按特定键过滤多维数组，创建子数组PHP？

<?php
// 原始多维数组
$students = array(
    array('name' => 'Alice', 'age' => 20, 'grade' => 'A'),
    array('name' => 'Bob', 'age' => 22, 'grade' => 'B'),
    array('name' => 'Charlie', 'age' => 19, 'grade' => 'A'),
    array('name' => 'David', 'age' => 21, 'grade' => 'C')
);

// 过滤条件：只保留年龄大于等于20的学生
$filteredStudents = array_filter($students, function($student) {
    return $student['age'] >= 20;
});

// 输出过滤后的结果
print_r($filteredStudents);
?>

Array
(
    [0] => Array
        (
            [name] => Alice
            [age] => 20
            [grade] => A
        )

    [1] => Array
        (
            [name] => Bob
            [age] => 22
            [grade] => B
        )

    [3] => Array
        (
            [name] => David
            [age] => 21
            [grade] => C
        )

)