R/mojquarter.R

In moj-analytical-services/las_rap_code_library: Functions used for legal aid statistics publications and R Shiny apps

#' Convert dates to publication quarters
#'
#' Convert dates in "\%Y\%m\%d" format, i.e. with date formats in that order but
#' with arbitrary or no separators, to either calendar or financial quarters (i.e. where the financial
#' year starts in April in the UK).
#'
#' @param date A date in the form "\%Y\%m\%d".
#' @param type Either "c" or "f", to specify a calender quarter or a financial quarter.
#
#' @examples
#' mojquarter('2020-03-31', "f") # returns "2019q4"
#'
#' @return A character object.
#'
#' @export

mojquarter <- function(date, type = "c") {
  
  # Check that only one value is passed at a time and raise an error otherwise.
  
  if (length(date) > 1) {
    
    stop("Input date was a vector, but a single value is required")
    
    # Check that input is not null, and raise an error if it is
    
  } else if  (is.null(date)) {
    
    stop("Input date is NULL")
    
    # Check that input is not NA, and raise and error if it is
    
  } else if (is.na(date)) {
    
    stop("Input date is NA")
    
    # Check that the input is of character type, raise an error if not
    
  } else if (!is.character(date)) {
    
    stop("Input date is not in character format", call. = FALSE)
    
    # Check that type is either "c" or "f"
    
  } else if(!type %in% c("c", "f")) {
    
    stop("type must be either 'c' or 'f'")
    
  } else {
    
    # If checks of function pass, then run the main body of the function, and
    # return and output.
    
    
    # BODY --------------------------------------------------------------------
    
    if(type == "c") {
      
      date <- lubridate::ymd(date)
      year <- lubridate::year(date)
      return(paste0(year, "q", lubridate::quarter(date, fiscal_start = 1)))
      
    }
    
    else if(type == "f") {
      
      date <- lubridate::ceiling_date(lubridate::ymd(date), "months") - months(3) - lubridate::days(1)
      year <- lubridate::year(date)
      return(paste0(year, "q", lubridate::quarter(date)))
      
    }
    
  }
}