PHP 数组分组函数在 Web 开发中的应用

$colors = ['red', 'green', 'blue', 'orange', 'yellow'];

// 按首字母分组
$grouped = group_by($colors, function ($item) {
    return $item[0];
});

print_r($grouped);

/**
输出：

Array
(
    [r] => Array
        (
            [0] => red
        )

    [g] => Array
        (
            [0] => green
        )

    [b] => Array
        (
            [0] => blue
        )

    [o] => Array
        (
            [0] => orange
        )

    [y] => Array
        (
            [0] => yellow
        )
)
**/

// 模拟用户数据
$users = [
    ['id' => 1, 'name' => 'John', 'gender' => 'male'],
    ['id' => 2, 'name' => 'Mary', 'gender' => 'female'],
    ['id' => 3, 'name' => 'Bob', 'gender' => 'male'],
    ['id' => 4, 'name' => 'Alice', 'gender' => 'female'],
];

// 按性别分组
$groupedUsers = group_by($users, 'gender');

// 打印分组后的用户数据
foreach ($groupedUsers as $gender => $users) {
    echo "**$gender:**" . PHP_EOL;
    foreach ($users as $user) {
        echo "{$user['name']} ({$user['id']})" . PHP_EOL;
    }
    echo PHP_EOL;
}

/**
输出：

**male:**
John (1)
Bob (3)

**female:**
Mary (2)
Alice (4)
**/