R/eqqplot.R

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

# empirical quantile-quantile plot; hacked from qqplot() in stats.
eqqplot <- function(x, y, plot.it = TRUE, xlab = deparse(substitute(x)),
                    ylab = deparse(substitute(y)), ...) {

  sx <- sort(x)
  sy <- sort(y)
  lenx <- length(sx)
  leny <- length(sy)
  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
  }
  if (plot.it) {
    plot(sx, sy, xlab = xlab, ylab = ylab, ...)
  }
  invisible(list(x = sx, y = sy))
}