python-can 的实时波形

Question

我正在尝试使用 python-can 和 matplotlib 库绘制 can-data。我有一个关于如何使用 matplotlib 绘制实时数据的基本示例：

import numpy as np
import matplotlib.pyplot as plt

plt.axis([0, 10, 0, 1])


for i in range(10):
    y = np.random.random()
    plt.scatter(i, y)
    # plt.pause(0.05)
    plt.draw()

plt.show()

我使用了一个基本的 python-can 示例并添加了 matplotlib：

import sys
import argparse
import socket
from datetime import datetime

import can
from can import Bus, BusState, Logger
import numpy as np
import matplotlib.pyplot as plt



def main():

    plt.axis([0, 10, 0, 1])

    bus = Bus(bustype ='pcan')
    i = 0

    print(f"Connected to {bus.__class__.__name__}: {bus.channel_info}")
    print(f"Can Logger (Started on {datetime.now()})")

    plt.show()

    try:
        while True:
            msg = bus.recv(1)
            if msg is not None:
                y = np.random.random()
                plt.scatter(i, y)
                plt.draw()
                i += 1
                print('Message id {id}'.format(id=msg.arbitration_id))

    except KeyboardInterrupt:
        pass
    finally:
        plt.show()
        bus.shutdown()


if __name__ == "__main__":
    main()

然而，一旦我添加了 plt 命令，脚本就会停止工作，它不再输出打印语句。当我对其进行调试并手动执行时，它会起作用。我做错了什么吗？有没有更好的方法来解决这个问题？我没有设置 matplotlib，只是绘制某些内容的最快方法 :)

Answer 1

我找到了一个使用 blit 函数的有效解决方案，它还不完美，但它是一个很好的起点：

from datetime import datetime
import can
from can import Bus, BusState, Logger
import numpy as np
import matplotlib.pyplot as plt
import struct



def main():
    bus = Bus(bustype ='pcan')
    i = 0

    print(f"Connected to {bus.__class__.__name__}: {bus.channel_info}")
    print(f"Can Logger (Started on {datetime.now()})")

    x = np.linspace(0, 1000, num=1000)
    y = np.zeros(1000)

    fig = plt.figure()
    ax1 = fig.add_subplot(1, 1, 1)
    line, = ax1.plot([], lw=3)
    text = ax1.text(0.8, 0.5, "")

    ax1.set_xlim(x.min(), x.max())
    ax1.set_ylim([-10, 10])

    fig.canvas.draw()  # note that the first draw comes before setting data

    ax2background = fig.canvas.copy_from_bbox(ax1.bbox)

    plt.show(block=False)
    k = 0


    try:
        while True:
            msg = bus.recv(1)
            if msg is not None:
                y = np.roll(y, 1)
                value = struct.unpack('f', msg.data)
                y[0] = np.int8(value)
                line.set_data(x, y)
                fig.canvas.restore_region(ax2background)
                ax1.draw_artist(line)
                ax1.draw_artist(text)
                fig.canvas.blit(ax1.bbox)
                fig.canvas.flush_events()
                # print('Message data {data}, value {value}, counter {counter}'.format(data=msg.data, value=value, counter=k))
                k += 1
                if k > 100:
                    k = 0

    except KeyboardInterrupt:
        pass
    finally:
        plt.show()
        bus.shutdown()


if __name__ == "__main__":
    main()

该脚本假定 can 消息在前四个 uint8 上携带一个浮点数并仅绘制它。

python-can 的实时波形

Live waveform with python-can

python

matplotlib

python-can