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(* Open Source License                                                       *)
(* Copyright (c) 2021 Nomadic Labs <contact@nomadic-labs.com>                *)
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let mean list =
  let count = ref 0 in
  let sum = ref 0. in
  List.iter
    (fun value ->
      incr count ;
      sum := !sum +. value)
    list ;
  !sum /. float !count

let median list =
  let sorted = List.sort Float.compare list |> Array.of_list in
  let count = Array.length sorted in
  if count > 0 then
    if count mod 2 = 0 then
      let i = count / 2 in
      (sorted.(i - 1) +. sorted.(i)) /. 2.
    else sorted.(count / 2)
  else invalid_arg "Long_test.median: empty list"

let stddev list =
  let list_mean = mean list in
  let squared_diffs =
    List.map
      (fun x ->
        let d = x -. list_mean in
        d *. d)
      list
  in
  sqrt (mean squared_diffs)