Create array from another with specific indices

Question

I have two arrays, one of data and one of indices:

var data = [
    'h', 'e', 'l', 'l', 'o', ' '
];
var indices = [
    4, 0, 5, 0, 1, 2, 2
];

I would like to create a third array, using cells of data in order indicated in indices, so it here it would be:

['o', 'h', ' ', 'h', 'e', 'l', 'l']

I know I could easily do it with a simple loop:

var newArray = new Array(indices.length);
for (var i in indices) {
    var index = indices[i];
    newArray.push(data[index]);
}

But I wonder if there is a cleaner/simpler way to do it, like an array method or a special constructor ?

Oleksandr T. · Accepted Answer · 2015-06-22 08:49:55Z

5

You can use .map, like so

var data = [
    'h', 'e', 'l', 'l', 'o', ' '
];

var indices = [
    4, 0, 5, 0, 1, 2, 2
];

var res = indices.map(function (el) {
  return data[el];
});

console.log(res);

The map() method creates a new array with the results of calling a provided function on every element in this array.

answered Jun 22, 2015 at 8:49

Oleksandr T.

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TaoPR · Accepted Answer · 2015-06-22 08:51:10Z

2

You can also use map

var newArray = indices.map(function(i){
    return data[i]
});

answered Jun 22, 2015 at 8:51

TaoPR

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Comments

user2575725 · Accepted Answer · 2015-06-22 08:54:52Z

0

You could have used while loop:

var data = [
  'h', 'e', 'l', 'l', 'o', ' '
];
var indices = [
  4, 0, 5, 0, 1, 2, 2
];
var l = indices.length,
  newArray = [];
while (l--)
  newArray[l] = data[indices[l]];
console.log(newArray);

answered Jun 22, 2015 at 8:54

user2575725

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