How Can I Sort Multi-Dimensional Arrays in PHP by Value?

Sorting Multi-Dimensional Arrays by Value

Sorting data by a specific key value in a multi-dimensional array is a common task. This can be achieved through the use of a user-defined sorting function in conjunction with the usort() or uasort() function.

To sort an array by the "order" key, the following steps can be followed:

1. Define a sorting function (PHP 5.2 or earlier):

function sortByOrder($a, $b) {
    if ($a['order'] > $b['order']) {
        return 1;
    } elseif ($a['order'] < $b['order']) {
        return -1;
    }
    return 0;
}

2. Use usort() with custom sorter:

usort($myArray, 'sortByOrder');

3. Anonymous function (PHP 5.3 ):

usort($myArray, function($a, $b) {
    if ($a['order'] > $b['order']) {
        return 1;
    } elseif ($a['order'] < $b['order']) {
        return -1;
    }
    return 0;
});

4. Spaceship operator (PHP 7):

usort($myArray, function($a, $b) {
    return $a['order'] <=> $b['order'];
});

5. Arrow function (PHP 7.4):

usort($myArray, fn($a, $b) => $a['order'] <=> $b['order']);

Multi-Dimensional Sorting:

To extend sorting to multiple dimensions, the sorting function can be used recursively:

usort($myArray, function($a, $b) {
    $retval = $a['order'] <=> $b['order'];
    if ($retval == 0) {
        $retval = $a['suborder'] <=> $b['suborder'];
        if ($retval == 0) {
            $retval = $a['details']['subsuborder'] <=> $b['details']['subsuborder'];
        }
    }
    return $retval;
});

Preserving Key Associations:

To maintain key associations during sorting, use uasort() instead of usort(). See the PHP manual for a comparison of array sorting functions.

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