Creating composite score data

[hadley]

I think this could be simplified quite a bit with a couple of functions like

rescale01 <- function(x) {
  rng <- range(x, na.rm = TRUE)
  (x - rng[1]) / (rng[2] - rng[1])
}

composite_score <- function(x, wt) {
   x <- rescale01(x)
   x <- x[!is.na(x)]

  mean(wt * x)
}

(I think that's what you're doing, but I'm not absolutely sure)

[hadley]

Similarly, when computing indexes, it would be a good idea to reduce some of the duplication with a function.

[aloy]

I pared down the code using your suggestion for rescale01 along with the weighted.mean function.