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.

Module Contents

Classes

weekday(self,wkday,n=None) This version of weekday does not allow n = 0.
rrulebase(self,cache=False)
rrule(self,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) That’s the base of the rrule operation. It accepts all the keywords
_iterinfo(self,rrule)
rruleset(self,cache=False) The rruleset type allows more complex recurrence setups, mixing
_rrulestr()

Functions

_invalidates_cache(f) Decorator for rruleset methods which may invalidate the
class weekday(wkday, n=None)

This version of weekday does not allow n = 0.

__init__(wkday, n=None)
_invalidates_cache(f)

Decorator for rruleset methods which may invalidate the cached length.

class rrulebase(cache=False)
__init__(cache=False)
__iter__()
_invalidate_cache()
_iter_cached()
__getitem__(item)
__contains__(item)
count()

Returns the number of recurrences in this set. It will have go trough the whole recurrence, if this hasn’t been done before.

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.

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.

xafter(dt, count=None, inc=False)

Generator which yields up to count recurrences after the given datetime instance, equivalent to after.

Parameters:
  • dt – The datetime at which to start generating recurrences.
  • count – The maximum number of recurrences to generate. If None (default), dates are generated until the recurrence rule is exhausted.
  • inc – If dt is an instance of the rule and inc is True, it is included in the output.
Yields:

Yields a sequence of datetime objects.

between(after, before, inc=False, count=1)

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.

class 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)

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:
  • 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-5545 Sec. 3.3.10.

  • 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-5545 Sec. 3.3.10.

  • 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.
  • 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.
  • 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.
  • 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.
__init__(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)
__str__()

Output a string that would generate this RRULE if passed to rrulestr. This is mostly compatible with RFC5545, except for the dateutil-specific extension BYEASTER.

replace(**kwargs)

Return new rrule with same attributes except for those attributes given new values by whichever keyword arguments are specified.

_iter()
__construct_byset(start, byxxx, base)

If a BYXXX sequence is passed to the constructor at the same level as FREQ (e.g. FREQ=HOURLY,BYHOUR={2,4,7},INTERVAL=3), there are some specifications which cannot be reached given some starting conditions.

This occurs whenever the interval is not coprime with the base of a given unit and the difference between the starting position and the ending position is not coprime with the greatest common denominator between the interval and the base. For example, with a FREQ of hourly starting at 17:00 and an interval of 4, the only valid values for BYHOUR would be {21, 1, 5, 9, 13, 17}, because 4 and 24 are not coprime.

Parameters:
  • start – Specifies the starting position.
  • byxxx – An iterable containing the list of allowed values.
  • base – The largest allowable value for the specified frequency (e.g. 24 hours, 60 minutes).

This does not preserve the type of the iterable, returning a set, since the values should be unique and the order is irrelevant, this will speed up later lookups.

In the event of an empty set, raises a :exception:`ValueError`, as this results in an empty rrule.

__mod_distance(value, byxxx, base)

Calculates the next value in a sequence where the FREQ parameter is specified along with a BYXXX parameter at the same “level” (e.g. HOURLY specified with BYHOUR).

Parameters:
  • value – The old value of the component.
  • byxxx – The BYXXX set, which should have been generated by rrule._construct_byset, or something else which checks that a valid rule is present.
  • base – The largest allowable value for the specified frequency (e.g. 24 hours, 60 minutes).

If a valid value is not found after base iterations (the maximum number before the sequence would start to repeat), this raises a :exception:`ValueError`, as no valid values were found.

This returns a tuple of divmod(n*interval, base), where n is the smallest number of interval repetitions until the next specified value in byxxx is found.

class _iterinfo(rrule)
__init__(rrule)
rebuild(year, month)
ydayset(year, month, day)
mdayset(year, month, day)
wdayset(year, month, day)
ddayset(year, month, day)
htimeset(hour, minute, second)
mtimeset(hour, minute, second)
stimeset(hour, minute, second)
class rruleset(cache=False)

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.
class _genitem(genlist, gen)
__init__(genlist, gen)
__next__()
__lt__(other)
__gt__(other)
__eq__(other)
__ne__(other)
__init__(cache=False)
rrule(rrule)

Include the given rrule instance in the recurrence set generation.

rdate(rdate)

Include the given datetime instance in the recurrence set generation.

exrule(exrule)

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.

exdate(exdate)

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.

_iter()
class _rrulestr
_handle_int(rrkwargs, name, value, **kwargs)
_handle_int_list(rrkwargs, name, value, **kwargs)
_handle_FREQ(rrkwargs, name, value, **kwargs)
_handle_UNTIL(rrkwargs, name, value, **kwargs)
_handle_WKST(rrkwargs, name, value, **kwargs)
_handle_BYWEEKDAY(rrkwargs, name, value, **kwargs)

Two ways to specify this: +1MO or MO(+1)

_parse_rfc_rrule(line, dtstart=None, cache=False, ignoretz=False, tzinfos=None)
_parse_rfc(s, dtstart=None, cache=False, unfold=False, forceset=False, compatible=False, ignoretz=False, tzids=None, tzinfos=None)
__call__(s, **kwargs)