From 7ca8256b777f4085df7ce98f7d6f3d5581a2a132 Mon Sep 17 00:00:00 2001
From: Ellpeck <megamaximal@gmail.com>
Date: Fri, 17 Jan 2020 01:33:31 +0100
Subject: [PATCH] added a weight-based list randomness function

---
 MLEM/Extensions/RandomExtensions.cs | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/MLEM/Extensions/RandomExtensions.cs b/MLEM/Extensions/RandomExtensions.cs
index bc581e3..80be53f 100644
--- a/MLEM/Extensions/RandomExtensions.cs
+++ b/MLEM/Extensions/RandomExtensions.cs
@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Linq;
 
 namespace MLEM.Extensions {
     public static class RandomExtensions {
@@ -12,5 +13,17 @@ namespace MLEM.Extensions {
             return entries[random.Next(entries.Count)];
         }
 
+        public static T GetRandomWeightedEntry<T>(this Random random, IList<T> entries, Func<T, int> weightFunc) {
+            var totalWeight = entries.Sum(weightFunc);
+            var goalWeight = random.Next(totalWeight);
+            var currWeight = 0;
+            foreach (var entry in entries) {
+                currWeight += weightFunc(entry);
+                if (currWeight >= goalWeight)
+                    return entry;
+            }
+            throw new IndexOutOfRangeException();
+        }
+
     }
 }
\ No newline at end of file