php 数据分组

在PHP中，可以使用数组函数和循环来对数据进行分组。以下是一个示例代码，演示如何将数据按照指定的字段进行分组：

$data = [
    ['name' => 'Alice', 'age' => 25, 'city' => 'New York'],
    ['name' => 'Bob', 'age' => 30, 'city' => 'Los Angeles'],
    ['name' => 'Charlie', 'age' => 25, 'city' => 'New York'],
    ['name' => 'Dave', 'age' => 35, 'city' => 'San Francisco'],
    ['name' => 'Eve', 'age' => 30, 'city' => 'Los Angeles'],
];

$groupedData = [];

foreach ($data as $item) {
    $age = $item['age'];

    if (!isset($groupedData[$age])) {
        $groupedData[$age] = [];
    }

    $groupedData[$age][] = $item;
}

print_r($groupedData);

以上代码将根据age字段将数据分组。输出结果如下：

Array
(
    [25] => Array
        (
            [0] => Array
                (
                    [name] => Alice
                    [age] => 25
                    [city] => New York
                )

            [1] => Array
                (
                    [name] => Charlie
                    [age] => 25
                    [city] => New York
                )

        )

    [30] => Array
        (
            [0] => Array
                (
                    [name] => Bob
                    [age] => 30
                    [city] => Los Angeles
                )

            [1] => Array
                (
                    [name] => Eve
                    [age] => 30
                    [city] => Los Angeles
                )

        )

    [35] => Array
        (
            [0] => Array
                (
                    [name] => Dave
                    [age] => 35
                    [city] => San Francisco
                )

        )

)

可以看到，数据按照年龄分成了不同的组。每个组都是一个子数组，包含具有相同年龄的所有数据项。