diff --git a/src/interpolation/helpers.js b/src/interpolation/helpers.js
index 38d9930..3c3e74a 100644
--- a/src/interpolation/helpers.js
+++ b/src/interpolation/helpers.js
@@ -1,18 +1,31 @@
-export function takeSampleFrom(nodes, amount) {
+/**
+ * Pick a certain amount of unique objects from sourceList.
+ * If the amount requested is more than total number of objects in sourceList,
+ * only everything available in sourceList and nothing more will be picked.
+ * @param  {list} sourceList
+ * @param  {number} amount
+ * @return {object} - {sample: list, remainder: list}
+                      sample is the list of selected objects while
+                      remainder is the list of those unselected.
+ */
+export function takeSampleFrom(sourceList, amount) {
   let randElements = [],
-      max = nodes.length;
+      max = sourceList.length;
 
-  for (var i = 0; i < amount; ++i) {
-    var rand = nodes[Math.floor((Math.random() * max))];
-    // If the rand is already in random list or in exclude list
-    // ignore it and get a new value.
+  if (amount <= max) {
+    return {sample: sourceList, remainder: {}};
+  }
+
+  for (let i = 0; i < amount; ++i) {
+    let rand = sourceList[Math.floor((Math.random() * max))];
+    // Re-random until suitable value is found.
     while (randElements.includes(rand)) {
-      rand = nodes[Math.floor((Math.random() * max))];
+      rand = sourceList[Math.floor((Math.random() * max))];
     }
     randElements.push(rand);
   }
-  var remainder = nodes.filter(function (node) {
-    return !randElements.includes(node);
+  var remainder = sourceList.filter(function (obj) {
+    return !randElements.includes(obj);
   });
 
   return {
@@ -21,8 +34,15 @@ export function takeSampleFrom(nodes, amount) {
   };
 }
 
-// With a circle radius r, and center at (h,k),
-// Find the coordinate of a point at angle degree
+/**
+ * With a circle radius r, and center at (h,k),
+ * Find the coordinate of a point at angle degrees
+ * @param {number} h
+ * @param {number} k
+ * @param {number} angle
+ * @param {number} r
+ * @return {object} - coordinate {x: number, y: number} of the point
+ */
 export function pointOnCircle(h, k, angle, r) {
   let x = h + r*Math.cos(toRadians(angle));
   let y = k + r*Math.sin(toRadians(angle));
@@ -37,6 +57,17 @@ function toRadians(degrees) {
   return degrees * (Math.PI / 180);
 }
 
+/**
+ * Find the sum of ( difference between high and low dimensional distance )
+ * between a node and each of the samples. The high dimensional distances are
+ * precalculated and stored in realDistances.
+ * @param {object} node        - a single node, must have x and y properties
+ * @param {list} samples       - list of other node objects to compare against
+ * @param {list} realDistances - list of number distances between the node to
+                                 each of the samples. Index must correspond to
+                                 that of samples.
+ * @return {number} - Sum of distances differences
+ */
 export function sumDistError(node, samples, realDistances) {
   let total = 0.0;
   for (let i = 0; i < samples.length; i++) {