Return an integer of the number of weekdays in a month before or after a specified input date. Helpful for transit planning and NTD reporting when a sign-up period is in a split month. I.E. when the operator and route schedules change in the middle of a month and you must compute a weighted average based on the number of days within a signup per…

count_monthly_weekdays.R

## Returns an integer of the number of weekdays in a month before or after a specified input date
## Counts weekdays (M-F), weekends (Sat and Sun), Sat only or Sun only
## Borrowed code from @Thomas at link below:
## https://stackoverflow.com/questions/29252520/using-r-to-count-number-of-specific-days-in-a-specific-month

count_monthly_weekdays <- function(x, direction, weekday = "weekend", inclusive = FALSE){
  ## x is the date from which to calculate remaining weekend days
  ## direction is whether you count before or after input date x
  ## weekday is the weekdays to count (saturday, sunday, both, weekday)
  ## inclusive T/F is whether to include the input date x in the days remaining
  
  x <- as.Date(x)
  last_day_of_month <- ceiling_date(x, "month")-1
  first_day_of_month <- floor_date(x, "month")
  
  if(tolower(direction) == "after"){
    if(x == last_day_of_month & !inclusive){
      stop("Last day of month input. Specify inclusive = TRUE to include last day of month.")
    }
    if(!inclusive){x <- x + 1}
    d <- days_in_month(x)
    d2 <- x + (0:(d-day(x)))
  }
  
  if(tolower(direction) == "before"){
    if(x == first_day_of_month & !inclusive){
      stop("First day of month input. Specify inclusive = TRUE to include first day of month.")
    }
    if(!inclusive){x <- x - 1}
    d2 <- (first_day_of_month-1) + (day(first_day_of_month):day(x))
  }
  
  if(tolower(weekday) == "weekday"){
    return(sum(wday(d2) %in% c(2:6)))
  }  
  if(tolower(weekday) %in% c("saturday", "sat")){
    return(sum(wday(d2) %in% c(7)))
  }
  if(tolower(weekday) %in% c("sunday", "sun")){
    return(sum(wday(d2) %in% c(1)))
  }
  if(tolower(weekday) == "weekend"){
    return(sum(wday(d2) %in% c(1,7)))
  } 
}

count_monthly_weekdays('2022-02-01', 
                       direction = "before", 
                       weekday = "weekday", 
                       inclusive = TRUE)