From 5f9225538c24d4d630fc7df0e690776a37f8c227 Mon Sep 17 00:00:00 2001
From: NunoSempere <nuno.sempere@protonmail.com>
Date: Mon, 11 Apr 2022 14:39:29 -0400
Subject: [PATCH] tweak: add coefficient of variation

---
 .vscode/settings.json |  3 +++
 lib/findPaths.js      |  5 +++++
 lib/utils.js          | 23 +++++++++++++++++++++++
 3 files changed, 31 insertions(+)
 create mode 100644 .vscode/settings.json

diff --git a/.vscode/settings.json b/.vscode/settings.json
new file mode 100644
index 0000000..a4df25f
--- /dev/null
+++ b/.vscode/settings.json
@@ -0,0 +1,3 @@
+{
+  "cSpell.words": ["Stdev"]
+}
diff --git a/lib/findPaths.js b/lib/findPaths.js
index 7f20757..947397f 100644
--- a/lib/findPaths.js
+++ b/lib/findPaths.js
@@ -5,6 +5,7 @@ import {
   formatLargeOrSmall,
   avg,
   hackyGeomMean,
+  getCoefficientOfVariation,
 } from "../lib/utils.js";
 
 /* Functions */
@@ -301,6 +302,7 @@ export function CreateTable({ tableRows }) {
             <th>Possible relative values</th>
             <th> &nbsp;&nbsp;&nbsp;</th>
             <th>geomMean(relative values)</th>
+            <th>Coefficient of variation</th>
           </tr>
         </thead>
         <tbody>
@@ -317,6 +319,9 @@ export function CreateTable({ tableRows }) {
               <td className="">
                 {formatLargeOrSmall(hackyGeomMean(row.distances))}
               </td>
+              <td className="">
+                {formatLargeOrSmall(getCoefficientOfVariation(row.distances))}
+              </td>
             </tr>
           ))}
         </tbody>
diff --git a/lib/utils.js b/lib/utils.js
index 5d48779..db131e8 100644
--- a/lib/utils.js
+++ b/lib/utils.js
@@ -117,3 +117,26 @@ export function conservativeNumMergeSortSteps(n) {
 // export const geomMean = (arr) => arr.reduce((a, b) => a * b, 1); // ^ (1 / arr.length); // didn't work so well for low numbers.
 
 export const increasingList = (n) => Array.from(Array(n).keys());
+
+function getStdev(arr) {
+  if (Array.isArray(arr) && arr.length > 0) {
+    const n = arr.length;
+    const mean = arr.reduce((a, b) => a + b) / n;
+    return Math.sqrt(
+      arr.map((x) => Math.pow(x - mean, 2)).reduce((a, b) => a + b) / n
+    );
+  } else {
+    return 0;
+  }
+}
+
+export const getCoefficientOfVariation = (arr) => {
+  let nonPositiveNumbers = arr.filter((x) => x <= 0);
+  if (nonPositiveNumbers.length == 0) {
+    let gm = geomMean(arr);
+    let stdev = getStdev(arr);
+    return stdev / gm;
+  } else {
+    return getStdev(arr) / avg(arr);
+  }
+};