How can i len() the Path.msg from path planing?

edit

The coding bolow get a waypoint from csv that the waypoint was saved time by time. I try to change calling way from get waypoint from csv to get realtime path. I not sure that i try the right way. I want to use pure pursuit for autonomous driving.

def read_waypoints(self):
        rospack = rospkg.RosPack()
        package_path=rospack.get_path('a_stars_pure_pursuit')
        filename=package_path+'/waypoints/waypoints_1.csv'

        with open(filename) as f:
            path_points = [tuple(line) for line in csv.reader(f)]

    self.path_points_x   = [float(point[0]) for point in path_points]
    self.path_points_y   = [float(point[1]) for point in path_points]
    self.path_points_w   = [float(point[2]) for point in path_points]

    #Initialize array of zeros with the same number of entries as the waypoint markers
    self.dist_arr= np.zeros(len(self.path_points_y))

I try this :

path_points_x = []
path_points_y = []
path_points_w = []
def read_waypoints(self):
    pose = PoseStamped() 
    for i in len(Path):
        self.path_points_x   = path_points_x.append([float(Path[i].pose.pose.position.x)])
        self.path_points_y   = path_points_y.append([float(Path[i].pose.pose.position.y)])
        self.path_points_w   = path_points_w.append([float(Path[i].pose.pose.orientation.w)])

    #Initialize array of zeros with the same number of entries as the waypoint markers
    self.dist_arr= np.zeros(len(self.path_points_y))

The error show they cannot len the Path.msg. Can we count the Path.msg?