How Can I Efficiently Search for Key-Value Pairs in Multidimensional PHP Arrays?

Recursive Search for Key-Value Pairs in Multidimensional PHP Arrays

Searching for specific key-value pairs within a multidimensional array can be cumbersome. If the array depth is variable, finding a fast and efficient solution is essential.

Recursive Search Function

The following PHP function employs recursion to traverse the array recursively, comparing values for a given key:

function search($array, $key, $value)
{
    $results = array();

    if (is_array($array)) {
        if (isset($array[$key]) && $array[$key] == $value) {
            $results[] = $array;
        }

        foreach ($array as $subarray) {
            $results = array_merge($results, search($subarray, $key, $value));
        }
    }

    return $results;
}

Example Usage

Consider the following sample array:

$arr = array(
    0 => array('id' => 1, 'name' => 'cat 1'),
    1 => array('id' => 2, 'name' => 'cat 2'),
    2 => array('id' => 3, 'name' => 'cat 1')
);

To find all subarrays with key 'name' and value 'cat 1', we use:

print_r(search($arr, 'name', 'cat 1'));

Output:

Array
(
    [0] => Array
        (
            [id] => 1
            [name] => cat 1
        )

    [1] => Array
        (
            [id] => 3
            [name] => cat 1
        )

)

Efficiency Considerations

For improved efficiency, especially for large arrays, consider using a recursive function that passes results by reference. By sharing a single temporary $results array, performance can be significantly enhanced:

function search_r($array, $key, $value, &$results)
{
    if (!is_array($array)) {
        return;
    }

    if (isset($array[$key]) && $array[$key] == $value) {
        $results[] = $array;
    }

    foreach ($array as $subarray) {
        search_r($subarray, $key, $value, $results);
    }
}

The above is the detailed content of How Can I Efficiently Search for Key-Value Pairs in Multidimensional PHP Arrays?. For more information, please follow other related articles on the PHP Chinese website!