R/QiniArea.R

Defines functions QiniArea

Documented in QiniArea

QiniArea <- function(x){
  
  # Computes the area under the Qini curve.
  #
  # Args:
  #   x: a table that must be the output of PerformanceUplift() function.
  #
  # Returns:
  #   The Qini coefficient.
  
  if (!inherits(x, "PerformanceUplift"))
    stop("tools4uplift: object not of class PerformanceUplift")
  
  nb <- length(x$cum_per)
  sum <- x$inc_uplift[1]/2*x$T_n[1]/x$T_n[nb]
  for (i in 2:nb) {
    sum <- sum + (x$inc_uplift[i] + x$inc_uplift[i-1])/2*(x$T_n[i]/x$T_n[nb]-x$T_n[i-1]/x$T_n[nb])
  }
  
  return(sum-x$inc_uplift[nb]/2)
}

# END FUN

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tools4uplift documentation built on Sept. 25, 2019, 3:01 p.m.