如何过滤关联数组？

Question

我必须处理重构,以减少PHP中的代码行数,以过滤关联数组.所以我在MySQL中选择DB,以获得一个关联数组.所以我的"对象"有一个类别和一个姓氏字段.

while ($row = mysqli_fetch_array($result)) {
        $array[] = $row['category'];
        $array[] = $row['Surname'];
   }

我想从这个数组中获取,就像许多其他子数组一样,按类别划分.我的意思是类别数组标识可能是:

$categories = array("A","B","C","D");

所以我想要的是为每个类别获取一个数组,其中包含该类别的所有姓氏.所以假设该方法有效,如下所示:

$arrayFiltered = method_filter($array_asso,"A");

最后我想要这样的东西:

    foreach ($categories as &$value) {
       $arrayFiltered = method_filter($array_asso,$value);
       my_method_which_needs_the_filtered_array($arrayFiltered);
}

预先感谢您的帮助.

Answer 1

中士的方法是最简单的。只是为了它，这里有一种方法array_filter()（以防万一你还必须有一个未过滤的数组）：

$array = [];
$categories = array("A","B","C","D");

while ($row = mysqli_fetch_array($result)) {
    $item = [
        'category' => $row['category'],
        'surname' => $row['Surname']
    ];

    $array[] = $item;
}

$categorized = [];

foreach ($categories as $category) {
    $categorized[$category] = array_filter($array, function($item) use ($category) {
        return $item['category'] == $category;
    });
}

这是不需要数据库连接的概念证明：

$categories = array("A","B","C","D");

$array = [
    ['category' => 'A', 'Surname' => 'A Name 1'],
    ['category' => 'A', 'Surname' => 'A Name 2'],
    ['category' => 'B', 'Surname' => 'B Name 1'],
    ['category' => 'B', 'Surname' => 'B Name 2'],
    ['category' => 'B', 'Surname' => 'B Name 3'],
    ['category' => 'C', 'Surname' => 'C Name'],
];

$categorized = [];

foreach ($categories as $category) {
    $categorized[$category] = array_filter($array, function($item) use ($category) {
        return $item['category'] == $category;
    });
}

print_r($categorized);

输出：

Array
(
    [A] => Array
        (
            [0] => Array
                (
                    [category] => A
                    [Surname] => A Name 1
                )

            [1] => Array
                (
                    [category] => A
                    [Surname] => A Name 2
                )

        )

    [B] => Array
        (
            [2] => Array
                (
                    [category] => B
                    [Surname] => B Name 1
                )

            [3] => Array
                (
                    [category] => B
                    [Surname] => B Name 2
                )

            [4] => Array
                (
                    [category] => B
                    [Surname] => B Name 3
                )

        )

    [C] => Array
        (
            [5] => Array
                (
                    [category] => C
                    [Surname] => C Name
                )

        )

    [D] => Array
        (
        )

)