Dynamically update bar chart value labels in matplotlib animation using ax.bar

I am trying to dynamically update the bar chart value labels in an animated matplotlib chart. The toy code I am using is here:

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

fig = plt.figure()

x = [1,2,3,4,5]
y = [5,7,2,5,3]

ax1 = plt.subplot(2, 1, 1)
ax2 = plt.subplot(2, 1, 2)
data = np.column_stack([np.linspace(0, yi, 50) for yi in y])

rects = ax1.bar(x, data[0], color='c')
line, = ax2.plot(x, data[0], color='r')
ax1.set_ylim(0, max(y))
ax1.bar_label(rects, padding=1)
ax2.set_ylim(0, max(y))
def animate(i):
    for rect, yi in zip(rects, data[i]):
        rect.set_height(yi)
    ax1.bar_label(rects, padding=1)
    line.set_data(x, data[i])

anim = animation.FuncAnimation(fig, animate, frames=len(data), interval=40)
plt.show()

The value labels are being printed at each time step, but they remain on the plot.

How can I update the value labels with each step in the animation without having the old labels remain on the chart?

CodePudding user response：

You can recreate rects in each frame in clearing ax1:

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

fig = plt.figure()

x = [1,2,3,4,5]
y = [5,7,2,5,3]

ax1 = plt.subplot(2, 1, 1)
ax2 = plt.subplot(2, 1, 2)
data = np.column_stack([np.linspace(0, yi, 50) for yi in y])

ax1.set_ylim(0, max(y))
ax2.set_ylim(0, max(y))
line, = ax2.plot(x, [0] * len(x), color='r')


def animate(i):
    ax1.cla()
    ax1.set_ylim(0, max(y))
    rects = ax1.bar(x, data[i], color='c')
    ax1.bar_label(rects, padding=1)
    line.set_data(x, data[i])


anim = animation.FuncAnimation(fig, animate, frames=len(data), interval=40)
plt.show()