How To Obtain 3d Colored Surface Via Python?

April 14, 2024 Post a Comment

How to obtain the following surface via Matplotlib? It is easy in matlab via: mesh(peaks) It seems matplotlib does not have an exact counterpart of mesh in matlab. the Wireframe p

Solution 1:

While answering another question I found that you can easily do this using plot_surface to produce a color mapped surface, and then exchanging face and edge colors:

surf = ax.plot_surface(X, Y, Z, rstride=2, cstride=2, shade=False, cmap="jet", linewidth=1)
draw()
surf.set_edgecolors(surf.to_rgba(surf._A))
surf.set_facecolors("white")
show()

produces

The disadvantage this solution has over the other one is that the edges do not have smooth, per-pixel colouring, but one single color each.

Solution 2:

It seems to be possible with matplotlib even if it is a bit of a hack:

from mpl_toolkits.mplot3d import axes3d
from mpl_toolkits.mplot3d import art3d
import matplotlib.pyplot as plt
import numpy as np
import matplotlib as mpl

fig = plt.figure()
ax = fig.add_subplot(111, projection='3d')
X, Y, Z = axes3d.get_test_data(0.05)
wire = ax.plot_wireframe(X, Y, Z, rstride=10, cstride=10)

# Retrive data from internal storage of plot_wireframe, then delete it
nx, ny, _  = np.shape(wire._segments3d)
wire_x = np.array(wire._segments3d)[:, :, 0].ravel()
wire_y = np.array(wire._segments3d)[:, :, 1].ravel()
wire_z = np.array(wire._segments3d)[:, :, 2].ravel()
wire.remove()

# create data for a LineCollection
wire_x1 = np.vstack([wire_x, np.roll(wire_x, 1)])
wire_y1 = np.vstack([wire_y, np.roll(wire_y, 1)])
wire_z1 = np.vstack([wire_z, np.roll(wire_z, 1)])
to_delete = np.arange(0, nx*ny, ny)
wire_x1 = np.delete(wire_x1, to_delete, axis=1)
wire_y1 = np.delete(wire_y1, to_delete, axis=1)
wire_z1 = np.delete(wire_z1, to_delete, axis=1)
scalars = np.delete(wire_z, to_delete)

segs = [list(zip(xl, yl, zl)) for xl, yl, zl in \
                 zip(wire_x1.T, wire_y1.T, wire_z1.T)]

# Plots the wireframe by a  a line3DCollection
my_wire = art3d.Line3DCollection(segs, cmap="hsv")
my_wire.set_array(scalars)
ax.add_collection(my_wire)

plt.colorbar(my_wire)
plt.show()

enter image description here

Solution 3:

An official feature request is underway:

The accepted solution doesn't work when X and Y arrays are not the same size.

Solution 4:

It seems the current matplotlib 1.3.1 does not handle such mesh plot or further PDF export. gnuplot.pygnuplot.py 1.8 might be a choice before there is further updates in matplotlib.

Here is an example created via gnuplot: mesh