recur_on_week_of_year {almanac}

Recur on a week of the year

Description

recur_on_week_of_year() recurs on a specific week of the year.

Usage

recur_on_week_of_year(x, week)

Arguments

x

⁠[rrule]⁠

A recurrence rule.

week

⁠[integer]⁠

Weeks of the year to recur on. Integer values must be between ⁠[1, 53]⁠ or ⁠[-53, -1]⁠.

Details

Weekly rules are implemented according to the ISO-8601 standard. This requires that the first week of a year is the first one containing at least 4 days of the new year. Additionally, the week will start on the week day specified by recur_with_week_start(), which defaults to Monday.

Value

An updated rrule.

Examples

# Weekly rules are a bit tricky because they are implemented to comply
# with ISO-8601 standards, which require that the first week of the year
# is when there are at least 4 days in that year, and the week starts on
# the week day specified by `recur_with_week_start()` (Monday by default).
on_first_week <- yearly() %>% recur_on_week_of_year(1)

# In 2017:
# - Look at dates 1-4
# - 2017-01-02 is a Monday, so start the first week here
alma_search("2017-01-01", "2017-01-25", on_first_week)

# In 2015:
# - Look at dates 1-4
# - None of these are Monday, so the start of the week is
#   in the previous year
# - Look at 2014 and find the last Monday, 2014-12-29. This is the start of
#   the first week in 2015.
alma_search("2014-12-25", "2015-01-25", on_first_week)

# Say we want the start of the week to be Sunday instead of Monday!

# In 2015:
# - Look at dates 1-4
# - 2015-01-04 is a Sunday, so start the first week here
on_first_week_sun <- yearly() %>%
  recur_on_week_of_year(1) %>%
  recur_with_week_start("Sunday")

alma_search("2014-12-25", "2015-01-25", on_first_week_sun)