R/qqsum.R

In DanRunfola/SimTests: MatchIt: Nonparametric Preprocessing for Parametric Casual Inference

## Function for QQ summary stats
qqsum <- function (x, y, standardize = FALSE){
  sx <- sort(x)
  sy <- sort(y)
  lenx <- length(sx)
  leny <- length(sy)
  if (standardize) {
    vals <- sort(unique(c(sx, sy)))
    sx <- ecdf(sx)
    sx <- sx(vals)
    sy <- ecdf(sy)
    sy <- sy(vals)
  }
  else {
    if (leny < lenx) 
      sx <- approx(1:lenx, sx, n = leny, method = "constant")$y
    if (leny > lenx) 
      sy <- approx(1:leny, sy, n = lenx, method = "constant")$y
  }
  dxy <- abs(sx-sy)
  meandiff <- mean(dxy)
  meddiff <- median(dxy)
  maxdiff <- max(dxy)
  invisible(list(meandiff=meandiff, meddiff=meddiff, maxdiff=maxdiff))
}