Woocommerce checkout form - Reorder billing fields

functions.php

/*
 * Reorder Billing Field
*/
add_filter( 'woocommerce_checkout_fields', 'reorder_billing_fields');

function reorder_billing_fields($fields) {

    $order = array(
        'billing_first_name',
        'billing_last_name',
        'billing_company',
        'billing_tongbian', //this is a custom field, we added this before, seperately
        'billing_address_1',
        'billing_email',
        'billing_phone'

    );
    foreach($order as $field)
    {
        $ordered_fields[$field] = $fields['billing'][$field];
    }

    $fields['billing'] = $ordered_fields;
    return $fields;

}