almanac (version 0.1.1)

recur_on_wday: Recur on a day of the week

Description

• recur_on_wday() recurs on a specific day of the week.

• recur_on_weekends() and recur_on_weekdays() are helpers for recurring on weekends and weekdays.

Usage

recur_on_wday(x, wday, nth = NULL)
recur_on_weekdays(x)
recur_on_weekends(x)

Value

An updated rrule.

Arguments

x

[rrule]

A recurrence rule.

wday

[integer / character]

Days of the week to recur on. Integer values must be from 1 to 7, with 1 = Monday and 7 = Sunday. This is also allowed to be a full weekday string like "Tuesday", or an abbreviation like "Tues".

nth

[integer / NULL]

Limit to the n-th occurrence of the wday in the base frequency. For example, in a monthly frequency, using nth = -1 would limit to the last wday in the month. The default of NULL chooses all occurrences.

Details

Multiple week day values are allowed, and nth will be applied to all of them. If you want to apply different nth values to different days of the week, call recur_on_wday() twice with different wday values.

It is particularly important to pay attention to the since date when using weekly rules. The day of the week to use comes from the since date, which, by default, is a Monday (1900-01-01).

Examples

# Using default `since` (1900-01-01, a Monday)
on_weekly_mondays <- weekly()

start <- "1999-01-01" # <- a Friday
end <- "1999-03-01"

# This finds the first Thursday, and then continues from there
alma_search(start, end, on_weekly_mondays)

# We start counting from a Friday here
on_weekly_fridays <- weekly(since = start)
alma_search(start, end, on_weekly_fridays)

# Alternatively, we could use `recur_on_wday()` and force a recurrence rule
# on Friday
on_wday_friday <- on_weekly_mondays %>% recur_on_wday("Friday")
alma_search(start, end, on_wday_friday)

# At monthly frequencies, you can use n-th values to look for particular
# week day events
on_first_friday_in_month <- monthly() %>% recur_on_wday("Fri", 1)
alma_search(start, end, on_first_friday_in_month)

# Negative values let you look from the back
on_last_friday_in_month <- monthly() %>% recur_on_wday("Fri", -1)
alma_search(start, end, on_last_friday_in_month)

# At yearly frequencies, this looks for the first sunday of the year
on_first_sunday_in_year <- yearly() %>% recur_on_wday("Sunday", 1)
alma_search(start, end, on_first_sunday_in_year)

# Last week day of the month
last_weekday_of_month <- monthly() %>%
  # Last occurrence of each weekday in the month
  recur_on_wday(c("Mon", "Tue", "Wed", "Thu", "Fri"), -1) %>%
  # Now choose the last one of those in each month
  recur_on_position(-1)

alma_search(start, end, last_weekday_of_month)