Set :: classicExtract（）CakePHP 2.x Hash :: alternative

I have an array like this:

我有一个像这样的数组：

$array = array(
    1234 => array(
        'title' => 'TitleA',
        'extra' => array(
            45 => 'SubA',
            54 => 'SubB',
        ),
        // More irrelevant data
    ),
    2345 => array(
        'title' => 'TitleB',
        'extra' => array(
            89 => 'SubC',
            98 => 'SubD',
        ),
        // More irrelevant data
    ),
);
$arr