How to draw sphere with arrow pointing from sphere in matplotlib-CodePudding

I try to draw a sphere to represent a qubit using matplotlib

import numpy as np 
import matplotlib.pyplot as plt
theta = [0, np.pi]
phi = [0, 2* np.pi]
N=100
theta_array = np.linspace(theta[0], theta[1], N)
phi_array = np.linspace(phi[0], phi[1], N)
theta_grid, phi_grid = np.meshgrid(theta_array,phi_array)

x = np.sin(theta_grid) * np.cos(phi_grid)
y = np.sin(theta_grid) * np.sin(phi_grid)
z = np.cos(theta_grid)

fig = plt.figure(figsize=(6,6))
ax = fig.gca(projection='3d')
ax.plot_surface(x, y, z, rstride=1, cstride=1, shade=False,linewidth=0)
plt.show()

I want to add tube arrows on the sphere with directions parallel with xyz axis, like this:

I am not an expert in matplotlib, so it's seem pretty tough to me. Can anyone help me? thanks in advance!

CodePudding user response：

You can use the quiver function to to what you want. See code below:

import numpy as np 
import matplotlib.pyplot as plt

theta = [0, np.pi]
phi = [0, 2* np.pi]
N=100
theta_array = np.linspace(theta[0], theta[1], N)
phi_array = np.linspace(phi[0], phi[1], N)
theta_grid, phi_grid = np.meshgrid(theta_array,phi_array)

x = np.sin(theta_grid) * np.cos(phi_grid)
y = np.sin(theta_grid) * np.sin(phi_grid)
z = np.cos(theta_grid)

fig = plt.figure(figsize=(6,6))
ax = fig.gca(projection='3d')
ax.view_init(azim=60)
ax.plot_surface(x, y, z, rstride=1, cstride=1, shade=False,linewidth=0)

#Set up arrows

ax.quiver(1,0,0,1,0,0,color = 'k', alpha = .8, lw = 3) #x arrow
ax.quiver(0,1,0,0,1,0,color = 'k', alpha = .8, lw = 3)#y arrow
ax.quiver(0,0,1,0,0,1,color = 'k', alpha = .8, lw = 3)#z arrow

plt.show()

And the output gives: