R/foos.R

In danmrc/recessionR: Plot NBER recessions shade in any graphic

#' Loads the dates of begining and ending of recessions acording to NBER
#'
#' @param periodicity What is the periodicity of data used. Only accepts (q)uartely or (m)onthly. You can use the whole word or only the first letter
#' @return An matrix with two columns: the first is the beggining of the recession according to NBER and the second column the end
#' @note The diference between this command and \code{\link{nber_load_ggplot}} is that this one \code{ts} convention, i.e. year.fraction, while \code{\link{nber_load_ggplot}} uses the data that are human readable
#' @seealso \code{\link{nber_load_ggplot}}
nber_load <- function(periodicity){
  if(periodicity == "q"|periodicity == "quartely"){
    dados <- recessions_quartely
  } else if(periodicity == "m"|periodicity == "monthly"){
    dados <- recessions_monthly
  } else{
    stop("Periodicity must be quarters of months")
  }
  return(dados)
}

#' Plot using base plot
#'
#'@param periodicity What is the periodicity of data used. Only accepts (q)uartely or (m)onthly. You can use the whole word or only the first letter
#'@param ytop,ybottom Controls the upper and lower limits of the shading. The default should be enough for most data
#'@param alpha Controls the transparency of the shade. Should be a number between 0 and 1
#'@return If there is a time series already plot, it should shade the back. Otherwise, it returns an error.
#'@examples
#' x <- rnorm(100)
#' x <- ts(x,start = c(1900,01),freq=4)
#' plot(x)
#' plot_recession("q")
plot_recession <- function(periodicity, ytop = 700, ybottom = -700,alpha = 0.3){
  dados <- nber_load(periodicity = periodicity)
  rect(xleft = dados[,1],xright = dados[,2], ytop = ytop,ybottom = ybottom, col = rgb(0,0,0,alpha = alpha), border = rgb(0,0,0,alpha = alpha))
}