// seřazení produktů dle zařazení subkategorií
function woocommerce_get_product_category_of_subcategories( $category_slug ){
  $terms_html = array();
  $taxonomy = 'product_cat';
  $parent = get_term_by( 'slug', $category_slug, $taxonomy );
  $children_ids = get_term_children( $parent->term_id, $taxonomy );
  foreach($children_ids as $children_id){
        $term = get_term( $children_id, $taxonomy ); 
        $term_link = get_term_link( $term, $taxonomy ); 
        if ( is_wp_error( $term_link ) ) $term_link = '';
        $terms_html[] = '<a href="' . esc_url( $term_link ) . '" rel="tag" class="' . $term->slug . '">' . $term->name . '</a>';
  }
  return '<span class="subcategories-' . $category_slug . '">' . implode( ', ', $terms_html ) . '</span>';
}