I would like to update my matplotlibplot with values calculated in each iteration of a for loop. The idea is that I can see in real time which values are calculated and watch the progress iteration by iteration as my script is running. I do not want to first iterate through the loop, store the values and then perform the plot.

Some sample code is here:

from itertools import count
import random

from matplotlib.animation import FuncAnimation
import matplotlib.pyplot as plt


def animate(i, x_vals, y_vals):
    plt.cla()
    plt.plot(x_vals, y_vals)

if __name__ == "__main__":
    x_vals = []
    y_vals = []
    fig = plt.figure()
    index = count()

    for i in range(10):
        print(i)
        x_vals.append(next(index))
        y_vals.append(random.randint(0, 10))
        ani = FuncAnimation(fig, animate, fargs=(x_vals, y_vals))
        plt.show()

Most of the examples I have seen online, deal with the case where everything for the animation is global variables, which I would like to avoid. When I use a debugger to step through my code line by line, the figure does appear and it is animated. When I just run the script without the debugger, the figure displays but nothing is plot and I can see that my loop doesn't progress past the first iteration, first waiting for the figure window to be closed and then continuing.

CodePudding user response：

You should never be using a loop when animating in matplotlib.

The animate function gets called automatically based on your interval.

Something like this should work

def animate(i, x=[], y=[]):
    plt.cla()
    x.append(i)
    y.append(random.randint(0, 10))
    plt.plot(x, y)


if __name__ == "__main__":
    fig = plt.figure()
    ani = FuncAnimation(fig, animate, interval=700)
    plt.show()