Matplotlib热图动画非常小

我试图在matplotlib中设置热图的动画，这在几个小时内第一次起作用，但图表非常小，如下所示。

我使用的代码如下：

import numpy as np
import matplotlib
matplotlib.use("Agg")
import matplotlib.pyplot as plt
import matplotlib.animation as animation
import xarray

Writer = animation.writers['ffmpeg']
writer = Writer(fps=15, metadata=dict(artist='Me'), bitrate=1800)

x = avar.values # Formatted as follows: [-32,-33,-34,-35,-36...]
y = avar.values # Formatted as follows: [150.2, 151.2, 153.2...]
z = np.array(a[var].values) # [[[24,22,18,23,24,24,25]

                        #   [18,25,23,22,21,19,26]
                        #   ...
                        #   [12,28,19,22,25,26,19]]
                        #  ...
                        #  [[8,4,16,12,22,24,23,8]
                        #   ...
                        #   [12,28,14,7,8,13,6,12]]]

fig = plt.figure()
ax = fig.add_subplot(len(x),len(y),1)
def plot(i):

data = z[i]
heatmap = ax.pcolor(x, y, data)

ani = animation.FuncAnimation(fig, plot, interval=1, frames=20)
ani.save('im.mp4', writer=writer)
我还应该提到尝试调用plt.subplots(x,y)导致控制台冻结的原因，5分钟后它仍然没有进展。