Python 3d scatterplot colormap issue

Question

I have four dimensional data (x, y, z displacements; and respective voltages) which I wish to plot in a 3d scatterplot in python. I\'ve gotten the 3d plot to render, but I w

Answer 1

ax.scatter can take a color parameter c which is a sequence (e.g. a list or an array) of scalars, and a cmap parameter to specify a color map. So to make the colors vary according to the magnitude of the voltages, you could define:

c = np.abs(v)

This makes positive and negative voltages have the same color. If instead you wished each color (positive or negative) to have its own color, you could just use c = v.

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For example,

import matplotlib.pyplot as plt
from mpl_toolkits.mplot3d import Axes3D
import numpy as np
x, y, z, v = (np.random.random((4,100))-0.5)*15
c = np.abs(v)

fig = plt.figure()
ax = fig.add_subplot(111, projection='3d')
cmhot = plt.get_cmap("hot")
cax = ax.scatter(x, y, z, v, s=50, c=c, cmap=cmhot)

plt.show()