mpl_toolkits.mplot3d 3D图形绘制

import numpy as np
import matplotlib.pyplot as plt
from mpl_toolkits.mplot3d import Axes3D

fig=plt.figure()
ax=Axes3D(fig)
x=np.arange(-4,4,0.25)
y=np.arange(-4,4,0.25)
X,Y=np.meshgrid(x,y)
Z=np.sin(np.sqrt(x2+y2))
ax.plot_surface(X,Y,Z,rstride=1,cstride=1,cmap='rainbow')
plt.show()

代码报错 Argument Z must be 2-dimensional.

import numpy as np
import matplotlib.pyplot as plt
from mpl_toolkits.mplot3d import Axes3D
 
fig = plt.figure()
ax = Axes3D(fig)
X = np.arange(-4, 4, 0.25)
Y = np.arange(-4, 4, 0.25)
X, Y = np.meshgrid(X, Y)
R = np.sqrt(X**2 + Y**2)
Z = np.sin(R)
 
ax.plot_surface(X, Y, Z, rstride=1, cstride=1, cmap=plt.cm.hot)
ax.contourf(X, Y, Z, zdir='z', offset=-2, cmap=plt.cm.hot)
ax.set_zlim(-2,2)
 
# savefig('../figures/plot3d_ex.png',dpi=48)
plt.show()