Вывода любой части меню для wp_nav_menu — custom Walker class

Display a portion/ branch of the menu tree using wp_nav_menu()

Демо:

http://kadrs.ru/podbor-personala/galereya-specialistov

Сниппет:

add_filter( 'wp_nav_menu_objects', 'submenu_limit', 10, 2 );
function submenu_limit( $items, $args ) {
    if ( empty($args->submenu) )
        return $items;
    $parent_id = array_pop( wp_filter_object_list( $items, array( 'title' => $args->submenu ), 'and', 'ID' ) );
    $children  = submenu_get_children_ids( $parent_id, $items );
    foreach ( $items as $key => $item ) {
        if ( ! in_array( $item->ID, $children ) )
            unset($items[$key]);
    }
    return $items;
}
function submenu_get_children_ids( $id, $items ) {
    $ids = wp_filter_object_list( $items, array( 'menu_item_parent' => $id ), 'and', 'ID' );
    foreach ( $ids as $id ) {
        $ids = array_merge( $ids, submenu_get_children_ids( $id, $items ) );
    }
    return $ids;
}
// Usage:
$args = array(
    'menu'    => 'Menu Name',
    'submenu' => 'About Us',
);
wp_nav_menu( $args );

http://wordpress.stackexchange.com/questions/2802/display-a-portion-branch-of-the-menu-tree-using-wp-nav-menu/2809#2809

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