def iou(polygon_1,polygon_2):
        """
        Calculate intercept over union for shapely polygons.

        Args:
            polygon_1
            polygon_2

        Returns:
            intercept over union

        """
        area_intersection = polygon_1.intersection(polygon_2).area
        area_polygon_1_polygon_2 = polygon_1.union(polygon_2).area
        iou = area_intersection/(area_polygon_1_polygon_2) * 100
        return iou