sort an array with another array which has sorted keys

Question

How to sort an 1st array with 2nd array which has sorted keys in 2nd array without using any loop.

1st Array.

$chunk = array(
                [0] => Array
                    (
                        [id] => 212
                        [order] => 1
                        [title] => fdfdfdfdf
                    )

                [1] => Array
                    (
                        [id] => 5
                        [order] => 2
                        [title] => 
                    )

                [2] => Array
                    (
                        [id] => 781
                        [order] => 3
                        [title] => 
                    )
            )

2nd array with sorted keys of 1st array.

$sort = array
    (
        [2] => 2
        [0] => 0
        [1] => 1
    )

Possible [XY Problem](https://meta.stackexchange.com/questions/66377/what-is-the-xy-problem). How are you getting the 2nd array? Maybe at that moment you can already sort 1st array. — FirstOne, Jun 07 '17 at 13:29
You could go with [usort](http://php.net/manual/en/function.usort.php), like so: [https://3v4l.org/MIJN6](https://3v4l.org/MIJN6). If that's the case, so maybe a dup?: [**PHP Sort Array By SubArray Value**](https://stackoverflow.com/questions/2477496/php-sort-array-by-subarray-value) — FirstOne, Jun 07 '17 at 13:42

score 1 · Accepted Answer · answered Jun 07 '17 at 13:22

You could use array_map for that:

$arr = array_map(function($val) use($chunk){
    return $chunk[$val];
}, $sort);

This is the output:

Array
(
    [2] => Array
        (
            [id] => 781
            [order] => 3
            [title] => 
        )

    [0] => Array
        (
            [id] => 212
            [order] => 1
            [title] => fdfdfdfdf
        )

    [1] => Array
        (
            [id] => 5
            [order] => 2
            [title] => 
        )

)

Now, if you want the keys to be 0,1,2..., you can use array_values, after mapping:

$arr = array_values($arr);

And the output:

Array
(
    [0] => Array
        (
            [id] => 781
            [order] => 3
            [title] => 
        )

    [1] => Array
        (
            [id] => 212
            [order] => 1
            [title] => fdfdfdfdf
        )

    [2] => Array
        (
            [id] => 5
            [order] => 2
            [title] => 
        )

)

can u please explain what anonymous function with use keyword doing. — AMit SiNgh, Jun 08 '17 at 05:16
@amitsingh array_map calls a callback for each element in a given array. That's in the docs. Now, the `use` part is there because, since we are inside a function, it's a different scope, so technically we don't have access to outside variables. When we add `use`, that given variable becomes accessible. [Callback function using variables calculated outside of it](https://stackoverflow.com/questions/4588714/php-callback-function-using-variables-calculated-outside-of-it) — FirstOne, Jun 08 '17 at 10:11

score 0 · Answer 2 · answered Jun 07 '17 at 13:17

Of course, there is no function for this. You'll have to do something similar

<?php
$chunk  = [
    // data
];
$sorted = [];
$sort   = [
    // ordered keys
];

foreach($sort as $keyToFind) {
    foreach($chunk as $arrayElement) {
        if($arrayElement['id'] == $keyToFind)) {
            $sorted[$keyToFind] = $arrayElement;
        }
    }
}

As you can see, this is a bit time and ressources consumming because of the two imbricated foreaches. Let's hope your arrays are not so big

sort an array with another array which has sorted keys

2 Answers2