getArithmeticMeanFromFrequency()

src/main/statistics.ts

@@ -13,6 +13,20 @@ export const getArithmeticMean = (data: number[], decimalPlaces = Infinity) : nu
     return setDecimalPlaces(sum / data.length, decimalPlaces);
 };
 
+/**
+ * Frequency map: number ---> it's frequency
+ */
+export const getArithmeticMeanFromFrequency = (frequencyMap: Map<number, number>, decimalPlaces = Infinity) => {
+
+    let mean = 0;
+
+    for(const [val, frequency] of frequencyMap) {
+        mean += val * frequency;
+    }
+
+    return setDecimalPlaces(mean, decimalPlaces);
+};
+
 /**
  * Central tendency: What is the central number in the sorted array?
  * Good for lists like [3, 3, 3, 3, 3, 3, 100] - 100 here is called "Outlier"

test/statistics.test.ts

@@ -4,7 +4,8 @@ import {
     getMode,
     getVariance,
     getVariance1,
-    getStandardDeviation
+    getStandardDeviation,
+    getArithmeticMeanFromFrequency,
 } from '../src/main/statistics';
 
 describe('Statistics', () => {
@@ -34,6 +35,18 @@ describe('Statistics', () => {
             });
         });
 
+        describe('getArithmeticMeanFromFrequency()', () => {
+
+            test('map 1', () => {
+                const map = new Map();
+                map.set(3, 0.6); // 60% of number 3
+                map.set(4, 0.2); // 20% of number 4
+                map.set(5, 0.2); // 20% of number 5
+
+                expect(getArithmeticMeanFromFrequency(map, 2)).toStrictEqual(3.6);
+            });
+        });
+
         describe('getMedian()', () => {
 
             test('[]', () => {