 0),
 datetime.datetime(1997, 11, 4, 9, 0)]

Every other week, 6 occurrences.

>>> list(rrule(WEEKLY, interval=2, count=6,
               dtstart=parse("19970902T090000")))
[datetime.datetime(1997, 9, 2, 9, 0),
 datetime.datetime(1997, 9, 16, 9, 0),
 datetime.datetime(1997, 9, 30, 9, 0),
 datetime.datetime(1997, 10, 14, 9, 0),
 datetime.datetime(1997, 10, 28, 9, 0),
 datetime.datetime(1997, 11, 11, 9, 0)]

Weekly on Tuesday and Thursday for 5 weeks.

>>> list(rrule(WEEKLY, count=10, wkst=SU, byweekday=(TU,TH),
               dtstart=parse("19970902T090000")))
[datetime.datetime(1997, 9, 2, 9, 0),
 datetime.datetime(1997, 9, 4, 9, 0),
 datetime.datetime(1997, 9, 9, 9, 0),
 datetime.datetime(1997, 9, 11, 9, 0),
 datetime.datetime(1997, 9, 16, 9, 0),
 datetime.datetime(1997, 9, 18, 9, 0),
 datetime.datetime(1997, 9, 23, 9, 0),
 datetime.datetime(1997, 9, 25, 9, 0),
 datetime.datetime(1997, 9, 30, 9, 0),
 datetime.datetime(1997, 10, 2, 9, 0)]

Every other week on Tuesday and Thursday, for 8 occurrences.

>>> list(rrule(WEEKLY, interval=2, count=8,
               wkst=SU, byweekday=(TU,TH),
               dtstart=parse("19970902T090000")))
[datetime.datetime(1997, 9, 2, 9, 0),
 datetime.datetime(1997, 9, 4, 9, 0),
 datetime.datetime(1997, 9, 16, 9, 0),
 datetime.datetime(1997, 9, 18, 9, 0),
 datetime.datetime(1997, 9, 30, 9, 0),
 datetime.datetime(1997, 10, 2, 9, 0),
 datetime.datetime(1997, 10, 14, 9, 0),
 datetime.datetime(1997, 10, 16, 9, 0)]

Monthly on the 1st Friday for ten occurrences.

>>> list(rrule(MONTHLY, count=10, byweekday=FR(1),
               dtstart=parse("19970905T090000")))
[datetime.datetime(1997, 9, 5, 9, 0),
 datetime.datetime(1997, 10, 3, 9, 0),
 datetime.datetime(1997, 11, 7, 9, 0),
 datetime.datetime(1997, 12, 5, 9, 0),
 datetime.datetime(1998, 1, 2, 9, 0),
 datetime.datetime(1998, 2, 6, 9, 0),
 datetime.datetime(1998, 3, 6, 9, 0),
 datetime.datetime(1998, 4, 3, 9, 0),
 datetime.datetime(1998, 5, 1, 9, 0),
 datetime.datetime(1998, 6, 5, 9, 0)]

Every other month on the 1st and last Sunday of the month for 10 occurrences.

>>> list(rrule(MONTHLY, interval=2, count=10,
               byweekday=(SU(1), SU(-1)),
               dtstart=parse("19970907T090000")))
[datetime.datetime(1997, 9, 7, 9, 0),
 datetime.datetime(1997, 9, 28, 9, 0),
 datetime.datetime(1997, 11, 2, 9, 0),
 datetime.datetime(1997, 11, 30, 9, 0),
 datetime.datetime(1998, 1, 4, 9, 0),
 datetime.datetime(1998, 1, 25, 9, 0),
 datetime.datetime(1998, 3, 1, 9, 0),
 datetime.datetime(1998, 3, 29, 9, 0),
 datetime.datetime(1998, 5, 3, 9, 0),
 datetime.datetime(1998, 5, 31, 9, 0)]

Monthly on the second to last Monday of the month for 6 months.

>>> list(rrule(MONTHLY, count=6, byweekday=MO(-2),
               dtstart=parse("19970922T090000")))
[datetime.datetime(1997, 9, 22, 9, 0),
 datetime.datetime(1997, 10, 20, 9, 0),
 datetime.datetime(1997, 11, 17, 9, 0),
 datetime.datetime(1997, 12, 22, 9, 0),
 datetime.datetime(1998, 1, 19, 9, 0),
 datetime.datetime(1998, 2, 16, 9, 0)]

Monthly on the third to the last day of the month, for 6 months.

>>> list(rrule(MONTHLY, count=6, bymonthday=-3,
               dtstart=parse("19970928T090000")))
[datetime.datetime(1997, 9, 28, 9, 0),
 datetime.datetime(1997, 10, 29, 9, 0),
 datetime.datetime(1997, 11, 28, 9, 0),
 datetime.datetime(1997, 12, 29, 9, 0),
 datetime.datetime(1998, 1, 29, 9, 0),
 datetime.datetime(1998, 2, 26, 9, 0)]

Monthly on the 2nd and 15th of the month for 5 occurrences.

>>> list(rrule(MONTHLY, count=5, bymonthday=(2,15),
               dtstart=parse("19970902T090000")))
[datetime.datetime(1997, 9, 2, 9, 0),
 datetime.datetime(1997, 9, 15, 9, 0),
 datetime.datetime(1997, 10, 2, 9, 0),
 datetime.datetime(1997, 10, 15, 9, 0),
 datetime.datetime(1997, 11, 2, 9, 0)]

Monthly on the first and last day of the month for 3 occurrences.

