Why is Jupyter Notebook creating duplicate plots when making updating plots

Question

I'm trying to make plots in a Jupyter Notebook that update every second or so. Right now, I just have a simple code which is working:

%matplotlib inline
import time
import pylab as plt
import numpy as np
from IPython import display

for i in range(10):
    plt.close()
    a = np.random.randint(100,size=100)
    b = np.random.randint(100,size=100)

    fig, ax = plt.subplots(2,1)
    ax[0].plot(a)
    ax[0].set_title('A')
    ax[1].plot(b)
    ax[1].set_title('B')

    display.clear_output(wait=True)
    display.display(plt.gcf())
    time.sleep(1.0)

Which updated the plots I have created every second. However, at the end, there is an extra copy of the plots:

Why is it doing this? And how can I make this not happen? Thank you in advance.

Answer 1

The inline backend is set-up so that when each cell is finished executing, any matplotlib plot created in the cell will be displayed.

You are displaying your figure once using the display function, and then the figure is being displayed again automatically by the inline backend.

The easiest way to prevent this is to add plt.close() at the end of the code in your cell.