Data update

Task/Entropy/OCaml/entropy-1.ml

@@ -0,0 +1,14 @@
+module CharMap = Map.Make(Char)
+
+let entropy s =
+  let count map c =
+    CharMap.update c (function Some n -> Some (n +. 1.) | None -> Some 1.) map
+  and calc _ n sum =
+    sum +. n *. Float.log2 n
+  in
+  let sum = CharMap.fold calc (String.fold_left count CharMap.empty s) 0.
+  and len = float (String.length s) in
+  Float.log2 len -. sum /. len
+
+let () =
+  entropy "1223334444" |> string_of_float |> print_endline