按键的子项数对数组进行排序答案

【问题标题】：sort array by number of child of a key按键的子项数对数组进行排序
【发布时间】：2022-01-13 19:14:11
【问题描述】：

我有这样的东西来检查用户与其他人相比有多少相同的联系人，所以我将它保存在重复号码下。我想问一下有没有通过计算“duplicate_number”中的孩子数量来排序？在 PHP 中？

         {
            "user_id": 134,
            "duplicate_number": [
                {
                    "contact_name": "A",
                    "contact_no": "2341211",
                    "compared_name": "B"
                },
                {
                    "contact_name": "C",
                    "contact_no": "0236232",
                    "compared_name": "D"
                },
                {
                    "contact_name": "E",
                    "contact_no": "32326",
                    "compared_name": "F"
                }
            ]
        },
        {
            "user_id": 119,
            "duplicate_number": []
        },
        {
            "user_id": 108,
            "duplicate_number": [
                {
                    "contact_name": "G",
                    "contact_no": "053183",
                    "compared_name": "H"
                }
            ]
        },

【问题讨论】：

标签： php arrays sorting

【解决方案1】：

您可以为此使用usort，并基于duplicate_number 列表中的项目数，例如：

$list = [ 
    [
        "user_id" => 134,
        "duplicate_number" => [
            [ "contact_name"=> "A", "contact_no" => "2341211","compared_name" => "B" ],
            [ "contact_name" => "C", "contact_no" => "0236232", "compared_name" => "D" ],
            [ "contact_name" => "E", "contact_no" => "32326", "compared_name" => "F" ]
        ]
    ],
    [
        "user_id"=> 119,
        "duplicate_number"=> []
    ],
    [
        "user_id"=> 108,
        "duplicate_number"=> [
            [ "contact_name"=> "G", "contact_no"=> "053183", "compared_name"=> "H" ]
        ]
    ]
];

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

usort( $list, 'cmp' );
print_r( $list );

【讨论】：