def get_center(self):
        """
        Return (x,y) coordinate of central point
        """
        dist = self.get_distance()
        diff = self.get_diff()
        direction = diff / dist

        center_x = self.p2_x + (dist * 0.5) * direction[0]
        center_y = self.p2_y + (dist * 0.5) * direction[1]

        return np.array([center_x, center_y])