>>> list(rrule(MONTHLY, count=5, bymonthday=(-1,1,),
               dtstart=parse("1997090
2T090000")))
[datetime.datetime(1997, 9, 30, 9, 0),
 datetime.datetime(1997, 10, 1, 9, 0),
 datetime.datetime(1997, 10, 31, 9, 0),
 datetime.datetime(1997, 11, 1, 9, 0),
 datetime.datetime(1997, 11, 30, 9, 0)]

Every 18 months on the 10th thru 15th of the month for 10 occurrences.

>>> list(rrule(MONTHLY, interval=18, count=10,
               bymonthday=range(10,16),
               dtstart=parse("19970910T090000")))
[datetime.datetime(1997, 9, 10, 9, 0),
 datetime.datetime(1997, 9, 11, 9, 0),
 datetime.datetime(1997, 9, 12, 9, 0),
 datetime.datetime(1997, 9, 13, 9, 0),
 datetime.datetime(1997, 9, 14, 9, 0),
 datetime.datetime(1997, 9, 15, 9, 0),
 datetime.datetime(1999, 3, 10, 9, 0),
 datetime.datetime(1999, 3, 11, 9, 0),
 datetime.datetime(1999, 3, 12, 9, 0),
 datetime.datetime(1999, 3, 13, 9, 0)]

Every Tuesday, every other month, 6 occurences.

>>> list(rrule(MONTHLY, interval=2, count=6, byweekday=TU,
               dtstart=parse("19970902T090000")))
[datetime.datetime(1997, 9, 2, 9, 0),
 datetime.datetime(1997, 9, 9, 9, 0),
 datetime.datetime(1997, 9, 16, 9, 0),
 datetime.datetime(1997, 9, 23, 9, 0),
 datetime.datetime(1997, 9, 30, 9, 0),
 datetime.datetime(1997, 11, 4, 9, 0)]

Yearly in June and July for 10 occurrences.

>>> list(rrule(YEARLY, count=4, bymonth=(6,7),
               dtstart=parse("19970610T0900
00")))
[datetime.datetime(1997, 6, 10, 9, 0),
 datetime.datetime(1997, 7, 10, 9, 0),
 datetime.datetime(1998, 6, 10, 9, 0),
 datetime.datetime(1998, 7, 10, 9, 0)]

Every 3rd year on the 1st, 100th and 200th day for 4 occurrences.

>>> list(rrule(YEARLY, count=4, interval=3, byyearday=(1,100,200),
               dtstart=parse("19970101T090000")))
[datetime.datetime(1997, 1, 1, 9, 0),
 datetime.datetime(1997, 4, 10, 9, 0),
 datetime.datetime(1997, 7, 19, 9, 0),
 datetime.datetime(2000, 1, 1, 9, 0)]

Every 20th Monday of the year, 3 occurrences.

>>> list(rrule(YEARLY, count=3, byweekday=MO(20),
               dtstart=parse("19970519T090000")))
[datetime.datetime(1997, 5, 19, 9, 0),
 datetime.datetime(1998, 5, 18, 9, 0),
 datetime.datetime(1999, 5, 17, 9, 0)]

Monday of week number 20 (where the default start of the week is Monday), 3 occurrences.

>>> list(rrule(YEARLY, count=3, byweekno=20, byweekday=MO,
               dtstart=parse("19970512T090000")))
[datetime.datetime(1997, 5, 12, 9, 0),
 datetime.datetime(1998, 5, 11, 9, 0),
 datetime.datetime(1999, 5, 17, 9, 0)]

The week number 1 may be in the last year.

>>> list(rrule(WEEKLY, count=3, byweekno=1, byweekday=MO,
               dtstart=parse("19970902T090000")))
[datetime.datetime(1997, 12, 29, 9, 0),
 datetime.datetime(1999, 1, 4, 9, 0),
 datetime.datetime(2000, 1, 3, 9, 0)]

And the week numbers greater than 51 may be in the next year.

>>> list(rrule(WEEKLY, count=3, byweekno=52, byweekday=SU,
               dtstart=parse("19970902T090000")))
[datetime.datetime(1997, 12, 28, 9, 0),
 datetime.datetime(1998, 12, 27, 9, 0),
 datetime.datetime(2000, 1, 2, 9, 0)]

Only some years have week number 53:

>>> list(rrule(WEEKLY, count=3, byweekno=53, byweekday=MO,
               dtstart=parse("19970902T090000")))
[datetime.datetime(1998, 12, 28, 9, 0),
 datetime.datetime(2004, 12, 27, 9, 0),
 datetime.datetime(2009, 12, 28, 9, 0)]

Every Friday the 13th, 4 occurrences.

>>> list(rrule(YEARLY, count=4, byweekday=FR, bymonthday=13,
               dtstart=parse("19970902T090000")))
[datetime.datetime(1998, 2, 13, 9, 0),
 datetime.datetime(1998, 3, 13, 9, 0),
 datetime.datetime(1998, 11, 13, 9, 0),
 datetime.datetime(1999, 8, 13, 9, 0)]

Every four years, the first Tuesday after a Monday in November, 3 occurrences (U.S. Presidential Election day):

>>> list(rrule(YEARLY, interval=4, count=3, bymonth=11,
               byweekday=TU, bymonthday=(2,3,4,5,6,7,8),
               dtstart=parse("19961105T090000")))
[datetime.datetime(1996, 11, 5, 9, 0),
 datetime.datetime(2000, 11, 7, 9, 0),
 datetime.datetime(2004, 11, 2, 9, 0)]

The 3rd instance into the month of one of Tuesday, Wednesday or Thursday, for the next 3 months:

>>> list(rrule(MONTHLY, count=3, byweekday=(TU,WE,TH),
               bysetpos=3, dtstart=parse("19970904T090000")))
[datetime.datetime(1997, 9, 4, 9, 0),
 datetime.datetime(1997, 10, 7, 9, 0),
 datetime.datetime(1997, 11, 6, 9, 0)]

The 2nd to last weekday of the month, 3 occurrences.

