R/pp.stable.R

In lmomco: L-Moments, Censored L-Moments, Trimmed L-Moments, L-Comoments, and Many Distributions

"pp.stable" <-
function(x, A=NULL, B=NULL, a=0, sort=TRUE, ties.method="first",
            u=NULL, ...) {

   if(! is.null(u)) {
     if(sort) {
       return((2/pi) * asin( sqrt(sort(u)) ))
     } else {
       return((2/pi) * asin( sqrt(     u ) ))
     }
   }

   if(! is.null(a)) {
      if(a < 0 | a > 0.50) {
         warning("Plotting position parameter a is invalid, not in [0,0.5]")
         return()
      }
      A <-      -a
      B <- 1 - 2*a
   } else {
     if(is.null(A)) {
       warnings("Plotting position parameter A is NULL")
       return(NULL)
     }
     if(is.null(B)) {
       warnings("Plotting position parameter B is NULL")
       return(NULL)
     }
     if(A <= -1) {
       warnings("Plotting position parameter A <= -1, invalid")
       return(NULL)
     }
     if(B <= -1) {
       warnings("Plotting position parameter B <= -1, invalid")
       return(NULL)
     }
     if(A >= B) {
       warnings("Plotting position parameters B < A, invalid")
       return(NULL)
     }
   }

   denom <- length(x) + B
   ranks <- rank(x, ties.method=ties.method)

   if(sort) {
      return( (2/pi) * asin(sqrt( (sort(ranks) + A) / denom) ) )
   } else {
      return( (2/pi) * asin(sqrt( (     ranks  + A) / denom) ) )
   }
}