php多维数组排序问题

Question

我有一个复杂的多维数组。结构是这样的

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
        )
)

我想对它们进行排序（可能使用

array_multisort

），以便根据

growth

（从高到低的第一个）进行排序

这样排序后的数组就是

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
        )
)

我是 PHP 新手，所以我不知道如何对这个复杂的数组进行排序。我知道如何对简单的多维数组进行排序，如https://www.php.net/manual/en/function.array-multisort.php

所示

Answer 1

最坏的情况，你创建自己的排序函数并使用 usort。
它实际上是为这类事情而设计的。

在您的情况下，您将传递

$arr[$i]['countries']

并让比较函数基于

$arr['growth']

进行排序。

Answer 2

我已经使用以下排序功能多年了：

/**
 * 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' ) );
}

Answer 3

通过

foreach()

循环，使用数组解构语法通过引用修改国家/地区数据。在循环体中，调用

usort()

并按降序增长对子数组行进行排序。

代码：（演示）

foreach ($array as ['countries' => &$countries]) {
    usort($countries, fn($a, $b) => $b['growth'] <=> $a['growth']);
}
var_export($array);

---

可以使用

array_map()

对相同的技术进行功能样式设置，以生成数据的新变异副本。

代码：（演示）

var_export(
    array_map(
        function ($set) {
            usort($set['countries'], fn($a, $b) => $b['growth'] <=> $a['growth']);
            return $set;
        },
        $array
    )
);