php - php多次元配列ソートの問題

Question

複雑な多次元配列があります。構造はこんな感じ

Array
(
    [0] => Array
        (
            [countries] => Array
                (
                    [0] => Array
                        (
                            [country_code] => US                            
                            [growth] => 3.57
                        )

                    [1] => Array
                        (
                            [country_code] => CA                            
                            [growth] => 4.77
                        )

                    [2] => Array
                        (
                            [country_code] => TT                            
                            [growth] => 0
                        )
                )
            [group_name] => North America
        )

    [1] => Array
        (
            [countries] => Array
                (
                    [0] => Array
                        (
                            [country_code] => BR                           
                            [growth] => 2.19
                        )

                    [1] => Array
                        (
                            [country_code] => PE                           
                            [growth] => 1.78
                        )

                    [2] => Array
                        (
                            [country_code] => UY                           
                            [growth] => 8.83
                        )

                    [3] => Array
                        (
                            [country_code] => MX                           
                            [growth] => 3.83
                        )
                )
            [group_name] => South America
        )
)

array_multisort（を使用して）並べ替えて、growth（最も高いものから）順に並べ替えたい

ソートされた配列が

Array
(
    [0] => Array
        (
            [countries] => Array
                (
                    [0] => Array
                        (
                            [country_code] => CA                            
                            [growth] => 4.77
                        )
                    [1] => Array
                        (
                            [country_code] => US                            
                            [growth] => 3.57
                        )                 
                    [2] => Array
                        (
                            [country_code] => TT                            
                            [growth] => 0
                        )
                )
            [group_name] => North America
        )

    [1] => Array
        (
            [countries] => Array
                (
                   [0] => Array
                        (
                            [country_code] => UY                           
                            [growth] => 8.83
                        )

                   [1] => Array
                        (
                            [country_code] => MX                           
                            [growth] => 3.83
                        )
                    [2] => Array
                        (
                            [country_code] => BR                           
                            [growth] => 2.19
                        )

                    [3] => Array
                        (
                            [country_code] => PE                           
                            [growth] => 1.78
                        )
                )
            [group_name] => South America
        )
)

私はPHPを初めて使用するため、この複雑な配列を並べ替える方法がわかりませんでした。http://in2.php.net/manual/en/function.array-multisort.phpに示すように、単純な多次元配列を並べ替える方法を知っています。

Answer 1

最悪のシナリオでは、独自のソート関数を作成し、usortを使用します。
それは実際にはこの種のもののために設計されています。

あなたの場合、あなたは合格$arr[$i]['countries']し、比較関数をに基づいてソートし$arr['growth']ます。

Answer 2

私は何年もの間、次の並べ替え機能を使用しています。

/**
 * sorting array of associative arrays - multiple row sorting using a closure
 * see also: the-art-of-web.com/php/sortarray/
 * @param array $data input-array
 * @param string|array $fields array-keys
 * @license Public Domain
 * @return array
 */
function sortArray( $data, $field )
{
    $field = (array) $field;
    uasort( $data, function($a, $b) use($field) {
        $retval = 0;
        foreach( $field as $fieldname )
        {
            if( $retval == 0 ) $retval = strnatcmp( $a[$fieldname], $b[$fieldname] );
        }
        return $retval;
    } );
    return $data;
}


// example call, sort by 'growth' first and by 'country_code' afterwards
// this would be equal to a MySQL 'ORDER BY `growth` ASC, `country_code` ASC'
foreach( $countryArray as &$item )
{
    $item['countries'] = sortArray( $item['countries'], array( 'growth', 'country_code' ) );
}