>>> list(rrule(MONTHLY, count=3, byweekday=(MO,TU,WE,TH,FR),
               bysetpos=-2, dtstart=parse("19970929T090000")))
[datetime.datetime(1997, 9, 29, 9, 0),
 datetime.datetime(1997, 10, 30, 9, 0),
 datetime.datetime(1997, 11, 27, 9, 0)]

Every 3 hours from 9:00 AM to 5:00 PM on a specific day.

>>> list(rrule(HOURLY, interval=3,
               dtstart=parse("19970902T090000"),
               until=parse("19970902T170000")))
[datetime.datetime(1997, 9, 2, 9, 0),
 datetime.datetime(1997, 9, 2, 12, 0),
 datetime.datetime(1997, 9, 2, 15, 0)]

Every 15 minutes for 6 occurrences.

>>> list(rrule(MINUTELY, interval=15, count=6,
               dtstart=parse("19970902T090000")))
[datetime.datetime(1997, 9, 2, 9, 0),
 datetime.datetime(1997, 9, 2, 9, 15),
 datetime.datetime(1997, 9, 2, 9, 30),
 datetime.datetime(1997, 9, 2, 9, 45),
 datetime.datetime(1997, 9, 2, 10, 0),
 datetime.datetime(1997, 9, 2, 10, 15)]

Every hour and a half for 4 occurrences.

>>> list(rrule(MINUTELY, interval=90, count=4,
               dtstart=parse("19970902T090000")))
[datetime.datetime(1997, 9, 2, 9, 0),
 datetime.datetime(1997, 9, 2, 10, 30),
 datetime.datetime(1997, 9, 2, 12, 0),
 datetime.datetime(1997, 9, 2, 13, 30)]

Every 20 minutes from 9:00 AM to 4:40 PM for two days.

>>> list(rrule(MINUTELY, interval=20, count=48,
               byhour=range(9,17), byminute=(0,20,40),
               dtstart=parse("19970902T090000")))
[datetime.datetime(1997, 9, 2, 9, 0),
 datetime.datetime(1997, 9, 2, 9, 20),
 (...)
 datetime.datetime(1997, 9, 2, 16, 20),
 datetime.datetime(1997, 9, 2, 16, 40),
 datetime.datetime(1997, 9, 3, 9, 0),
 datetime.datetime(1997, 9, 3, 9, 20),
 (...)
 datetime.datetime(1997, 9, 3, 16, 20),
 datetime.datetime(1997, 9, 3, 16, 40)]

An example where the days generated makes a difference because of wkst.

>>> list(rrule(WEEKLY, interval=2, count=4,
               byweekday=(TU,SU), wkst=MO,
               dtstart=parse("19970805T090000")))
[datetime.datetime(1997, 8, 5, 9, 0),
 datetime.datetime(1997, 8, 10, 9, 0),
 datetime.datetime(1997, 8, 19, 9, 0),
 datetime.datetime(1997, 8, 24, 9, 0)]

>>> list(rrule(WEEKLY, interval=2, count=4,
               byweekday=(TU,SU), wkst=SU,
               dtstart=parse("19970805T090000")))
[datetime.datetime(1997, 8, 5, 9, 0),
 datetime.datetime(1997, 8, 17, 9, 0),
 datetime.datetime(1997, 8, 19, 9, 0),
 datetime.datetime(1997, 8, 31, 9, 0)]

rruleset type

The rruleset type allows more complex recurrence setups, mixing multiple rules, dates, exclusion rules, and exclusion dates. The type constructor takes the following keyword arguments:

cache: If True, caching of results will be enabled, improving performance of multiple queries considerably.

rruleset methods

The following methods are available:

rruleset.rrule(rrule): Include the given rrule instance in the recurrence set generation.
rruleset.rdate(dt): Include the given datetime instance in the recurrence set generation.
rruleset.exrule(rrule): Include the given rrule instance in the recurrence set exclusion list. Dates which are part of the given recurrence rules will not be generated, even if some inclusive rrule or rdate matches them.
rruleset.exdate(dt): Include the given datetime instance in the recurrence set exclusion list. Dates included that way will not be generated, even if some inclusive rrule or rdate matches them.
rruleset.before(dt, inc=False): Returns the last recurrence before the given datetime instance. The inc keyword defines what happens if dt is an occurrence. With inc == True, if dt itself is an occurrence, it will be returned.
rruleset.after(dt, inc=False): Returns the first recurrence after the given datetime instance. The inc keyword defines what happens if dt is an occurrence. With inc == True, if dt itself is an occurrence, it will be returned.
rruleset.between(after, before, inc=False): Returns all the occurrences of the rrule between after and before. The inc keyword defines what happens if after and/or before are themselves occurrences. With inc == True, they will be included in the list, if they are found in the recurrence set.
rruleset.count(): Returns the number of recurrences in this set. It will have go trough the whole recurrence, if this hasn't been done before.

Besides these methods, rruleset instances also support the __getitem__() and __contains__() special methods, meaning that these are valid expressions:

set = rruleset(...)
if datetime(...) in set:
    ...
print set[0]
print set[-1]
print set[1:2]
print set[::-2]

The getitem/slicing mechanism is smart enough to avoid getting the whole recurrence set, if possible.

rruleset examples

Daily, for 7 days, jumping Saturday and Sunday occurrences.

