Return the values from a single column in the input array recursively

array_column_recursive.php

<?php

if (! function_exists('array_column_recursive')) {
    /**
     * Return the values from a single column in the input array recursively
     *
     * @param array           $array
     * @param int|string|null $columnKey
     * @param int|string|null $indexKey
     * @return array
     */
    function array_column_recursive(array $array, $columnKey, $indexKey = null): array
    {
        $result = array_column($array, $columnKey, $indexKey);

        foreach ($array as $value) {
            if (is_array($value)) {
                $recursive = array_column_recursive($value, $columnKey, $indexKey);

                $result = is_null($indexKey)
                    ? array_merge($result, $recursive)
                    : array_replace($result, $recursive);
            }
        }

        return $result;
    }
}