How do I sort a multi-dimensional array by value?

问题

I have an array as following and I want to order that array by the value of the key "attack". First keys of the arrays (15, 13, 18) are ID of some certain item from database, so I don't want these keys to be changed when the array is sorted. Any help would be greatly appreciated.

This is the array:

$data = array(
    '15' => array(
        'attack' => '45', 'defence' => '15', 'total' => '10'
    ),
    '13' => array(
        'attack' => '25', 'defence' => '15', 'total' => '10'
    ),
    '18' => array(
        'attack' => '35', 'defence' => '15', 'total' => '10'
    )
);

回答1:

Use uasort():

This function sorts an array such that array indices maintain their correlation with the array elements they are associated with, using a user-defined comparison function.

This is used mainly when sorting associative arrays where the actual element order is significant.

Example:

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

uasort($data, 'cmp');

If the values are always strings, you can also use strcmp() in the cmp() function:

function cmp($a, $b) {
    return strcmp($a['attack'], $b['attack']);
}

Update:

To sort in descending order you just have to change the return values:

return ($a['attack'] < $b['attack']) ? 1 : -1;
//                                     ^----^

or to pick up @salathe's proposal:

return $b['attack'] - $a['attack'];

回答2:

Simply use array_multisort

foreach ($data as $key => $row) {
    $attack[$key]  = $row['attack'];
}

// Sort the data with attack descending
array_multisort($attack, SORT_DESC, $data);

Hope this helps.

回答3:

$result = [];
foreach ($data as $key => $value) {
    $result[$key] = $value;
    asort($result[$key]);
}
print_r($result);

Hope this helps !!!

来源：https://stackoverflow.com/questions/3281841/how-do-i-sort-a-multi-dimensional-array-by-value

标签

php

arrays

sorting

multidimensional-array