组数组项通过键值添加与分组值的关联元素

Question

the以下数组：

$a = [
    "category" => "Music", 
    "items" => [
        ["ID" => "1", "start_date" => "2018-11-20", "end_date" => "2018-11-28"],
        ["ID" => "2", "start_date" => "2018-11-22", "end_date" => "2018-11-28"],
        ["ID" => "3", "start_date" => "2018-11-26", "end_date" => "2018-11-30"],
        ["ID" => "4", "start_date" => "2018-11-27", "end_date" => "2018-11-31"],
        ["ID" => "4", "start_date" => "2018-11-29", "end_date" => "2018-11-31"]
    ]
];

我想通过

end_date

end_dateend_date

来“分组”阵列，但不使用

array(
    "category" => "Music",
    "items" => array(
        array(
            "date" => "2018-11-28",
            array("ID" => "1", "start_date" => "2018-11-20", "end_date" => "2018-11-28"),
            array("ID" => "2", "start_date" => "2018-11-22", "end_date" => "2018-11-28"),
        ),
        array(
            "date" => "2018-11-30",
            array("ID" => "3", "start_date" => "2018-11-26", "end_date" => "2018-11-30")
        ),
        array(
            "date" => "2018-11-31",
            array("ID" => "4", "start_date" => "2018-11-27", "end_date" => "2018-11-31"),
            array("ID" => "4", "start_date" => "2018-11-29", "end_date" => "2018-11-31")
        )
    )
);

作为键，就像我在其他posts或forums

中所看到的那样，而是通过将

$a = array("category" => "Music", 
        "items" => array(
            array("ID" => "1", "start_date" => "2018-11-20", "end_date" => "2018-11-28"),
            array("ID" => "2", "start_date" => "2018-11-22", "end_date" => "2018-11-28"),
            array("ID" => "3", "start_date" => "2018-11-26", "end_date" => "2018-11-30"),
            array("ID" => "4", "start_date" => "2018-11-27", "end_date" => "2018-11-31"),
            array("ID" => "4", "start_date" => "2018-11-29", "end_date" => "2018-11-31")
        )
);

foreach($a['items'] as $item){
    $new[$item['end_date']]['date'] = $item['end_date'];
    $new[$item['end_date']][] = $item;
}
$res = $a;
unset($res['items']);
$res['items'] = array_values($new);


var_dump($res);

的值添加为一个值一个新键 因此，预期的结果将是：

array(2) {
  ["category"]=>
  string(5) "Music"
  ["items"]=>
  array(3) {
    [0]=>
    array(3) {
      ["date"]=>
      string(10) "2018-11-28"
      [0]=>
      array(3) {
        ["ID"]=>
        string(1) "1"
        ["start_date"]=>
        string(10) "2018-11-20"
        ["end_date"]=>
        string(10) "2018-11-28"
      }
      [1]=>
      array(3) {
        ["ID"]=>
        string(1) "2"
        ["start_date"]=>
        string(10) "2018-11-22"
        ["end_date"]=>
        string(10) "2018-11-28"
      }
    }
    [1]=>
    array(2) {
      ["date"]=>
      string(10) "2018-11-30"
      [0]=>
      array(3) {
        ["ID"]=>
        string(1) "3"
        ["start_date"]=>
        string(10) "2018-11-26"
        ["end_date"]=>
        string(10) "2018-11-30"
      }
    }
    [2]=>
    array(3) {
      ["date"]=>
      string(10) "2018-11-31"
      [0]=>
      array(3) {
        ["ID"]=>
        string(1) "4"
        ["start_date"]=>
        string(10) "2018-11-27"
        ["end_date"]=>
        string(10) "2018-11-31"
      }
      [1]=>
      array(3) {
        ["ID"]=>
        string(1) "4"
        ["start_date"]=>
        string(10) "2018-11-29"
        ["end_date"]=>
        string(10) "2018-11-31"
      }
    }
  }
}

Answer 1

loop阵列并构建一个临时关联数组，将结束日期作为键。 然后复制原始数组并取消设置“项目”并添加新的临时数组值。

items

输出：$array['items']

Https：//3v4l.org/fokl7

您可以使用功能风格的编程来分组和重新索引

Answer 2

子阵列，而无需声明全球空间中的任何临时变量。

当您迭代每一行时，请使用临时键进行分组并将行推入各自组。 完成分组后，将数据重新索引。

代码：（

demo

）

$array = [
    "category" => "Music", 
    "items" => [
        ["ID" => "1", "start_date" => "2018-11-20", "end_date" => "2018-11-28"],
        ["ID" => "2", "start_date" => "2018-11-22", "end_date" => "2018-11-28"],
        ["ID" => "3", "start_date" => "2018-11-26", "end_date" => "2018-11-30"],
        ["ID" => "4", "start_date" => "2018-11-27", "end_date" => "2018-11-31"],
        ["ID" => "4", "start_date" => "2018-11-29", "end_date" => "2018-11-31"]
    ]
];

$array["items"] = array_values(
    array_reduce(
        $array["items"],
        function ($carry, $row) {
            $carry[$row["end_date"]]["data"] = $row["end_date"];
            $carry[$row["end_date"]][] = $row;
            return $carry;
        }
    )
);
var_export($array);