R/easter_monday.R

In Glender/DutchDayDummies: R-package to create regression dummies for dutch holidays

#' Create dummies for Easter monday (In dutch: 'Tweede Paasdag')
#'
#' Create a dummy variable that takes the value 0 or 1 to indicate the
#' abscence or presence of Easter day. The day(s) before or after this holiday
#' can also be recoded by using the pre and post arguments. For example, if you also
#' want to recode the days after Easter monday, set
#' post argument to 1.
#'
#' @param dates A vector with dates in the format YYYY-MM-DD
#' @param pre non-negative int. To encode the days before the holiday dates.
#' @param post non-negative int. To encode the days after the holiday dates.
#' @return A dummy (binary vector)
#' @importFrom magrittr %>%
#' @export
#' @examples
#'df <- tibble::tibble(
#'dates = seq_days("2021-4-5", "2023-4-10"),
#'easter_mon = easter_monday(dates, post = 0)
#')
#'subset(df, easter_mon == 1)
easter_monday <- function(dates, pre=0, post=0){

  # find easter sunday (`2e paasdag`) day based on years
  years <- as.integer(unique(lubridate::year(dates)))
  easter_dates <- sapply(years, gauss_easter_algorithm_Cpp)

  # shift to easter monday instead of easter sunday
  easter_dates <- as.Date(easter_dates, format = "%Y-%m-%d") + 1
  easter_dates <- add_intervals(easter_dates, pre=pre, post=post)

  # add the holiday as dummies in your df
  output <- add_holiday_dummies(dates, easter_dates)
  return(output)
}