Adding arrays in javascript

Question

Adding arrays in javascript

Consider the following arrays:

// The goal is to calculate these arrays against each other.
var a = [1,2,3]
var b = [1,2,3]
var c = [3,4,5]
// ->
var result = [5, 8, 11]

While there are methods available to calculate two arrays at a time, how can we sum n arrays together?

Array.prototype.Sum = function (arr) {
    var s = [];
    if (arr != null && this.length == arr.length) {
        for (var i = 0; i < arr.length; i++) {
            var c = this[i] + arr[i]
            s.push(c);
        }
    }
    return s;
}

javascript arrays

Answer 1

Answer №1

Suppose

let arrays = [
    [1,2,3],
    [1,2,3],
    [3,4,5]
];

Utilizing the Sum function with EcmaScript 5 array methods,

let result = arrays.reduce(function(arr1, arr2){
    return arr1.Sum(arr2);
});

Alternatively, you can avoid extending Array.prototype and opt for something like this (ES5)

let result = arrays.reduce(function(arr1, arr2) {
    return arr1.map(function(num, index){
        return num+arr2[index];
    });
});

Or, simplify using EcmaScript 6 arrow functions,

let result = arrays.reduce(
    (arr1, arr2) => arr1.map(
        (num, index) => num+arr2[index]
    )
);

Answer 2

Suppose

let arrays = [
    [1,2,3],
    [1,2,3],
    [3,4,5]
];

Utilizing the Sum function with EcmaScript 5 array methods,

let result = arrays.reduce(function(arr1, arr2){
    return arr1.Sum(arr2);
});

Alternatively, you can avoid extending Array.prototype and opt for something like this (ES5)

let result = arrays.reduce(function(arr1, arr2) {
    return arr1.map(function(num, index){
        return num+arr2[index];
    });
});

Or, simplify using EcmaScript 6 arrow functions,

let result = arrays.reduce(
    (arr1, arr2) => arr1.map(
        (num, index) => num+arr2[index]
    )
);

Answer 3

Answer №2

Here is a simple ECMAScript 3 solution:

var arrays = [
    [1, 2, 3],
    [1, 2, 3],
    [3, 4, 5]
];

function sum() {
  var total = [];
  for(var i = 0; i < arguments.length; ++i) {
    for(var j = 0; j < arguments[i].length; ++j)
      total[j] = (total[j] || 0) + arguments[i][j];
  } return total;
}

sum.apply(this, arrays);              // [ 5, 8, 11 ]
sum(arrays[0], arrays[1], arrays[2]); // [ 5, 8, 11 ]

Answer 4

Here is a simple ECMAScript 3 solution:

var arrays = [
    [1, 2, 3],
    [1, 2, 3],
    [3, 4, 5]
];

function sum() {
  var total = [];
  for(var i = 0; i < arguments.length; ++i) {
    for(var j = 0; j < arguments[i].length; ++j)
      total[j] = (total[j] || 0) + arguments[i][j];
  } return total;
}

sum.apply(this, arrays);              // [ 5, 8, 11 ]
sum(arrays[0], arrays[1], arrays[2]); // [ 5, 8, 11 ]

Answer 5

Answer №3

This unique function allows you to add multiple arrays without the need to nest them within another array...

Furthermore, it is compatible with older browsers.

function CombineArrays(){
  if (arguments.length == 0){
    return null;
  }
  var sum = arguments[0];
  for(var j = 1; j < arguments.length; j++) {
     var arr = arguments[j];
     for (var i = 0; i < arr.length; i++) {
         sum[i] = sum[i] + arr[i];
     }
  }
  return sum;
}

Simply use CombineArrays(a, b) or CombineArrays(a, b, c) ...

If desired, this function can also be placed in your prototype (with modifications to utilize this for in-place summation).

Answer 6

This unique function allows you to add multiple arrays without the need to nest them within another array...

Furthermore, it is compatible with older browsers.

function CombineArrays(){
  if (arguments.length == 0){
    return null;
  }
  var sum = arguments[0];
  for(var j = 1; j < arguments.length; j++) {
     var arr = arguments[j];
     for (var i = 0; i < arr.length; i++) {
         sum[i] = sum[i] + arr[i];
     }
  }
  return sum;
}

Simply use CombineArrays(a, b) or CombineArrays(a, b, c) ...

If desired, this function can also be placed in your prototype (with modifications to utilize this for in-place summation).

Answer 7

Answer №4

Function a adds b and then adds c;

Executing this should yield the desired result.

Answer 8

Function a adds b and then adds c;

Executing this should yield the desired result.

Adding arrays in javascript

Answer №1

Answer №2

Answer №3

Answer №4

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