>>> set = rruleset()
>>> set.rrule(rrule(DAILY, count=7,
                    dtstart=parse("19970902T090000")))
>>> set.exrule(rrule(YEARLY, byweekday=(SA,SU),
                     dtstart=parse("19970902T090000")))
>>> list(set)
[datetime.datetime(1997, 9, 2, 9, 0),
 datetime.datetime(1997, 9, 3, 9, 0),
 datetime.datetime(1997, 9, 4, 9, 0),
 datetime.datetime(1997, 9, 5, 9, 0),
 datetime.datetime(1997, 9, 8, 9, 0)]

Weekly, for 4 weeks, plus one time on day 7, and not on day 16.

>>> set = rruleset()
>>> set.rrule(rrule(WEEKLY, count=4,
                    dtstart=parse("19970902T090000")))
>>> set.rdate(datetime.datetime(1997, 9, 7, 9, 0))
>>> set.exdate(datetime.datetime(1997, 9, 16, 9, 0))
>>> list(set)
[datetime.datetime(1997, 9, 2, 9, 0),
 datetime.datetime(1997, 9, 7, 9, 0),
 datetime.datetime(1997, 9, 9, 9, 0),
 datetime.datetime(1997, 9, 23, 9, 0)]

rrulestr() function

The rrulestr() function is a parser for RFC-like syntaxes. The function prototype is:

rrulestr(str)

The string passed as parameter may be a multiple line string, a single line string, or just the RRULE property value.

Additionally, it accepts the following keyword arguments:

cache: If True, the rruleset or rrule created instance will cache its results. Default is not to cache.
dtstart: If given, it must be a datetime instance that will be used when no DTSTART property is found in the parsed string. If it is not given, and the property is not found, datetime.now() will be used instead.
unfold: If set to True, lines will be unfolded following the RFC specification. It defaults to False, meaning that spaces before every line will be stripped.
forceset: If set to True a rruleset instance will be returned, even if only a single rule is found. The default is to return an rrule if possible, and an rruleset if necessary.
compatible: If set to True, the parser will operate in RFC-compatible mode. Right now it means that unfold will be turned on, and if a DTSTART is found, it will be considered the first recurrence instance, as documented in the RFC.
ignoretz: If set to True, the date parser will ignore timezone information available in the DTSTART property, or the UNTIL attribute.
tzinfos: If set, it will be passed to the datetime string parser to resolve unknown timezone settings. For more information about what could be used here, check the parser documentation.

rrulestr() examples

Every 10 days, 5 occurrences.

>>> list(rrulestr("""
... DTSTART:19970902T090000
... RRULE:FREQ=DAILY;INTERVAL=10;COUNT=5
... """))
[datetime.datetime(1997, 9, 2, 9, 0),
 datetime.datetime(1997, 9, 12, 9, 0),
 datetime.datetime(1997, 9, 22, 9, 0),
 datetime.datetime(1997, 10, 2, 9, 0),
 datetime.datetime(1997, 10, 12, 9, 0)]

Same thing, but passing only the RRULE value.

>>> list(rrulestr("FREQ=DAILY;INTERVAL=10;COUNT=5",
                  dtstart=parse("19970902T090000")))
[datetime.datetime(1997, 9, 2, 9, 0),
 datetime.datetime(1997, 9, 12, 9, 0),
 datetime.datetime(1997, 9, 22, 9, 0),
 datetime.datetime(1997, 10, 2, 9, 0),
 datetime.datetime(1997, 10, 12, 9, 0)]

Notice that when using a single rule, it returns an rrule instance, unless forceset was used.

>>> rrulestr("FREQ=DAILY;INTERVAL=10;COUNT=5")
<dateutil.rrule.rrule instance at 0x30269f08>

>>> rrulestr("""
... DTSTART:19970902T090000
... RRULE:FREQ=DAILY;INTERVAL=10;COUNT=5
... """)
<dateutil.rrule.rrule instance at 0x302699e0>

>>> rrulestr("FREQ=DAILY;INTERVAL=10;COUNT=5", forceset=True)
<dateutil.rrule.rruleset instance at 0x30269f08>

But when an rruleset is needed, it is automatically used.

>>> rrulestr("""
... DTSTART:19970902T090000
... RRULE:FREQ=DAILY;INTERVAL=10;COUNT=5
... RRULE:FREQ=DAILY;INTERVAL=5;COUNT=3
... """)
<dateutil.rrule.rruleset instance at 0x302699e0>

parser

This module offers a generic date/time string parser which is able to parse most known formats to represent a date and/or time.

parse() function

That's probably the only function you'll need from this module. It offers you an interface to access the parser functionality and extract a datetime type out of a string.

The prototype of this function is:

parse(timestr)

Additionally, the following keyword arguments are available:

default: If given, this must be a datetime instance. Any fields missing in the parsed date will be copied from this instance. The default value is the current date, at 00:00:00am.
ignoretz: If this is true, even if a timezone is found in the string, the parser will not use it.
tzinfos: Using this keyword argument you may provide custom timezones to the parser. If given, it must be either a dictionary with the timezone abbreviation as key, or a function accepting a timezone abbreviation and offset as argument. The dictionary values and the function return must be a timezone offset in seconds, a tzinfo subclass, or a string defining the timezone (in the TZ environment variable format).
dayfirst: This option allow one to change the precedence in which days are parsed in date strings. The default is given in the parserinfo instance (the default parserinfo has it set to
False). If dayfirst is False, the MM-DD-YYYY format will have precedence over DD-MM-YYYY in an ambiguous date.
yearfirst: This option allow one to change the precedence in which years are parsed in date strings. The default is given in the parserinfo instance (the default parserinfo has it set
to False). If yearfirst is false, the MM-DD-YY format will have precedence over YY-MM-DD in an ambiguous date.
fuzzy: If fuzzy is set to True, unknown tokens in the string will be ignored.
parserinfo: This parameter allows one to change how the string is parsed, by using a different parserinfo class instance. Using it you may, for example, intenationalize the parser strings, or make it ignore additional words.

