内核键上的PHP数组合并

I have two arrays like:

我有两个数组，如：

$a = [
    0 => [
        'price' => 5.5
    ],
    1 => [
        'price' => 6.0
    ],
    2 => [
        'price' => 6.2
    ],
    3 => [
        'price' => 6.5
    ],
];

$b = [
    0 => [
        'color' => 'RED'
    ],
    1 => [
        'color' => 'WHITE'
    ],
    2 => [
        'color' => 'BLUE'
    ],
    3 => [
        'color' => 'RED'
    ],
];
$a = [