CODEWITHSUNDEEP
phparraysdatabasesorting
A. Volg
A. Volg

Reputation: 307

Sort nested array using another array with PHP

I got this array, comes from database. The order of values is changeable by the users

Array
 (
   [0] => 14
   [1] => 15
   [2] => 9
   [3] => 13
   [4] => 12
   ...
   [n] => n
 )

There is another array, which will be extracted to browser:

  Array
  (
   [0] => Array
    (
        [id] => 1
        ...
        [nr] => 9
        ...
    )
   [1] => Array
   (
        [id] => 2
        ...
        [nr] => 12
        ...
    )
    [2] => Array
   (
        [id] => 3
        ...
        [nr] => 15
        ...
    )
    [n] => Array
  )

I need to find a way to sort the this second array by nr (not id) and the nr order comes from the first array.

Any ideas?

Upvotes: 1

Views: 97

Answers (2)

Progrock
Progrock

Reputation: 7485

You can just map your values to keys, and use that map to re-order.

<?php

$order = 
[
    2,
    5,
    1
];

$items =
[
    ['o' => 1],
    ['o' => 5],
    ['o' => 2],
];

foreach($items as $k => $v) {
    $map[$v['o']] = $k;
}

var_export($map);

foreach($order as $o) {
    $k = $map[$o];
    $result[$k] = $items[$k];
}

var_export($result);

Output:

array (
    1 => 0,
    5 => 1,
    2 => 2,
  )array (
    2 => 
    array (
      'o' => 2,
    ),
    1 => 
    array (
      'o' => 5,
    ),
    0 => 
    array (
      'o' => 1,
    ),
  )

Assuming there's a one-one mapping.

Upvotes: 1

Mihai Matei
Mihai Matei

Reputation: 24276

You can flip the first array in order to know what's the order of the id's:

$order = array_flip($order);

Then you simply use usort to sort the array based on the earlier flipped array:

usort($array, static function(array $a, array $b) use ($order) {
    return $order[$a['nr']] <=> $order[$b['nr']];
});

Upvotes: 2

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