device_plot.py

#!/usr/bin/env python3

import argparse
from os import path
from platform import system

import matplotlib.animation as animation
import matplotlib.pyplot as plt
import numpy as np
from matplotlib import use
from rplidar import RPLidar

BAUDRATE: int = 115200
TIMEOUT: int = 1
DMAX: int = 4000
IMIN: int = 0
IMAX: int = 50


def update_line(num, iterator, line):
    scan = next(iterator)
    offsets = np.array([(np.radians(meas[1]), meas[2]) for meas in scan])
    line.set_offsets(offsets)
    intents = np.array([meas[0] for meas in scan])
    line.set_array(intents)
    return line


def run():
    if system() == 'Darwin':
        use('MacOSX')

    description = 'rplidar device plot'
    epilog = 'The author assumes no liability for any damage caused by use.'
    parser = argparse.ArgumentParser(prog='./device_plot.py', description=description, epilog=epilog)
    parser.add_argument('device', help="device path", type=str)
    args = parser.parse_args()
    dev_path = args.device

    if path.exists(dev_path):
        print('Found device : {0}'.format(dev_path))
        print('To stop - close the plot window')

        lidar = RPLidar(port=dev_path, baudrate=BAUDRATE, timeout=TIMEOUT)

        fig = plt.figure()
        title = 'RPLIDAR'
        fig.set_label(title)
        fig.canvas.manager.set_window_title(title)

        ax = plt.subplot(111, projection='polar')
        line = ax.scatter([0, 0], [0, 0], s=5, c=[IMIN, IMAX], cmap=plt.cm.Greys_r, lw=0)
        ax.set_title('360° scan result')
        ax.set_rmax(DMAX)
        ax.grid(True)

        iterator = lidar.iter_scans()
        ani = animation.FuncAnimation(fig, update_line, fargs=(iterator, line), interval=50)

        plt.show()
        lidar.stop()
        lidar.disconnect()
    else:
        print('[Error] Could not found device: {0}'.format(dev_path))


if __name__ == '__main__':
    run()