Format precedence

Whenever an ambiguous date is found, the dayfirst and yearfirst parameters will control how the information is processed. Here is the precedence in each case:

If dayfirst is False and yearfirst is False, (default, if no parameter is given):

MM-DD-YY
DD-MM-YY
YY-MM-DD

If dayfirst is True and yearfirst is False:

DD-MM-YY
MM-DD-YY
YY-MM-DD

If dayfirst is False and yearfirst is True:

YY-MM-DD
MM-DD-YY
DD-MM-YY

If dayfirst is True and yearfirst is True:

YY-MM-DD
DD-MM-YY
MM-DD-YY

Converting two digit years

When a two digit year is found, it is processed considering the current year, so that the computed year is never more than 49 years after then current year, nor 50 years before the current year. In other words, if we are in year 2003, and the year 30 is found, it will be considered as 2030, but if the year 60 is found, it will be considered 1960.

Examples

The following code will prepare the environment:

>>> from dateutil.parser import *
>>> from dateutil.tz import *
>>> from datetime import *
>>> TZOFFSETS = {"BRST": -10800}
>>> BRSTTZ = tzoffset(-10800, "BRST")
>>> DEFAULT = datetime(2003, 9, 25)

Some simple examples based on the date command, using the TZOFFSET dictionary to provide the BRST timezone offset.

>>> parse("Thu Sep 25 10:36:28 BRST 2003", tzinfos=TZOFFSETS)
datetime.datetime(2003, 9, 25, 10, 36, 28,
                  tzinfo=tzoffset('BRST', -10800))

>>> parse("2003 10:36:28 BRST 25 Sep Thu", tzinfos=TZOFFSETS)
datetime.datetime(2003, 9, 25, 10, 36, 28,
                  tzinfo=tzoffset('BRST', -10800))

Notice that since BRST is my local timezone, parsing it without further timezone settings will yield a tzlocal timezone.

>>> parse("Thu Sep 25 10:36:28 BRST 2003")
datetime.datetime(2003, 9, 25, 10, 36, 28, tzinfo=tzlocal())

We can also ask to ignore the timezone explicitly:

>>> parse("Thu Sep 25 10:36:28 BRST 2003", ignoretz=True)
datetime.datetime(2003, 9, 25, 10, 36, 28)

That's the same as processing a string without timezone:

>>> parse("Thu Sep 25 10:36:28 2003")
datetime.datetime(2003, 9, 25, 10, 36, 28)

Without the year, but passing our DEFAULT datetime to return the same year, no mattering what year we currently are in:

>>> parse("Thu Sep 25 10:36:28", default=DEFAULT)
datetime.datetime(2003, 9, 25, 10, 36, 28)

Strip it further:

>>> parse("Thu Sep 10:36:28", default=DEFAULT)
datetime.datetime(2003, 9, 25, 10, 36, 28)

>>> parse("Thu 10:36:28", default=DEFAULT)
datetime.datetime(2003, 9, 25, 10, 36, 28)

>>> parse("Thu 10:36", default=DEFAULT)
datetime.datetime(2003, 9, 25, 10, 36)

>>> parse("10:36", default=DEFAULT)
datetime.datetime(2003, 9, 25, 10, 36)
>>>

Strip in a different way:

>>> parse("Thu Sep 25 2003")
datetime.datetime(2003, 9, 25, 0, 0)

>>> parse("Sep 25 2003")
datetime.datetime(2003, 9, 25, 0, 0)

>>> parse("Sep 2003", default=DEFAULT)
datetime.datetime(2003, 9, 25, 0, 0)

>>> parse("Sep", default=DEFAULT)
datetime.datetime(2003, 9, 25, 0, 0)

>>> parse("2003", default=DEFAULT)
datetime.datetime(2003, 9, 25, 0, 0)

Another format, based on date -R (RFC822):

>>> parse("Thu, 25 Sep 2003 10:49:41 -0300")
datetime.datetime(2003, 9, 25, 10, 49, 41,
                  tzinfo=tzoffset(None, -10800))

ISO format:

>>> parse("2003-09-25T10:49:41.5-03:00")
datetime.datetime(2003, 9, 25, 10, 49, 41, 500000,
                  tzinfo=tzoffset(None, -10800))

Some variations:

>>> parse("2003-09-25T10:49:41")
datetime.datetime(2003, 9, 25, 10, 49, 41)

>>> parse("2003-09-25T10:49")
datetime.datetime(2003, 9, 25, 10, 49)

>>> parse("2003-09-25T10")
datetime.datetime(2003, 9, 25, 10, 0)

>>> parse("2003-09-25")
datetime.datetime(2003, 9, 25, 0, 0)

ISO format, without separators:

>>> parse("20030925T104941.5-0300")
datetime.datetime(2003, 9, 25, 10, 49, 41, 500000,
                  tzinfo=tzinfo=tzoffset(None, -10800))

>>> parse("20030925T104941-0300")
datetime.datetime(2003, 9, 25, 10, 49, 41,
                  tzinfo=tzoffset(None, -10800))

>>> parse("20030925T104941")
datetime.datetime(2003, 9, 25, 10, 49, 41)

>>> parse("20030925T1049")
datetime.datetime(2003, 9, 25, 10, 49)

>>> parse("20030925T10")
datetime.datetime(2003, 9, 25, 10, 0)

>>> parse("20030925")
datetime.datetime(2003, 9, 25, 0, 0)

Everything together.

