[php] How to Sort Multi-dimensional Array by Value?

How can I sort this array by the value of the "order" key? Even though the values are currently sequential, they will not always be.

Array
(
    [0] => Array
        (
            [hashtag] => a7e87329b5eab8578f4f1098a152d6f4
            [title] => Flower
            [order] => 3
        )

    [1] => Array
        (
            [hashtag] => b24ce0cd392a5b0b8dedc66c25213594
            [title] => Free
            [order] => 2
        )

    [2] => Array
        (
            [hashtag] => e7d31fc0602fb2ede144d18cdffd816b
            [title] => Ready
            [order] => 1
        )
)

I use this function :

function array_sort_by_column(&$arr, $col, $dir = SORT_ASC) {
    $sort_col = array();
    foreach ($arr as $key=> $row) {
        $sort_col[$key] = $row[$col];
    }

    array_multisort($sort_col, $dir, $arr);
}


array_sort_by_column($array, 'order');

Use array_multisort(), array_map()

array_multisort(array_map(function($element) {
      return $element['order'];
  }, $array), SORT_ASC, $array);

print_r($array);

DEMO

One approach to achieve this would be like this

    $new = [
              [
                'hashtag' => 'a7e87329b5eab8578f4f1098a152d6f4',
                'title' => 'Flower',
                'order' => 3,
              ],

              [
                'hashtag' => 'b24ce0cd392a5b0b8dedc66c25213594',
                'title' => 'Free',
                'order' => 2,
              ],

              [
                'hashtag' => 'e7d31fc0602fb2ede144d18cdffd816b',
                'title' => 'Ready',
                'order' => 1,
              ],
    ];

    $keys = array_column($new, 'order');

    array_multisort($keys, SORT_ASC, $new);

    var_dump($new);

Result:

    Array
    (
        [0] => Array
            (
                [hashtag] => e7d31fc0602fb2ede144d18cdffd816b
                [title] => Ready
                [order] => 1
            )

        [1] => Array
            (
                [hashtag] => b24ce0cd392a5b0b8dedc66c25213594
                [title] => Free
                [order] => 2
            )

        [2] => Array
            (
                [hashtag] => a7e87329b5eab8578f4f1098a152d6f4
                [title] => Flower
                [order] => 3
            )

    )

I usually use usort, and pass my own comparison function. In this case, it is very simple:

function compareOrder($a, $b)
{
  return $a['order'] - $b['order'];
}
usort($array, 'compareOrder');

In PHP 7 using spaceship operator:

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

To sort the array by the value of the "title" key use:

uasort($myArray, function($a, $b) {
    return strcmp($a['title'], $b['title']);
});

strcmp compare the strings.

uasort() maintains the array keys as they were defined.

This solution is for usort() with an easy-to-remember notation for multidimensional sorting. The spaceship operator <=> is used, which is available from PHP 7.

usort($in,function($a,$b){
  return $a['first']   <=> $b['first']  //first asc
      ?: $a['second']  <=> $b['second'] //second asc
      ?: $b['third']   <=> $a['third']  //third desc (a b swapped!)
      //etc
  ;
});

Examples:

$in = [
  ['firstname' => 'Anton', 'surname' => 'Gruber', 'birthdate' => '03.08.1967', 'rank' => 3],
  ['firstname' => 'Anna', 'surname' => 'Egger', 'birthdate' => '04.01.1960', 'rank' => 1],
  ['firstname' => 'Paul', 'surname' => 'Mueller', 'birthdate' => '15.10.1971', 'rank' => 2],
  ['firstname' => 'Marie', 'surname' => 'Schmidt ', 'birthdate' => '24.12.1963', 'rank' => 2],
  ['firstname' => 'Emma', 'surname' => 'Mueller', 'birthdate' => '23.11.1969', 'rank' => 2],
];

first task: Order By rank asc, surname asc

usort($in,function($a,$b){
  return $a['rank']      <=> $b['rank']     //first asc
      ?: $a['surname']   <=> $b['surname']  //second asc
  ;
});

second task: Order By rank desc, surname asc, firstmame asc

usort($in,function($a,$b){
  return $b['rank']      <=> $a['rank']       //first desc
      ?: $a['surname']   <=> $b['surname']    //second asc
      ?: $a['firstname'] <=> $b['firstname']  //third asc
  ;
});

third task: Order By rank desc, birthdate asc

The date cannot be sorted in this notation. It is converted with strtotime.

usort($in,function($a,$b){
  return $b['rank']      <=> $a['rank']       //first desc
      ?: strtotime($a['birthdate']) <=> strtotime($b['birthdate'])    //second asc
  ;
});

The most flexible approach would be using this method

Arr::sortByKeys(array $array, $keys, bool $assoc = true): array

here's why:

• You can sort by any key (also nested like 'key1.key2.key3' or ['k1', 'k2', 'k3'])

• Works both on associative and not associative arrays ($assoc flag)

• It doesn't use reference - return new sorted array

In your case it would be as simple as:

$sortedArray = Arr::sortByKeys($array, 'order');

This method is a part of this library.

If anyone need sort according to key best is to use below

usort($array, build_sorter('order'));

function build_sorter($key) {
   return function ($a, $b) use ($key) {
      return strnatcmp($a[$key], $b[$key]);
   };
}

$sort = array();
$array_lowercase = array_map('strtolower', $array_to_be_sorted);
array_multisort($array_lowercase, SORT_ASC, SORT_STRING, $alphabetically_ordered_array);

This takes care of both upper and lower case alphabets.

Let's face it: php does NOT have a simple out of the box function to properly handle every array sort scenario.

This routine is intuitive, which means faster debugging and maintenance:

// automatic population of array
$tempArray = array();
$annotations = array();
// ... some code
// SQL $sql retrieves result array $result 
// $row[0] is the ID, but is populated out of order (comes from 
// multiple selects populating various dimensions for the same DATE 
// for example
while($row = mysql_fetch_array($result)) {
    $needle = $row[0];
    arrayIndexes($needle);  // create a parallel array with IDs only
    $annotations[$needle]['someDimension'] = $row[1]; // whatever
}
asort($tempArray);
foreach ($tempArray as $arrayKey) {
    $dataInOrder = $annotations[$arrayKey]['someDimension']; 
    // .... more code
}

function arrayIndexes ($needle) {
    global $tempArray;
    if (!in_array($needle,$tempArray)) {
        array_push($tempArray,$needle);
    }
}

function aasort (&$array, $key) {
    $sorter=array();
    $ret=array();
    reset($array);
    foreach ($array as $ii => $va) {
        $sorter[$ii]=$va[$key];
    }
    asort($sorter);
    foreach ($sorter as $ii => $va) {
        $ret[$ii]=$array[$ii];
    }
    $array=$ret;
}

aasort($your_array,"order");