YAPC::EU 2018 Glasgow Update!

Task/Entropy/Swift/entropy.swift

@@ -0,0 +1,14 @@
+import Foundation
+
+func entropy(of x: String) -> Double {
+  return x
+    .reduce(into: [String: Int](), {cur, char in
+      cur[String(char), default: 0] += 1
+    })
+    .values
+    .map({i in Double(i) / Double(x.count) } as (Int) -> Double)
+    .map({p in -p * log2(p) } as (Double) -> Double)
+    .reduce(0.0, +)
+}
+
+print(entropy(of: "1223334444"))