Matplotlib python中圆柱体的颜色

如何在y=0.3的基础上用与圆柱体中部相同的颜色涂色

import numpy as np
import matplotlib.pyplot as plt
from mpl_toolkits.mplot3d import Axes3D                        
from mpl_toolkits.mplot3d import proj3d                     

def data_for_cylinder_along_z(center_x,center_y,radius,height_z):
    z = np.linspace(0, height_z, 200)
    theta = np.linspace(0, 2*np.pi, 200)
    theta_grid, z_grid=np.meshgrid(theta, z)
    x_grid = radius*np.cos(theta_grid) + center_x
    y_grid = radius*np.sin(theta_grid) + center_y
    return x_grid,y_grid,z_grid

fig = plt.figure(figsize=[6,5])
ax = fig.add_subplot(111, projection='3d')
ax.azim = -39   
ax.elev = 15    

Xc,Zc,Yc = data_for_cylinder_along_z(0,0,0.05,0.3)
ax.plot_surface(Xc, Yc, Zc, alpha=0.4, color = 'grey')
plt.show()

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为什么

y=0.3的底面
不是
z=0.3的顶面
？我是说右底面。