what's the best way to order an array using another in PHP?

Question

Suppose I have an array that I want to sort, and the order is not something computable, but rather, given by another array which lists the keys in the desired order:

$ordering_array = [
    'c',
    'a',
    'k',
    'e',
];

As an added complication, not all of these keys might be present in my array to sort:

$given_array = [
    'a' => 'value',
    'c' => 'value',
    'e' => 'value',
];

What is the cleanest / quickest way to achieve this?

My method is:

$new_array = array_fill_keys($ordering_array, NULL);

foreach ($given_array as $key => $value) {
  $new_array[$key] = $value;
}

$new_array = array_filter($new_array);

Is there a better way?

https://stackoverflow.com/questions/11145393/sorting-a-php-array-of-arrays-by-custom-order — Jayakrishnan, Jun 22 '18 at 07:05
Just so you know, `array_filter()` is going to kill all `falsey` values with extreme prejudice. — mickmackusa, Jul 02 '18 at 00:12
Possible duplicate of [Sort an Array by keys based on another Array?](https://stackoverflow.com/questions/348410/sort-an-array-by-keys-based-on-another-array) — mickmackusa, Jul 02 '18 at 00:15

score 2 · Accepted Answer · answered Jun 22 '18 at 06:52

2

You can replace the foreach with array_replace()

$new_array = array_fill_keys($ordering_array, NULL);
$new_array = array_replace($new_array, $given_array);
$new_array = array_filter($new_array);

answered Jun 22 '18 at 06:52

Nigel Ren

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rkj · Answer 2 · 2018-06-22T07:13:57.083

1

you can try this

$filteredKeys = array_intersect_key(array_flip($ordering_array), $given_array);
$outputArray = array_merge($filteredKeys, $given_array);

edited Jun 22 '18 at 07:13

answered Jun 22 '18 at 06:53

rkj

8,067
2
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@C2486 fixed it, please check it now – rkj Jun 22 '18 at 07:14

Jagjeet Singh · Answer 3 · 2018-06-22T07:12:18.453

1

Use array_merge() or array_replace at the place of foreach, both worked

Try this:

$ordering_array = ['c', 'a', 'k', 'e'];
$given_array = ['a' => 'value', 'c' => 'value', 'e' => 'value'];

$new_array = array_fill_keys($ordering_array, NULL);

$new_array = array_merge($new_array, $given_array);
                       OR
$new_array = array_replace($new_array, $given_array);

$new_array = array_filter($new_array);

edited Jun 22 '18 at 07:12

answered Jun 22 '18 at 06:56

Jagjeet Singh

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What you have changed from [this answer](https://stackoverflow.com/a/50982247/2815635) ? – Niklesh Raut Jun 22 '18 at 07:00

score 1 · Answer 4 · answered Jun 22 '18 at 07:07

This is a oneliner that solves it:

$ordering_array = ['c', 'a', 'k', 'e'];
$given_array = ['a' => 'value', 'c' => 'value', 'e' => 'value'];
$outputArray = array_merge(array_intersect_key(array_flip($ordering_array), $given_array), $given_array);
print_r($outputArray);

@rkj was close, but this is how it's done

Test here: http://sandbox.onlinephpfunctions.com/code/95b30f6e402b1afdb18867471888ff8ba38867de

score 0 · Answer 5 · answered Jun 22 '18 at 07:34

0

try using uksort,

demo

<?php 
    $ordering_array  = [
        'c',
        'a',
        'k',
        'e',
    ];
    $given_array  = [
        'a' => 'value-a',
        'c' => 'value-c',
        'e' => 'value-e',
    ];

    uksort($given_array , function ($a, $b) use ($ordering_array) {

        $pos_a = array_search($a,$ordering_array);
        $pos_b = array_search($b,$ordering_array);
        return $pos_a - $pos_b;
    });

    var_dump($given_array );

answered Jun 22 '18 at 07:34

Jayakrishnan

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If you flip the ordering_array you can throw away the array_search lines, and change the return to: `return $ordering_array[$a] - $ordering_array[$b];` – Progrock Jun 22 '18 at 08:01

score 0 · Answer 6 · answered Jun 22 '18 at 07:52

Simple and explicit:

<?php    
$ordering_array = [
    'c',
    'a',
    'k',
    'e',
];

$given_array = [
    'a' => 'valuea',
    'c' => 'valuec',
    'e' => 'valuee',
];

foreach($ordering_array as $K)
    if(array_key_exists($K, $given_array))
        $ordered[$K] = $given_array[$K];

var_export($ordered);

Output:

array (
  'c' => 'valuec',
  'a' => 'valuea',
  'e' => 'valuee',
)

You might be able to shave off a byte or two with isset($given_array[$K]) if the data allows.

what's the best way to order an array using another in PHP?

6 Answers6