MatPlotLib's ion() and draw() not working

Adapted for your case from : Python realtime plotting

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

fig = plt.figure()
ax = fig.add_subplot(111)

# some X and Y data
x = [0]
y = [0]

li, = ax.plot(x, y,'o')

# draw and show it
fig.canvas.draw()
plt.show(block=False)

# loop to update the data
for i in range(100):
    try:
        x.append(i)
        y.append(i)

        # set the new data
        li.set_xdata(x)
        li.set_ydata(y)

        ax.relim() 
        ax.autoscale_view(True,True,True) 

        fig.canvas.draw()

        time.sleep(0.01)
    except KeyboardInterrupt:
        plt.close('all')
        break

Hey I was having the same problem, I checked other questions and my issue was solved when I plugged a pause into my solution. Here's some example code that worked for me.

import matplotlib.pyplot as plt
import numpy as np
plt.ion()
x = np.arange(0, 4*np.pi, 0.1)
y = [np.sin(i) for i in x]
plt.plot(x, y, 'g-', linewidth=1.5, markersize=4)
plt.pause(0.0001)         
plt.plot(x, [i**2 for i in y], 'g-', linewidth=1.5, markersize=4)
plt.pause(0.0001)
plt.plot(x, [i**2*i+0.25 for i in y], 'r-', linewidth=1.5, markersize=4) 
plt.pause(0.0001)

The solution was posted here: Matplotlib ion() and subprocesses

This solution example has worked for me on multiple machines. Try adjusting plt.pause(...)

import matplotlib.pyplot as plt
import numpy as np

F = lambda x: np.sin(2*x)

plt.ion()    
x = np.linspace(0, 1, 200)
plt.plot(x, F(x))


for i in range(100):
    if 'ax' in globals(): ax.remove()
    newx = np.random.choice(x, size = 10)
    ax = plt.scatter(newx, F(newx))
    plt.pause(0.05)

plt.ioff()
plt.show()