python - Can you plot live data in matplotlib?

Question

I'm reading data from a socket in one thread and would like to plot and update the plot as new data arrives. I coded up a small prototype to simulate things but it doesn't work:

import pylab
import time
import threading
import random

data = []

# This just simulates reading from a socket.
def data_listener():
    while True:
        time.sleep(1)
        data.append(random.random())

if __name__ == '__main__':
    thread = threading.Thread(target=data_listener)
    thread.daemon = True
    thread.start()

    pylab.figure()

    while True:
        time.sleep(1)
        pylab.plot(data)
        pylab.show() # This blocks :(

Answer 1

import matplotlib.pyplot as plt
import time
import threading
import random

data = []

# This just simulates reading from a socket.
def data_listener():
    while True:
        time.sleep(1)
        data.append(random.random())

if __name__ == '__main__':
    thread = threading.Thread(target=data_listener)
    thread.daemon = True
    thread.start()
    #
    # initialize figure
    plt.figure() 
    ln, = plt.plot([])
    plt.ion()
    plt.show()
    while True:
        plt.pause(1)
        ln.set_xdata(range(len(data)))
        ln.set_ydata(data)
        plt.draw()

If you want to go really fast, you should look into blitting.