Combining scatter plot with surface plot

Question

How can I combine a 3D scatter plot with a 3D surface plot while keeping the surface plot transparent so that I can still see all the points?

Asked By: xelda_serve

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Source

Answer 1

To combine various types of plots in the same graph you should use the function

plt.hold(True).

The following code plots a 3D scatter plot with a 3D surface plot:

from mpl_toolkits.mplot3d import *
import matplotlib.pyplot as plt
import numpy as np
from random import random, seed
from matplotlib import cm


fig = plt.figure()
ax = fig.gca(projection='3d')               # to work in 3d
plt.hold(True)

x_surf=np.arange(0, 1, 0.01)                # generate a mesh
y_surf=np.arange(0, 1, 0.01)
x_surf, y_surf = np.meshgrid(x_surf, y_surf)
z_surf = np.sqrt(x_surf+y_surf)             # ex. function, which depends on x and y
ax.plot_surface(x_surf, y_surf, z_surf, cmap=cm.hot);    # plot a 3d surface plot

n = 100
seed(0)                                     # seed let us to have a reproducible set of random numbers
x=[random() for i in range(n)]              # generate n random points
y=[random() for i in range(n)]
z=[random() for i in range(n)]
ax.scatter(x, y, z);                        # plot a 3d scatter plot

ax.set_xlabel('x label')
ax.set_ylabel('y label')
ax.set_zlabel('z label')

plt.show()

result:

you can see some other examples with 3d plots here:
http://matplotlib.org/mpl_toolkits/mplot3d/tutorial.html

I’ve changed the colours of the surface plot from the default to a colormap “hot” in order to distinguish the colours of the two plots – now, it’s seen that the surface plot overrides the scatter plot, independently of the order…

EDIT: To fix that issue, it should be used transparency in the colormap of the surface plot; adding the code in:
Transparent colormap
and changing the line:

ax.plot_surface(x_surf, y_surf, z_surf, cmap=cm.hot);    # plot a 3d surface plot

to

ax.plot_surface(x_surf, y_surf, z_surf, cmap=theCM);

we get:

Answered By: sissi_luaty

Answer 2

Using siluaty’s example; instead of using transparency through the cmap=theCM command, you can adjust the alpha value. This may get you what you want?

ax.plot_surface(x_surf, y_surf, z_surf, cmap=cm.hot, alpha=0.2)

Answered By: StevilP

Answer 3

As others mentioned, if you want transparent 3d plot, just provide alpha argument:

  # elve, azim are custom viewpoint/angle
  ax = plt.axes(projection='3d', elev=35, azim=-125) 
  ax.plot_surface(x, y, z, alpha=0.7)
  ax.plot(scatter_x, scatter_y, scatter_z, 'b.', markersize=10, label='top')

This will give:

If you want to plot points on top of the 3d plot, use zorder. For example, the following code will generate:

  ax = plt.axes(projection='3d', elev=35, azim=-125)
  ax.plot_surface(x, y, z, cmap=plt.cm.coolwarm, linewidth=0.1, zorder=1)
  ax.plot(scatter_x, scatter_y, scatter_z, 'b.', markersize=10, label='top', zorder=4)

Answered By: Iman Mirzadeh

Combining scatter plot with surface plot

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