CODEWITHSUNDEEP
pythonmatplotlib3dsurfaceparametric-equations
DrBwts
DrBwts

Reputation: 3657

Matplotlib parametric surface plot unexpected results, why?

I am trying to plot an ellipsoid so, I thought I would amend the example code for a sphere from the matplotlib 3D plotting page.

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

fig = plt.figure()
ax = fig.add_subplot(111, projection='3d')

# Ellipsoid
u = np.linspace(-np.pi/2.0,np.pi/2.0,100)
v = np.linspace(-np.pi,np.pi,100)
x = 10 * np.outer(np.cos(u), np.cos(v))
y = 10 * np.outer(np.cos(u), np.sin(v))
z = 10 * np.outer(np.ones(np.size(u)), np.sin(v))


# Sphere
#u = np.linspace(0, 2 * np.pi, 100)
#v = np.linspace(0, np.pi, 100)
#x = 10 * np.outer(np.cos(u), np.sin(v))
#y = 10 * np.outer(np.sin(u), np.sin(v))
#z = 10 * np.outer(np.ones(np.size(u)), np.cos(v))

ax.plot_surface(x, y, z,  rstride=4, cstride=4, cmap = cm.copper)
ax.set_xlabel('x-axis')
ax.set_ylabel('y-axis')
ax.set_zlabel('z-axis')
plt.show()

If you run the code you will see that the plot returns an aesthetically pleasing half inside out boat like surface but sadly not an ellipsoid.

Have included the sphere code (commented out) for comparison.

Is there something obvious here that I'm missing?

Upvotes: 2

Views: 1188

Answers (1)

hitzg
hitzg

Reputation: 12701

Why did you change the parametrization? Starting with the sphere as an example, you only have to change the semi-axis lengths:

# Ellipsoid
u = np.linspace(0, 2.*np.pi, 100)
v = np.linspace(0, np.pi, 100)
x = 60 * np.outer(np.cos(u), np.sin(v))
y = 20 * np.outer(np.sin(u), np.sin(v))
z = 10 * np.outer(np.ones(np.size(u)), np.cos(v))

Upvotes: 2

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