>>> parse("199709020900")
datetime.datetime(1997, 9, 2, 9, 0)
>>> parse("19970902090059")
datetime.datetime(1997, 9, 2, 9, 0, 59)

Different date orderings:

>>> parse("2003-09-25")
datetime.datetime(2003, 9, 25, 0, 0)

>>> parse("2003-Sep-25")
datetime.datetime(2003, 9, 25, 0, 0)

>>> parse("25-Sep-2003")
datetime.datetime(2003, 9, 25, 0, 0)

>>> parse("Sep-25-2003")
datetime.datetime(2003, 9, 25, 0, 0)

>>> parse("09-25-2003")
datetime.datetime(2003, 9, 25, 0, 0)

>>> parse("25-09-2003")
datetime.datetime(2003, 9, 25, 0, 0)

Check some ambiguous dates:

>>> parse("10-09-2003")
datetime.datetime(2003, 10, 9, 0, 0)

>>> parse("10-09-2003", dayfirst=True)
datetime.datetime(2003, 9, 10, 0, 0)

>>> parse("10-09-03")
datetime.datetime(2003, 10, 9, 0, 0)

>>> parse("10-09-03", yearfirst=True)
datetime.datetime(2010, 9, 3, 0, 0)

Other date separators are allowed:

>>> parse("2003.Sep.25")
datetime.datetime(2003, 9, 25, 0, 0)

>>> parse("2003/09/25")
datetime.datetime(2003, 9, 25, 0, 0)

Even with spaces:

>>> parse("2003 Sep 25")
datetime.datetime(2003, 9, 25, 0, 0)

>>> parse("2003 09 25")
datetime.datetime(2003, 9, 25, 0, 0)

Hours with letters work:

>>> parse("10h36m28.5s", default=DEFAULT)
datetime.datetime(2003, 9, 25, 10, 36, 28, 500000)

>>> parse("01s02h03m", default=DEFAULT)
datetime.datetime(2003, 9, 25, 2, 3, 1)

>>> parse("01h02m03", default=DEFAULT)
datetime.datetime(2003, 9, 3, 1, 2)

>>> parse("01h02", default=DEFAULT)
datetime.datetime(2003, 9, 2, 1, 0)

>>> parse("01h02s", default=DEFAULT)
datetime.datetime(2003, 9, 25, 1, 0, 2)

With AM/PM:

>>> parse("10h am", default=DEFAULT)
datetime.datetime(2003, 9, 25, 10, 0)

>>> parse("10pm", default=DEFAULT)
datetime.datetime(2003, 9, 25, 22, 0)

>>> parse("12:00am", default=DEFAULT)
datetime.datetime(2003, 9, 25, 0, 0)

>>> parse("12pm", default=DEFAULT)
datetime.datetime(2003, 9, 25, 12, 0)

Some special treating for pertain relations:

>>> parse("Sep 03", default=DEFAULT)
datetime.datetime(2003, 9, 3, 0, 0)

>>> parse("Sep of 03", default=DEFAULT)
datetime.datetime(2003, 9, 25, 0, 0)

Fuzzy parsing:

>>> s = "Today is 25 of September of 2003, exactly " \
...     "at 10:49:41 with timezone -03:00."
>>> parse(s, fuzzy=True)
datetime.datetime(2003, 9, 25, 10, 49, 41,
                  tzinfo=tzoffset(None, -10800))

Other random formats:

>>> parse("Wed, July 10, '96")
datetime.datetime(1996, 7, 10, 0, 0)

>>> parse("1996.07.10 AD at 15:08:56 PDT", ignoretz=True)
datetime.datetime(1996, 7, 10, 15, 8, 56)

>>> parse("Tuesday, April 12, 1952 AD 3:30:42pm PST", ignoretz=True)
datetime.datetime(1952, 4, 12, 15, 30, 42)

>>> parse("November 5, 1994, 8:15:30 am EST", ignoretz=True)
datetime.datetime(1994, 11, 5, 8, 15, 30)

>>> parse("3rd of May 2001")
datetime.datetime(2001, 5, 3, 0, 0)

>>> parse("5:50 A.M. on June 13, 1990")
datetime.datetime(1990, 6, 13, 5, 50)

easter

This module offers a generic easter computing method for any given year, using Western, Orthodox or Julian algorithms.

easter() function

This method was ported from the work done by GM Arts, on top of the algorithm by Claus Tondering, which was based in part on the algorithm of Ouding (1940), as quoted in "Explanatory Supplement to the Astronomical Almanac", P. Kenneth Seidelmann, editor.

This algorithm implements three different easter calculation methods:

Original calculation in Julian calendar, valid in dates after 326 AD
Original method, with date converted to Gregorian calendar, valid in years 1583 to 4099
Revised method, in Gregorian calendar, valid in years 1583 to 4099 as well

These methods are represented by the constants:

EASTER_JULIAN   = 1
EASTER_ORTHODOX = 2
EASTER_WESTERN  = 3

The default method is method 3.

tz

This module offers timezone implementations subclassing the abstract datetime.tzinfo type. There are classes to handle tzfile format files (usually are in /etc/localtime, /usr/share/zoneinfo, etc), TZ environment string (in all known formats), given ranges (with help from relative deltas), local machine timezone, fixed offset timezone, and UTC timezone.

tzutc type

This type implements a basic UTC timezone. The constructor of this type accepts no parameters.

tzutc examples

>>> from datetime import *
>>> from dateutil.tz import *

>>> datetime.now()
datetime.datetime(2003, 9, 27, 9, 40, 1, 521290)

