Leveraging array.prototype.map along with an average function

Question

Leveraging array.prototype.map along with an average function

Despite thoroughly reading the documentation on the map method, I am still unable to make this code work. My objective is to use map to calculate the average of each pair of numbers in an array. Can someone please help me understand what's going wrong?

function getAverage(num1,num2){return Math.ceil((num1+num2)/2)}; 

function calculateAverages(input){ var result = input.map(getAverage(num1,num2)); return result; } 

calculateAverages([1,2,3,4]) // error num1 is not defined
// expected [2,4]

javascript arrays

Answer 1

Answer №1

map applies a function to each element within a list or array, essentially "mapping" the function over all the items.

[1, 2, 3].map(function (number) { return number + 1; });
// -> [2, 3, 4]

Therefore, you must first ensure that your "input" array consists of pairs of items, like so:

var numberPairs = [[1, 2], [3, 4]]

Up until this point, you only have individual numbers and not actual pairs.

Once converted, you can utilize map in the following manner:

numberPairs.map(function (pair) {
  return Math.ceil((pair[0] + pair[1]) / 2);
});

This will yield:

[2, 4]

as the final outcome.

Answer 2

map applies a function to each element within a list or array, essentially "mapping" the function over all the items.

[1, 2, 3].map(function (number) { return number + 1; });
// -> [2, 3, 4]

Therefore, you must first ensure that your "input" array consists of pairs of items, like so:

var numberPairs = [[1, 2], [3, 4]]

Up until this point, you only have individual numbers and not actual pairs.

Once converted, you can utilize map in the following manner:

numberPairs.map(function (pair) {
  return Math.ceil((pair[0] + pair[1]) / 2);
});

This will yield:

[2, 4]

as the final outcome.

Answer 3

Answer №2

Calculating the average using a map is not possible. When you use a map, a function is passed to each element and an array with the same shape is returned. If you want to obtain a value from an array and calculate the average, you should utilize the reduce method.

// Function that adds two numbers
const adder = (a,b) => a + b;
// Reduces the array by adding all numbers and then divides by the length of the array
const getAverage = (arr) => arr.reduce(adder)/arr.length;

// Outputs 2.5 as the result for averaging [1,2,3,4]
console.log(getAverage([1,2,3,4]))

Answer 4

Calculating the average using a map is not possible. When you use a map, a function is passed to each element and an array with the same shape is returned. If you want to obtain a value from an array and calculate the average, you should utilize the reduce method.

// Function that adds two numbers
const adder = (a,b) => a + b;
// Reduces the array by adding all numbers and then divides by the length of the array
const getAverage = (arr) => arr.reduce(adder)/arr.length;

// Outputs 2.5 as the result for averaging [1,2,3,4]
console.log(getAverage([1,2,3,4]))

Answer 5

Answer №3

If you want to calculate the average of every n values in an array, try using the reduce() method instead of map():

const total = arr => arr.reduce((acc, value) => acc + value, 0);
const computeAverage = n => (averages, val, index, arr) => index % n === 0
  ? [...averages, Math.ceil(total(arr.slice(index, index + n)) / n)]
  : averages

const result = [1, 2, 3, 4].reduce(computeAverage(2), [])
console.log(result)

Answer 6

If you want to calculate the average of every n values in an array, try using the reduce() method instead of map():

const total = arr => arr.reduce((acc, value) => acc + value, 0);
const computeAverage = n => (averages, val, index, arr) => index % n === 0
  ? [...averages, Math.ceil(total(arr.slice(index, index + n)) / n)]
  : averages

const result = [1, 2, 3, 4].reduce(computeAverage(2), [])
console.log(result)

Leveraging array.prototype.map along with an average function

Answer №1

Answer №2

Answer №3

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