R/wi_ci.R

In clidatajp: Data from Japan Meteorological Agency

#' Calculate warm index and cold index
#' 
#' @name wi
#' @references Kira, T. 1945. 
#'             A new classification of climate in eastern Asia as the basis for agricultural geography, 
#'             Hort. Inst. K,yoto Univ., Kyoto. (in Japanese)
#'             Warmth Index (WI) and Cold Index (CI) was proposed by Kira (1945), 
#'             which is known closely related to the distribution of vegetation. 
#'             Indices can are calculated by following equations.
#'             wi = sum (Ti - 5),
#'               where wi is Warm index, 
#'               Ti (celsius) is mean temprature of each month in a year when Ti > 5. 
#'             Indices can are calculated by following equations.
#'             wi = -sum (Ti - 5),
#'               where wi is Cold index, 
#'               when Ti < 5. 
#' @param x    A numeric vector
#' @return     A string vector of url links.
#' @examples
#' temp <- c(-7.8, -7.2, -2.4, 5.2, 11.7, 16.5, 20.5, 21.1, 15.6, 8.8, 2.0, -4.1)
#' wi(temp)
#' ci(temp)
#' wi <- sum(c(0, 0, 0, 0.2, 6.7, 11.5, 15.5, 16.1, 10.6, 3.8, 0, 0))
#' ci <- sum(c(12.8, 12.2, 7.4, 0, 0, 0, 0, 0, 0, 0, 3.0, 9.1))
#' 
#' @export
wi <- function(x){
  diff <- (x - 5)
  sum(diff[diff > 0])
}

#' @export
#' @rdname wi
ci <- function(x){
  diff <- (x - 5)
  sum(diff[diff < 0])
}