Matplotlib FuncAnimation only shows one frame

Question

I am trying to do an animation using the FuncAnimation module but my code only produces one frame. It looks like that it update the right thing (k) and it go on with the animation for the right amount of frames, but every frame shows the first image with k=0.

def plotheatmap(u_k, k):
    # Clear the current plot figure
    plt.clf()

    plt.title(f"Temperature at t = {k*dt:.3f} unit time")
    plt.xlabel("x")
    plt.ylabel("y")

    # This is to plot u_k (u at time-step k)
    plt.pcolormesh(u_k, cmap=plt.cm.jet, vmin=0, vmax=4)
    plt.colorbar()

def animate(k): 
    plotheatmap(convert(U)[k], k)


anim = animation.FuncAnimation(plt.figure(), animate, interval=200, frames=M+1)

Answer 1

Since you didn't provide a reproducible example, I'm going to generate random data, and you will adapt it to your case.

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


x = np.arange(-0.5, 10, 1)
y = np.arange(4.5, 11, 1)

fig, ax = plt.subplots()
ax.set_xlabel("x")
ax.set_ylabel("y")

def plotheatmap(k):
    z = np.random.rand(6, 10)
    # clear the previously added heatmaps
    ax.collections.clear()
    # add a new heatmap
    ax.pcolormesh(x, y, z)
    ax.set_title(f"Temperature at t = {k:.3f} unit time")

def animate(k): 
    plotheatmap(k)

M = 10
anim = FuncAnimation(fig, animate, interval=200, frames=M+1)