How to update values from serial port in matplotli

问题:

I've been trying to plot serial data from an arduino in real-time using matplotlib's animation function. The data comes from a ntc temperature sensor. The plot I was able to get displays a sigle line all the time, and the line is only translated up or down as the teperature changes. I'd like to know what can I do to view the curves representing the changes in the plot. Here´s the code:

import serial
from matplotlib import pyplot as plt
from matplotlib import animation
import numpy as np

arduino = serial.Serial('COM3', 9600)

fig = plt.figure()
ax = plt.axes(xlim=(0, 10), ylim=(10, 40))
line, = ax.plot([], [], lw=2)

def init():
    line.set_data([], [])
    return line,

def animate(i):
    x = np.linspace(0, 10, 1000)
    y = arduino.readline()
    line.set_data(x, y)
    return line,

anim = animation.FuncAnimation(fig, animate, init_func=init, frames=200, interval=20,        blit=False)

plt.show()

回答1:

You are setting the y-data to be a single point (0, y). You want to do something like:

max_points = 50
# fill initial artist with nans (so nothing draws)
line, = ax.plot(np.arange(max_points), 
                np.ones(max_points, dtype=np.float)*np.nan, 
                lw=2)
def init():
    return line,

def animate(i):
    y = arduino.readline()  # I assume this 
    old_y = line.get_ydata()  # grab current data
    new_y = np.r_[old_y[1:], y]  # stick new data on end of old data
    line.set_ydata(new_y)        # set the new ydata
    return line,