CODEWITHSUNDEEP
pythonmatplotlib
sunnydk
sunnydk

Reputation: 67

Pointing all arrows towards the origin in matplotlib 3D scatter

I have been trying to figure an easy way to define u,v,w of mpl_toolkits.mplot3d.Axes3D.quiver such that all the quivers (from all over the 3D scatter plot) are all pointing towards the origin. Many thanks for all help rendered!!

Upvotes: 0

Views: 1012

Answers (1)

William Miller
William Miller

Reputation: 10328

You can do this fairly easily by starting with unit-length quivers:

from mpl_toolkits.mplot3d import Axes3D

import matplotlib.pyplot as plt
import numpy as np

fig = plt.figure()
ax = fig.gca(projection='3d')

n = 25

# Generate some random data
x = (np.random.random(n) - 0.5) * 10
y = (np.random.random(n) - 0.5) * 10
z = (np.random.random(n) - 0.5) * 10

r = np.sqrt(np.power(x,2) + np.power(y,2) + np.power(z,2))

# Create unit-length quivers by dividing out the magnitude
u = - x / r
v = - y / r
w = - z / r

ax.quiver(x, y, z, u, v, w)
plt.show()

enter image description here

And then if you want quivers of a certain size or if you have an array of sizes you can simply multiply this in when creating u, v, and w:

sizes = np.random.random(n) * 4
u = -x / r * sizes
v = -y / r * sizes
w = -z / r * sizes

ax.quiver(x, y, z, u, v, w)
plt.show()

enter image description here

This should also support other methods of analytical sizing - provided you calculate the r vectors correctly.

Upvotes: 1

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