Sort array by highest possible subarray value

Question

I have a question similar to this one: PHP Sort Array By SubArray Value however it is a bit different since I want to find/search for the highest of many subarray values and sort the "main" array after that. Below is the array structure I have, with groupings that contain a number of subitems where each subitem has a score.

Array
(
    [grouping1] => Array
        (
            [0] => Array
                (
                    [_score] => 8.2
                    [_source] => Array
                        (
                            [name] => Subitem 1111,
                            [ID => 999
                        )

                )

        )

    [grouping2] => Array
        (
            [0] => Array
                (
                    [_score] => 8.546042
                    [_source] => Array
                        (
                            [name] => Subitem2222,
                            [ID] => 987654
                        )

                )

        )

    [grouping3] => Array
        (
            [0] => Array
                (
                    [_score] => 10.163501
                    [_source] => Array
                        (
                            [name] => Subitem3333
                            [ID] => 12345

                        )

                )

            [1] => Array
                (
                    [_score] => 8.55
                    [_source] => Array
                        (
                            [name] => Subitem4444,
                            [ID] => 67890
                        )

                )

            [2] => Array
                (
                    [_score] => 9.55
                    [_source] => Array
                        (
                            [name] => Subitem5555
                            [ID] => 65421
                        )

                )

        )

)

I would like to

Check the highest score amongst subitems for each grouping
Sort groupings after highest available subitem score

The expected output is the containing array to have this order

[0] grouping3 since its highest subarray score is 10.163501
[1] grouping2 since its highest subarray score is 8.546042
[2] grouping1 since its highest subarray score is 8.2

Couldn't you delete the _index and _source values? It seems to me they are not necessary for this problem — yunzen, Oct 18 '18 at 12:17
Possible duplicate of [PHP Sort Array By SubArray Value](https://stackoverflow.com/questions/2477496/php-sort-array-by-subarray-value) — William Perron, Oct 18 '18 at 12:20
Thanks, I removed the _index values and explained the expected output. — Oscar, Oct 18 '18 at 12:25
What if `grouping` has items with different `score`, how are they sorted? — u_mulder, Oct 18 '18 at 12:26
@u_mulder sorry that was unclear - subitems can have different scores like 8.55, 9.55 and 10.1 (edited now). They will be sorted randomly inside the grouping. But the highest subitem score should represent the grouping — Oscar, Oct 18 '18 at 12:30

u_mulder · Accepted Answer · 2018-10-18T13:19:05.403

0

Okay, that's what you need to do - find max score in each grouping and store a lookup [grouping -> score], then sort this lookup array preserving keys and build new array:

$lookup = [];
foreach ($source_array as $key => $grouping) {
    $max = 0;
    foreach ($grouping as $item) {
        if ($max < $item['_score']) {
            $max = $item['_score'];
        }
    }
    $lookup[$key] = $max;
}

// sort `$lookup` preserving keys
arsort($lookup);

$sorted_array = [];
foreach ($lookup as $key => $max) {
    $sorted_array[$key] = $source_array[$key];
}

edited Oct 18 '18 at 13:19

answered Oct 18 '18 at 12:38

u_mulder

54,101
5
48
64

I changed $sorted_array[$key] = $array[$key]; to $sorted_array[$key] = $source_array[$key]; and it seems to be working. Think it's a correct change? – Oscar Oct 18 '18 at 13:11

Sort array by highest possible subarray value

1 Answers1