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Accepted
Pavlo B.
Asked: 2020-03-21 00:59:25 +0800 CST 2020-03-21 00:59:25 +0800 CST

Sort multidimensional array by the value of an alphanumeric key without changing the indices

  • 772

I have an array like the following:

$lista = [
      '867Ad2' => [
         stock => 2,
         nombre => "cosa1",
      ]
      '838sdff2' => [
         stock => 4,
         nombre => "cosa2",
      ]
      '234hsd4fd' => [
         stock => 6,
         nombre => "cosa3",
      ]  
      '8691240654d' => [
         stock => 8,
         nombre => "cosa4",
      ]
    ]

I order it as I want, by the value of the key 'stock'in this way:

function orderBy($data, $field)
            {
                $code = "return strnatcmp(\$b['$field'], \$a['$field']);";
                sort($data, create_function('$a,$b', $code));
                return $data;
            }

            $sorted_data = orderBy($lista, 'stock');

However, I have noticed that when ordering it, it replaces the indices in the following way:

$lista = [
      '0' => [
         stock => 8,
         nombre => "cosa4",
      ]
      '1' => [
         stock => 6,
         nombre => "cosa3",
      ]
      '2' => [
         stock => 4,
         nombre => "cosa2",
      ]  
      '3' => [
         stock => 2,
         nombre => "cosa1",
      ]
    ]

That is, it replaces my indexes, which are codes with letters and numbers, for a numerical index.

php

1 Answers

  1. Best Answer

    First, by using create_functionimplicitly you are using eval, which is a deprecated practice. Quoting the documentation :

    Caution This function internally performs an eval() and as such has the same security issues as eval(). It also has poor performance characteristics and memory usage.

    Second, what you want to do, to keep the indices while sorting by an arbitrary function, can be done with uasort , and use an anonymous function:

    <?php
$lista = [
      '867Ad2' => [
         'stock' => 2,
         'nombre' => "cosa2",
      ],
      '838sdff2' => [
         'stock' => 1,
         'nombre' => "cosa1",
      ],
      '234hsd4fd' => [
         'stock' => 9,
         'nombre' => "cosa9",
      ],  
      '8691240654d' => [
         'stock' => 8,
         'nombre' => "cosa8",
      ]
    ];

uasort($lista, function ($a, $b) {
            if ($a['stock'] == $b['stock']) {
                return 0;
            }
            return ($a['stock'] < $b['stock']) ? -1 : 1;
        });         


print_r($lista);

    output is

    Array
(
    [838sdff2] => Array
        (
            [stock] => 1
            [nombre] => cosa1
        )

    [867Ad2] => Array
        (
            [stock] => 2
            [nombre] => cosa2
        )

    [8691240654d] => Array
        (
            [stock] => 8
            [nombre] => cosa8
        )

    [234hsd4fd] => Array
        (
            [stock] => 9
            [nombre] => cosa9
        )

)

    uasortpass the array by reference, so your original array is mutated. You don't need to capture the sorted array into a new array.

    I leave you a working fiddle .

    PS: Inside your anonymous function you can perfectly well usestrnatcmp

        uasort($lista, function ($a, $b) {
        return strnatcmp($a['stock'], $b['stock']);
    });

    My answer used a more rudimentary version of comparison just so you understand how this closure works internally. It would be useful for example if you wanted to compare by a second field in case it stockwas the same.

    • 6