Extract and Remap Columns from Array of Objects/Arrays

<?php
/**
 * Extracts a column from an array of arrays/objects and optionally renames the key.
 *
 * @param array $array The input array of arrays or objects.
 * @param string $columnKey The key or property to extract.
 * @param string|null $indexKey (Optional) The key to use for the new array's keys. If null, a simple list is returned.
 * @param string|null $newColumnKey (Optional) The new key name for the extracted column in the resulting associative array.
 * @return array The extracted column as a new array.
 */
function array_column_remapped(array $array, string $columnKey, ?string $indexKey = null, ?string $newColumnKey = null): array
{
    $result = [];
    foreach ($array as $item) {
        $value = is_array($item) ? ($item[$columnKey] ?? null) : ($item->$columnKey ?? null);
        $index = $indexKey ? (is_array($item) ? ($item[$indexKey] ?? null) : ($item->$indexKey ?? null)) : null;

        if ($newColumnKey) {
            $entry = [$newColumnKey => $value];
        } else {
            $entry = $value;
        }

        if ($index !== null) {
            $result[$index] = $entry;
        } else {
            $result[] = $entry;
        }
    }
    return $result;
}

// Example usage with arrays:
$users = [
    ['id' => 1, 'name' => 'Alice', 'email' => '[email protected]'],
    ['id' => 2, 'name' => 'Bob', 'email' => '[email protected]'],
    ['id' => 3, 'name' => 'Charlie', 'email' => '[email protected]']
];

// Extract 'email' as a simple list
$emails = array_column_remapped($users, 'email');
// Expected: ['[email protected]', '[email protected]', '[email protected]']
print_r($emails);

// Extract 'name' using 'id' as keys
$userNamesById = array_column_remapped($users, 'name', 'id');
// Expected: [1 => 'Alice', 2 => 'Bob', 3 => 'Charlie']
print_r($userNamesById);

// Extract 'email' and rename it to 'user_email', indexed by 'id'
$userEmailsRenamed = array_column_remapped($users, 'email', 'id', 'user_email');
// Expected: [1 => ['user_email' => '[email protected]'], 2 => ['user_email' => '[email protected]'], 3 => ['user_email' => '[email protected]']]
print_r($userEmailsRenamed);

// Example usage with objects:
class User { public $id; public $name; public $email; public function __construct($id, $name, $email) { $this->id = $id; $this->name = $name; $this->email = $email; } }
$userObjects = [
    new User(4, 'David', '[email protected]'),
    new User(5, 'Eve', '[email protected]')
];

$objectEmails = array_column_remapped($userObjects, 'email', 'id', 'email_address');
// Expected: [4 => ['email_address' => '[email protected]'], 5 => ['email_address' => '[email protected]']]
print_r($objectEmails);
?>