Question

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Changing a nested (multidimentional) array into key => value pairs in PHP

I have this array

[5] => Array
        (
            [completed_system_products_id] => 1
            [completed_systems_id] => 76
            [step_number] => 1
            [product_id] => 92
            [category] => hardware
            [date_added] => 2011-05-03 13:44:01
        )

    [4] => Array
        (
            [completed_system_products_id] => 2
            [completed_systems_id] => 76
            [step_number] => 2
            [product_id] => 62
            [category] => hardware
            [date_added] => 2011-05-03 13:44:51
        )

    [3] => Array
        (
            [completed_system_products_id] => 3
            [completed_systems_id] => 76
            [step_number] => 3
            [product_id] => 104
            [category] => hardware
            [date_added] => 2011-05-03 13:44:56
        )

    [2] => Array
        (
            [completed_system_products_id] => 4
            [completed_systems_id] => 76
            [step_number] => 4
            [product_id] => 251
            [category] => hardware
            [date_added] => 2011-05-03 13:48:56
        )

How do i make the keys values the same as the [step_number] =>

so for example i want this outcome

    [1] => Array
        (
            [completed_system_products_id] => 1
            [completed_systems_id] => 76
            [step_number] => 1
            [product_id] => 92
            [category] => hardware
            [date_added] => 2011-05-03 13:44:01
        )

    [2] => Array
        (
            [completed_system_products_id] => 2
            [completed_systems_id] => 76
            [step_number] => 2
            [product_id] => 62
            [category] => hardware
            [date_added] => 2011-05-03 13:44:51
        )

    [3] => Array
        (
            [completed_system_products_id] => 3
            [completed_systems_id] => 76
            [step_number] => 3
            [product_id] => 104
            [category] => hardware
            [date_added] => 2011-05-03 13:44:56
        )

    [4] => Array
        (
            [completed_system_products_id] => 4
            [completed_systems_id] => 76
            [step_number] => 4
            [product_id] => 251
            [category] => hardware
            [date_added] => 2011-05-03 13:48:56
        )

Answer 1

$new = array();
foreach ($old as $value) {
    $new[$value['step_number']] = $value;
}
$old = $new;