Not able to plot real time graph using matplotlib

Question

I have written the following code with the help of online search. My intention here is to get a real time graph with time on x axis and some randomly generated value on y axis

import matplotlib.pyplot as plt
import matplotlib.animation as animation
import time
import numpy as np

fig = plt.figure()
ax1 = fig.add_subplot(1,1,1)

def animate(i):
    xar = []
    yar = []
    x,y = time.time(), np.random.rand()
    xar.append(x)
    yar.append(y)
    ax1.clear()
    ax1.plot(xar,yar)
ani = animation.FuncAnimation(fig, animate, interval=1000)
plt.show()

With the above code I just see the range of y axis changing continuously and the graph will not appear in the figure.

Jonas Adler · Accepted Answer · 2017-07-14 19:49:20Z

1

The problem is that you never update xvar and yvar. You can do that by moving the definitions of the lists outside the definition of animate.

import matplotlib.pyplot as plt
import matplotlib.animation as animation
import time
import numpy as np

fig = plt.figure()
ax1 = fig.add_subplot(1,1,1)
xar = []
yar = []

def animate(i):
    x,y = time.time(), np.random.rand()
    xar.append(x)
    yar.append(y)
    ax1.clear()
    ax1.plot(xar,yar)
ani = animation.FuncAnimation(fig, animate, interval=1000)
plt.show()

answered Jul 14, 2017 at 19:49

Jonas Adler

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