# lastWeekday: Functions for Computing Days of the Week In datetimeutils: Utilities for Dates and Times

## Description

Functions for computing a specifed day-of-week, such as ‘the last Friday of October 2015’.

## Usage

 ```1 2 3``` ```last_weekday(weekday, x, shift = 0L, period = "month", before, inclusive = TRUE) nth_weekday(weekday, x, n = 1L) ```

## Arguments

 `x` a vector of class `Date` (but only the `YYYY-MM` part is relevant) `shift` a vector of integers `weekday` an integer (`1` is Monday, `2` is Tuesday, and so on) `period` character. Currently ignored. `before` a `Date`. See also `inclusive`. `inclusive` logical. Is `before` meant is ‘before but including’? `n` an integer

## Details

`last_weekday` computes the last day-of-the-week (specified as an integer 0 to 6, with Sunday being 0) in a given month, e.g. ‘the last Friday’. `shift` moves forward (when positive) or backward (when negative) by one week; see Examples.

`nth_weekday` gives the n-th day-of-the-week (specified as an integer 0 to 6, with Sunday being 0) of a given month, e.g. ‘the second Monday’.

`Date`

Enrico Schumann

## References

B.D. Ripley and K. Hornik. Date-Time Classes. R-News, 1(2):8–12, 2001.

`DateTimeClasses`
 ```1 2 3 4 5 6 7``` ```## GOAL: find the third Friday in March 2013 ## SOLUTION: find the last Friday in February 2013 and ## shift forward by 3 weeks last_weekday(5, as.Date("2013-02-01"), shift = 3) ## ... or much simpler nth_weekday(5, as.Date("2013-03-01"), 3) ```