>>> datetime.now(tzutc())
datetime.datetime(2003, 9, 27, 12, 40, 12, 156379, tzinfo=tzutc())

>>> datetime.now(tzutc()).tzname()
'UTC'

tzoffset type

This type implements a fixed offset timezone, with no support to daylight saving times. Here is the prototype of the type constructor:

tzoffset(name, offset)

The name parameter may be optionally set to None, and offset must be given in seconds.

tzoffset examples

>>> from datetime import *
>>> from dateutil.tz import *

>>> datetime.now(tzoffset("BRST", -10800))
datetime.datetime(2003, 9, 27, 9, 52, 43, 624904,
                  tzinfo=tzinfo=tzoffset('BRST', -10800))

>>> datetime.now(tzoffset("BRST", -10800)).tzname()
'BRST'

>>> datetime.now(tzoffset("BRST", -10800)).astimezone(tzutc())
datetime.datetime(2003, 9, 27, 12, 53, 11, 446419,
                  tzinfo=tzutc())

tzlocal type

This type implements timezone settings as known by the operating system. The constructor of this type accepts no parameters.

tzlocal examples

>>> from datetime import *
>>> from dateutil.tz import *

>>> datetime.now(tzlocal())
datetime.datetime(2003, 9, 27, 10, 1, 43, 673605,
                  tzinfo=tzlocal())

>>> datetime.now(tzlocal()).tzname()
'BRST'

>>> datetime.now(tzlocal()).astimezone(tzoffset(None, 0))
datetime.datetime(2003, 9, 27, 13, 3, 0, 11493,
                  tzinfo=tzoffset(None, 0))

tzstr type

This type implements timezone settings extracted from a string in known TZ environment variable formats. Here is the prototype of the constructor:

tzstr(str)

tzstr examples

Here are examples of the recognized formats:

EST5EDT
EST5EDT,4,0,6,7200,10,0,26,7200,3600
EST5EDT,4,1,0,7200,10,-1,0,7200,3600
EST5EDT4,M4.1.0/02:00:00,M10-5-0/02:00
EST5EDT4,95/02:00:00,298/02:00
EST5EDT4,J96/02:00:00,J299/02:00

Notice that if daylight information is not present, but a daylight abbreviation was provided, tzstr will follow the convention of using the first sunday of April to start daylight saving, and the last sunday of October to end it. If start or end time is not present, 2AM will be used, and if the daylight offset is not present, the standard offset plus one hour will be used. This convention is the same as used in the GNU libc.

This also means that some of the above examples are exactly equivalent, and all of these examples are equivalent in the year of 2003.

Here is the example mentioned in the time module documentation.

>>> os.environ['TZ'] = 'EST+05EDT,M4.1.0,M10.5.0'
>>> time.tzset()
>>> time.strftime('%X %x %Z')
'02:07:36 05/08/03 EDT'
>>> os.environ['TZ'] = 'AEST-10AEDT-11,M10.5.0,M3.5.0'
>>> time.tzset()
>>> time.strftime('%X %x %Z')
'16:08:12 05/08/03 AEST'

And here is an example showing the same information using tzstr, without touching system settings.

>>> tz1 = tzstr('EST+05EDT,M4.1.0,M10.5.0')
>>> tz2 = tzstr('AEST-10AEDT-11,M10.5.0,M3.5.0')
>>> dt = datetime(2003, 5, 8, 2, 7, 36, tzinfo=tz1)
>>> dt.strftime('%X %x %Z')
'02:07:36 05/08/03 EDT'
>>> dt.astimezone(tz2).strftime('%X %x %Z')
'16:07:36 05/08/03 AEST'

Are these really equivalent?

>>> tzstr('EST5EDT') == tzstr('EST5EDT,4,1,0,7200,10,-1,0,7200,3600')
True

Check the daylight limit.

>>> datetime(2003, 4, 6, 1, 59, tzinfo=tz).tzname()
'EST'
>>> datetime(2003, 4, 6, 2, 00, tzinfo=tz).tzname()
'EDT'
>>> datetime(2003, 10, 26, 0, 59, tzinfo=tz).tzname()
'EDT'
>>> datetime(2003, 10, 26, 1, 00, tzinfo=tz).tzname()
'EST'

tzrange type

This type offers the same functionality as the tzstr type, but instead of timezone strings, information is passed using relativedeltas which are applied to a datetime set to the first day of the year. Here is the prototype of this type's constructor:

tzrange(stdabbr, stdoffset=None, dstabbr=None, dstoffset=None,
        start=None, end=None):

Offsets must be given in seconds. Information not provided will be set to the defaults, as explained in the tzstr section above.

tzrange examples

>>> tzstr('EST5EDT') == tzrange("EST", -18000, "EDT")
True

>>> from dateutil.relativedelta import *
>>> range1 = tzrange("EST", -18000, "EDT")
>>> range2 = tzrange("EST", -18000, "EDT", -14400,
...                  relativedelta(hours=+2, month=4, day=1,
                                   weekday=SU(+1)),
...                  relativedelta(hours=+1, month=10, day=31,
                                   weekday=SU(-1)))
>>> tzstr('EST5EDT') == range1 == range2
True

Notice a minor detail in the last example: while the DST should end at 2AM, the delta will catch 1AM. That's because the daylight saving time should end at 2AM standard time (the difference between STD and DST is 1h in the given example) instead of the DST time. That's how the tzinfo subtypes should deal with the extra hour that happens when going back to the standard time. Check tzinfo documentation for more information.

tzfile type

This type allows one to use tzfile(5) format timezone files to extract current and historical zone information. Here is the type constructor prototype:

tzfile(fileobj)

Where fileobj is either a filename or a file-like object with a read() method.

tzfile examples

>>> tz = tzfile("/etc/localtime")
>>> datetime.now(tz)
datetime.datetime(2003, 9, 27, 12, 3, 48, 392138,
                  tzinfo=tzfile('/etc/localtime'))

>>> datetime.now(tz).astimezone(tzutc())
datetime.datetime(2003, 9, 27, 15, 3, 53, 70863,
                  tzinfo=tzutc())

>>> datetime.now(tz).tzname()
'BRST'
>>> datetime(2003, 1, 1, tzinfo=tz).tzname()
'BRDT'

Check the daylight limit.

