def _tuple_from_str(bbox):
        """ Parses a string of numbers separated by any combination of commas and spaces

        :param bbox: e.g. str of the form `min_x ,min_y  max_x, max_y`
        :return: tuple (min_x,min_y,max_x,max_y)
        """
        return tuple([float(s) for s in bbox.replace(',', ' ').split() if s])