merge: Improve Mean method (TheAlgorithms#874)

Author: Yatin-kathuria

Maths/AverageMean.js

@@ -1,29 +1,23 @@
-'use strict'
-/*
- author: PatOnTheBack
- license: GPL-3.0 or later
-
- Modified from:
- https://github.com/TheAlgorithms/Python/blob/master/maths/average.py
-
- This script will find the average (mean) of an array of numbers.
-
- More about mean:
- https://en.wikipedia.org/wiki/Mean
-*/
+/**
+ * @function mean
+ * @description This script will find the mean value of a array of numbers.
+ * @param {Integer[]} nums - Array of integer
+ * @return {Integer} - mean of nums.
+ * @see [Mean](hhttps://en.wikipedia.org/wiki/Mean)
+ * @example mean([1, 2, 4, 5]) = 3
+ * @example mean([10, 40, 100, 20]) = 42.5
+ */
 
 const mean = (nums) => {
- // This is a function returns average/mean of array
- let sum = 0
+ if (!Array.isArray(nums)) {
+ throw new TypeError('Invalid Input')
+ }
 
  // This loop sums all values in the 'nums' array using forEach loop
- nums.forEach(function (current) {
- sum += current
- })
+ const sum = nums.reduce((sum, cur) => sum + cur, 0)
 
  // Divide sum by the length of the 'nums' array.
- const avg = sum / nums.length
- return avg
+ return sum / nums.length
 }
 
 export { mean }

Maths/test/AverageMean.test.js

@@ -4,8 +4,18 @@ describe('Tests for average mean', () => {
  it('should be a function', () => {
  expect(typeof mean).toEqual('function')
  })
+
+ it('should throw error for invalid input', () => {
+ expect(() => mean(123)).toThrow()
+ })
+
  it('should return the mean of an array of numbers', () => {
  const meanFunction = mean([1, 2, 4, 5])
  expect(meanFunction).toBe(3)
  })
+
+ it('should return the mean of an array of numbers', () => {
+ const meanFunction = mean([10, 40, 100, 20])
+ expect(meanFunction).toBe(42.5)
+ })
 })