>>> tz = tzfile('/usr/share/zoneinfo/EST5EDT')
>>> datetime(2003, 4, 6, 1, 59, tzinfo=tz).tzname()
'EST'
>>> datetime(2003, 4, 6, 2, 00, tzinfo=tz).tzname()
'EDT'
>>> datetime(2003, 10, 26, 0, 59, tzinfo=tz).tzname()
'EDT'
>>> datetime(2003, 10, 26, 1, 00, tzinfo=tz).tzname()
'EST'

tzical type

This type is able to parse iCalendar style VTIMEZONE sessions into a Python timezone object. The constuctor prototype is:

tzical(fileobj)

Where fileobj is either a filename or a file-like object with a read() method.

tzical methods

tzical.get(tzid=None): Since a single iCalendar file may contain more than one timezone, you must ask for the timezone you want with this method. If there's more than one timezone in the parsed file, you'll need to pass the
tzid parameter. Otherwise, leaving it empty will yield the only available timezone.

tzical examples

Here is a sample file extracted from the RFC. This file defines the EST5EDT timezone, and will be used in the following example.

BEGIN:VTIMEZONE
TZID:US-Eastern
LAST-MODIFIED:19870101T000000Z
TZURL:http://zones.stds_r_us.net/tz/US-Eastern
BEGIN:STANDARD
DTSTART:19671029T020000
RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10
TZOFFSETFROM:-0400
TZOFFSETTO:-0500
TZNAME:EST
END:STANDARD
BEGIN:DAYLIGHT
DTSTART:19870405T020000
RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=4
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
TZNAME:EDT
END:DAYLIGHT
END:VTIMEZONE

And here is an example exploring a tzical type:

>>> from dateutil.tz import *; from datetime import *

>>> tz = tzical('EST5EDT.ics')
>>> tz.keys()
['US-Eastern']

>>> est = tz.get('US-Eastern')
>>> est
<tzicalvtz 'US-Eastern'>

>>> datetime.now(est)
datetime.datetime(2003, 10, 6, 19, 44, 18, 667987,
                  tzinfo=<tzicalvtz 'US-Eastern'>)

>>> est == tz.get()
True

Let's check the daylight ranges, as usual:

>>> datetime(2003, 4, 6, 1, 59, tzinfo=est).tzname()
'EST'
>>> datetime(2003, 4, 6, 2, 00, tzinfo=est).tzname()
'EDT'

>>> datetime(2003, 10, 26, 0, 59, tzinfo=est).tzname()
'EDT'
>>> datetime(2003, 10, 26, 1, 00, tzinfo=est).tzname()
'EST'

tzwin type

This type offers access to internal registry-based Windows timezones. The constuctor prototype is:

tzwin(name)

Where name is the timezone name. There's a static tzwin.list() method to check the available names,

tzwin methods

tzwin.display(): This method returns the timezone extended name.
tzwin.list(): This static method lists all available timezone names.

tzwin examples

>>> tz = tzwin("E. South America Standard Time")

tzwinlocal type

This type offers access to internal registry-based Windows timezones. The constructor accepts no parameters, so the prototype is:

tzwinlocal()

tzwinlocal methods

tzwinlocal.display(): This method returns the timezone extended name, and returns
None if one is not available.

tzwinlocal examples

>>> tz = tzwinlocal()

gettz() function

This function is a helper that will try its best to get the right timezone for your environment, or for the given string. The prototype is as follows:

gettz(name=None)

If given, the parameter may be a filename, a path relative to the base of the timezone information path (the base could be /usr/share/zoneinfo, for example), a string timezone specification, or a timezone abbreviation. If name is not given, and the TZ environment variable is set, it's used instead. If the parameter is not given, and TZ is not set, the default tzfile paths will be tried. Then, if no timezone information is found, an internal compiled database of timezones is used. When running on Windows, the internal registry-based Windows timezones are also considered.

Example:

>>> from dateutil.tz import *
>>> gettz()
tzfile('/etc/localtime')

>>> gettz("America/Sao Paulo")
tzfile('/usr/share/zoneinfo/America/Sao_Paulo')

>>> gettz("EST5EDT")
tzfile('/usr/share/zoneinfo/EST5EDT')

>>> gettz("EST5")
tzstr('EST5')

>>> gettz('BRST')
tzlocal()

>>> os.environ["TZ"] = "America/Sao Paulo"
>>> gettz()
tzfile('/usr/share/zoneinfo/America/Sao_Paulo')

>>> os.environ["TZ"] = "BRST"
>>> gettz()
tzlocal()

>>> gettz("Unavailable")
>>>

zoneinfo

This module provides direct access to the internal compiled database of timezones. The timezone data and the compiling tools are obtained from the following project:

http://www.twinsun.com/tz/tz-link.htm

gettz() function

This function will try to retrieve the given timezone information from the internal compiled database, and will cache its results.

Example:

>>> from dateutil import zoneinfo
>>> zoneinfo.gettz("Brazil/East")
tzfile('Brazil/East')

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