R/Lmoments.R

In PRSim: Stochastic Simulation of Streamflow Time Series using Phase Randomization

Lmoments <- function (x) 
{
  camp <- sort(x)
  n <- length(camp)
  nn <- rep(n - 1, n)
  pp <- seq(0, n - 1)
  p1 <- pp/nn
  p2 <- p1 * (pp - 1)/(nn - 1)
  p3 <- p2 * (pp - 2)/(nn - 2)
  b0 <- sum(camp)/n
  b1 <- sum(p1 * camp)/n
  b2 <- sum(p2 * camp)/n
  b3 <- sum(p3 * camp)/n
  l1 <- b0
  l2 <- 2 * b1 - b0
  lcv <- 2 * b1/b0 - 1
  lca <- 2 * (3 * b2 - b0)/(2 * b1 - b0) - 3
  lkur <- 5 * (2 * (2 * b3 - 3 * b2) + b0)/(2 * b1 - b0) + 
    6
  Lmom <- c(l1, l2, lcv, lca, lkur)
  names(Lmom) <- c("l1", "l2", "lcv", "lca", 
                   "lkur")
  return(Lmom)
}