python中如何画三维的图形？

import numpy as np

import matplotlib.pyplot as plt

from matplotlib import cm

from mpl_toolkits.mplot3d import Axes3D

X = np.arange(-5, 5, 0.25)

Y = np.arange(-5, 5, 0.25)

X, Y = np.meshgrid(X, Y)

R = np.sqrt(X**2 + Y**2)

Z = np.sin(R)

fig = plt.figure()

ax = Axes3D(fig)

surf=ax.plot_surface(X, Y, Z, rstride=1, cstride=1, cmap=cm.viridis)

# Add a color bar which maps values to colors.

fig.colorbar(surf, shrink=0.5, aspect=5)

plt.show()