How can I update a plot without creating multiple figures?

Question

I am using Python 3.9 in Spyder and have a problem with plotting. Whenever I plot something, in the "Plot" Pane, a new plot pops up.

For my application, I want to update the plot very quickly but every time I plot the figure, a new figure appears in the "Plot" Pane and after 500 plots it gets very laggy. With hours of searching on the web, I have found no good way to do it.

Ideally, the plot contents should just be removed and not the figure or axes.

My code is as follows:

import matplotlib.pyplot as plt # Module for plotting data
import time # Module for acquiring times

for i in range(1,11):

    fig = plt.figure()
    ax = plt.axes(projection = '3d')
    
    ax.set_xlim(-10,10)
    ax.set_ylim(-10,10)
    ax.set_zlim(-10,10)
    
    ax.quiver(0,0,0,i,i,i)
    plt.show()
    time.sleep(0.1)

Its very straight forwards and easy, but all it produces is 10 individual plots in the "Plot" pane (I muted Inline Plotting). Preferably, I would have one plot which just updates, either in the "Plot" Pane of Spyder or as a seperate window.

score 1 · Answer 1 · edited May 25 '23 at 21:27

1

You can try something like this:

import matplotlib.pyplot as plt

fig = plt.figure()
ax = plt.axes(projection = '3d')

for i in range(1,11):
   
    ax.set_xlim(-10,10)
    ax.set_ylim(-10,10)
    ax.set_zlim(-10,10)
    ax.quiver(0,0,0,i,i,i)
    plt.draw()
    plt.pause(.01)
    ax.clear()

The plot will get updated every 0.01 seconds.

edited May 25 '23 at 21:27

Trenton McKinney

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answered May 25 '23 at 12:12

Pablo C

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I had to add "import matplotlib" and matplotlib.use('TkAgg')" in front of your code to make it work. But it works! Thanks a lot. – F F May 26 '23 at 13:53
On another note: How to close the figure? I've searched the internet for an hour, but I cant find a way to close the figure without having to force it to shut down. Its "not responding" after the last plot. – F F May 26 '23 at 14:15
@FF `plt.close()`? – Pablo C May 26 '23 at 14:18
Sorry, plt.close() does not do anything. – F F May 26 '23 at 14:20
@FF `plt.close(fig)`? – Pablo C May 26 '23 at 14:22

Trenton McKinney · Answer 2 · 2023-05-26T14:14:53.453

0

Updating an existing plot usually entails creating a matplotlib-animation.

As per this answer.

import matplotlib.animation as animation
import matplotlib.pyplot as plt

fig = plt.figure()
ax = fig.add_subplot(projection='3d')

def update(i):
    ax.clear()
    ax.set_xlim(-10, 10)
    ax.set_ylim(-10, 10)
    ax.set_zlim(-10, 10)
    ax.quiver(0, 0, 0, 10, 10, 10)
        
ani = animation.FuncAnimation(fig, update, frames=11, interval=1)

# this is not needed unless you want to save the file
# ani.save('quiver.gif', writer='pillow')

edited May 26 '23 at 14:14

answered May 25 '23 at 21:28

Trenton McKinney

56,955
33
144
158

Thanks! Unfortunately your code does not work in my Python... Just plain like you posted, it doesn't do anything besides plotting the last plot in the "Plot" Pane of Spyder. – F F May 26 '23 at 13:55

How can I update a plot without creating multiple figures?

2 Answers2