Lodash _.meanBy() Method

Lodash is a JavaScript library that works on the top of underscore.js. Lodash helps in working with arrays, strings, objects, numbers, etc.

The _.meanBy() method is used to compute the mean value from the original array by iterating over each element in the array using the Iteratee function. It is almost the same as _.mean() function.

Syntax:

_.meanBy( array, [iteratee = _.identity] )

Parameters: This method accepts two parameters as mentioned above and described below:

• array: It is the array that the method iterates over to get the mean of all the elements.
• iteratee: It is the function that is invoked for every element in the array.

Return Value: This method returns the mean value of the array.

Example 1:

Javascript

// Requiring the lodash library
const _ = require("lodash");

// Original array
var arr = [{ 'n': 4 }, { 'n': 2 }, { 'n': 6 }];

// Use of _.meanBy() method
let mean_val =
  _.meanBy(arr, function(o) { return o.n; });

// Printing the output
console.log(mean_val);

Output:

4

Example 2:  

Javascript

// Requiring the lodash library
const _ = require("lodash");

// Original array
var arr = [{ 'n': 10 }, { 'n': 5 },
           { 'n': 3 }, { 'n': 12 }];

// Use of _.meanBy()
// method
let mean_val = _.meanBy(arr, 'n');

// Printing the output
console.log(mean_val);

Output:

7.5