按usort排序多维数组

Question

I want to create universal function to sort multidimensional array. For example: I have this array

$arr = [
    [
        'product' => [
            'id' => 32,
        ],
        'price' => 23.8,
    ],
    [
        'product' => [
            'id' => 2,
        ],
        'price' => 150,
    ],
];

And I need to sort by $arr[0]['product']['id'] . I want to use sort smthg like that: usort($arr, sortArray('product.id', 'desc'));

Could you provide some idea how I can do it?

Answer 1

change for DESC as:

return $a['product']['id'] - $b['product']['id'];

change for ASC as:

return $b['product']['id'] - $a['product']['id'];

try this code:

 <?php
$arrrrr = [
    [
        'product' => [
            'id' => 32,
        ],
        'price' => 23.8,
    ],
    [
        'product' => [
            'id' => 2,
        ],
        'price' => 150,
    ],
];


$args = array('product.id','asc');//define an array of args
usort($arrrrr, function($a, $b) use ($args) {
    $firstVal = explode(".",$args[0]);
    if($args[1]=='desc'){
    return $a[$firstVal[0]][$firstVal[1]] - $b[$firstVal[0]][$firstVal[1]];
    }else{
    return $b[$firstVal[0]][$firstVal[1]] - $a[$firstVal[0]][$firstVal[1]];
    }

});


echo '<pre>';print_r($arrrrr);echo '</pre>';
?>

expected output:

Array
(
    [0] => Array
        (
            [product] => Array
                (
                    [id] => 2
                )

            [price] => 150
        )

    [1] => Array
        (
            [product] => Array
                (
                    [id] => 32
                )

            [price] => 23.8
        )

)

Answer 2

The critical part of this is to write an accessor function that takes a single row from your data along with a "path" in dot-notation, eg rating.top .

$accessor = function($row, $path) {
    $steps = explode('.', $path);

    $return = $row[array_shift($steps)];

    while ($level = array_shift($steps)) {
        $return =& $return[$level];
    }

    return $return;
};

This iterates deeper into the array with each step of the path, and resolves to the value at the end. It'll work for an arbitrary number of steps, eg user.rating.top.foo.var.whatever . It's essentially a very cut-down version of Symfony's PropertyAccess component .

Using this, you can construct a callback to pass to usort that will compare the accessed values from the two elements being compared.

usort($array, function ($a, $b) use ($field, $accessor) {
    $aVal = $accessor($a, $field);
    $bVal = $accessor($b, $field);

    return $aVal <=> $bVal;
});

You can see a fully worked version here: https://3v4l.org/UciGc