使用`array_map`和array_walk_recursive`转换和重组多维数组

array_map用于创建新数组并转换嵌套数据，需手动递归处理多维结构；array_walk_recursive用于直接修改叶节点值且支持键访问，自动深入到最底层。1. 使用array_map（配合递归函数）可对多维数组进行不可变转换，适用于需要返回新数组的场景；2. 使用array_walk_recursive可原地修改字符串、数值等叶节点，适合执行日志记录、数据清洗等副作用操作；3. 当需同时调整结构与值时，可先递归重命名或重组键，再用array_walk_recursive处理值；4. 核心区别在于array_map返回新数组而array_walk_recursive修改原数组，选择应基于是否需要保留原始数据。

When working with multidimensional arrays in PHP, you often need to transform or restructure nested data—whether it’s sanitizing input, modifying values, renaming keys, or flattening structures. Two powerful functions that help with this are array_map and array_walk_recursive. While they may seem similar at first glance, they serve different purposes and are best used in specific scenarios.

Here’s how to effectively use both to manipulate multidimensional arrays.

Using array_map for Transforming Nested Arrays

array_map applies a callback function to the elements of one or more arrays and returns a new array with the transformed values. When dealing with multidimensional arrays, you typically need to apply array_map recursively to reach deeper levels.

Example: Increment All Numeric Values in a Nested Array

function deep_map($callback, $array) {
    $result = [];
    foreach ($array as $key => $value) {
        if (is_array($value)) {
            $result[$key] = deep_map($callback, $value); // Recurse into sub-arrays
        } else {
            $result[$key] = $callback($value);
        }
    }
    return $result;
}

$data = [
    'user1' => ['age' => 25, 'score' => 88],
    'user2' => ['age' => 30, 'score' => 92],
];

$incremented = deep_map(function($item) {
    return is_numeric($item) ? $item   1 : $item;
}, $data);

print_r($incremented);

Output:

Array
(
    [user1] => Array
        (
            [age] => 26
            [score] => 89
        )
    [user2] => Array
        (
            [age] => 31
            [score] => 93
        )
)

✅ Use array_map (or a recursive wrapper) when you want to return a new transformed array without modifying the original.

Using array_walk_recursive for In-Place Modification

array_walk_recursive walks through every leaf node (non-array element) in a multidimensional array and applies a callback. It’s ideal when you want to modify values directly or perform operations like validation or logging.

Unlike array_map, it doesn’t return a new array—you modify values by reference.

Example: Convert All Strings to Uppercase

$data = [
    'product' => [
        'name' => 'laptop',
        'category' => 'electronics',
        'tags' => ['gaming', 'portable']
    ],
    'location' => 'warehouse a'
];

array_walk_recursive($data, function(&$value, $key) {
    if (is_string($value)) {
        $value = strtoupper($value);
    }
});

print_r($data);

Output:

Array
(
    [product] => Array
        (
            [name] => LAPTOP
            [category] => ELECTRONICS
            [tags] => Array
                (
                    [0] => GAMING
                    [1] => PORTABLE
                )
        )
    [location] => WAREHOUSE A
)

✅ Use array_walk_recursive when you want to modify leaf values in place or perform side effects (e.g., logging, validation).

Key Differences Summary

When to Combine Both?

Sometimes you need structural changes and deep value transformation. In such cases, combining both approaches makes sense.

For example, renaming keys recursively while modifying values:

function deep_transform(&$array) {
    foreach ($array as $key => $value) {
        // Rename keys
        if ($key === 'score') {
            $array['grade'] = $value;
            unset($array[$key]);
        }

        // Recurse into sub-arrays
        if (is_array($value)) {
            deep_transform($array[$key]);
        }
    }

    // Now modify scalar values
    array_walk_recursive($array, function(&$val) {
        if (is_string($val)) {
            $val = trim($val);
        }
    });
}

This hybrid approach gives full control over both structure and content.

Final Notes

• array_map is functional—it returns new data. Great for immutability.
• array_walk_recursive is imperative—it works on existing data. Efficient for bulk updates.
• Always consider whether you need a new array or can modify in place.
• Be cautious with references (&$value) to avoid unintended side effects.

Basically, choose based on your goal: transform → array_map, modify → array_walk_recursive.

以上是使用`array_map`和array_walk_recursive`转换和重组多维数组的详细内容。更多信息请关注PHP中文网其他相关文章！