From 071bea1a8d27e953fee1f41f8fa7a7cb4ea9c2a0 Mon Sep 17 00:00:00 2001
From: Pitchaya Boonsarngsuk <2285135b@student.gla.ac.uk>
Date: Mon, 5 Feb 2018 10:56:03 +0000
Subject: [PATCH] Optimize subset randomizer for interp

---
 src/interpolation/helpers.js | 25 ++++++++++++++++++++-----
 1 file changed, 20 insertions(+), 5 deletions(-)

diff --git a/src/interpolation/helpers.js b/src/interpolation/helpers.js
index 92c6614..2bf620c 100644
--- a/src/interpolation/helpers.js
+++ b/src/interpolation/helpers.js
@@ -10,12 +10,19 @@
  */
 export function takeSampleFrom(sourceList, amount) {
   let randElements = [],
-      max = sourceList.length;
+      max = sourceList.length,
+      swap = false;
 
   if (amount >= max) {
     return {sample: sourceList, remainder: {}};
   }
 
+  // If picking more than half of the entire set, random to pick the remainder instead
+  if (amount > Math.ceil(max/2)){
+    amount = max - amount;
+    swap = true;
+  }
+
   for (let i = 0; i < amount; ++i) {
     let rand = sourceList[Math.floor((Math.random() * max))];
     // Re-random until suitable value is found.
@@ -28,10 +35,18 @@ export function takeSampleFrom(sourceList, amount) {
     return !randElements.includes(obj);
   });
 
-  return {
-    sample: randElements,
-    remainder: remainder
-  };
+  if(swap) {
+    return {
+      sample: remainder,
+      remainder: randElements
+    };
+  }
+  else {
+    return {
+      sample: randElements,
+      remainder: remainder
+    };
+  }
 }
 
 /**