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.

class dateutil.rrule.rrule(freq, dtstart=None, interval=1, wkst=None, count=None, until=None, bysetpos=None, bymonth=None, bymonthday=None, byyearday=None, byeaster=None, byweekno=None, byweekday=None, byhour=None, byminute=None, bysecond=None, cache=False)[source]

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.

Note

Per RFC section 3.3.10, recurrence instances falling on invalid dates and times are ignored rather than coerced:

Recurrence rules may generate recurrence instances with an invalid date (e.g., February 30) or nonexistent local time (e.g., 1:30 AM on a day where the local time is moved forward by an hour at 1:00 AM). Such recurrence instances MUST be ignored and MUST NOT be counted as part of the recurrence set.

This can lead to possibly surprising behavior when, for example, the start date occurs at the end of the month:

>>> from dateutil.rrule import rrule, MONTHLY
>>> from datetime import datetime
>>> start_date = datetime(2014, 12, 31)
>>> list(rrule(freq=MONTHLY, count=4, dtstart=start_date))
... 
[datetime.datetime(2014, 12, 31, 0, 0),
 datetime.datetime(2015, 1, 31, 0, 0),
 datetime.datetime(2015, 3, 31, 0, 0),
 datetime.datetime(2015, 5, 31, 0, 0)]

Additionally, it supports the following keyword arguments:

Parameters:
  • 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.

    Note

    As of version 2.5.0, the use of the until keyword together with the count keyword is deprecated per RFC-2445 Sec. 4.3.10.

  • until

    If given, this must be a datetime instance, that will specify the limit of the recurrence. The last recurrence in the rule is the greatest datetime that is less than or equal to the value specified in the until parameter.

    Note

    As of version 2.5.0, the use of the until keyword together with the count keyword is deprecated per RFC-2445 Sec. 4.3.10.

  • 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.
class dateutil.rrule.rruleset(cache=False)[source]

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:

Parameters:cache – If True, caching of results will be enabled, improving performance of multiple queries considerably.
exdate(*args, **kwargs)[source]
exrule(*args, **kwargs)[source]
rdate(*args, **kwargs)[source]
rrule(*args, **kwargs)[source]