matplotlib pcolor not working when used as “2D plot in 3D”

Question

I am trying to add a pcolor plot to the example code given here http://matplotlib.org/examples/mplot3d/2dcollections3d_demo.html

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

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

x = np.linspace(0, 1, 100)
y = np.sin(x * 2 * np.pi) / 2 + 0.5
ax.plot(x, y, zs=0, zdir='z', label='zs=0, zdir=z')

colors = ('r', 'g', 'b', 'k')
for c in colors:
    x = np.random.sample(20)
    y = np.random.sample(20)
    ax.scatter(x, y, 0, zdir='y', c=c)

xc = np.linspace(0, 1, 100)
yc = np.linspace(0, 1, 100)
fc = np.random.random((len(xc),len(yc)))
ax.pcolor(xc,yc,fc, zdir = 'x')

ax.legend()
ax.set_xlim3d(0, 1)
ax.set_ylim3d(0, 1)
ax.set_zlim3d(0, 1)

plt.show()

Just few new lines when compared to the original script. Unfortunately, it doesn't end well and I really don't understand why.

Traceback (most recent call last):
  File "/opt/local/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/site-packages/matplotlib/artist.py", line 61, in draw_wrapper
    draw(artist, renderer, *args, **kwargs)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/site-packages/matplotlib/figure.py", line 1159, in draw
    func(*args)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/site-packages/mpl_toolkits/mplot3d/axes3d.py", line 271, in draw
    for col in self.collections]
  File "/opt/local/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/site-packages/mpl_toolkits/mplot3d/axes3d.py", line 271, in <listcomp>
    for col in self.collections]
AttributeError: 'PolyCollection' object has no attribute 'do_3d_projection'

Thank you all for the support.

Answer 1

It is not clear what you want to achieve. There is a 3D plot in the example but pcolor is a 2D plot. You can't add a pcolor plot to the 3D plot, that's why you get the error, so add a new figure:

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

x = np.linspace(0, 1, 100)
y = np.sin(x * 2 * np.pi) / 2 + 0.5
ax.plot(x, y, zs=0, zdir='z', label='zs=0, zdir=z')

colors = ('r', 'g', 'b', 'k')
for c in colors:
    x = np.random.sample(20)
    y = np.random.sample(20)
    ax.scatter(x, y, 0, zdir='y', c=c)

ax.legend()
ax.set_xlim3d(0, 1)
ax.set_ylim3d(0, 1)
ax.set_zlim3d(0, 1)


fig = plt.figure()
xc = np.linspace(0, 1, 100)
yc = np.linspace(0, 1, 100)
fc = np.random.random((len(xc),len(yc)))
plt.pcolor(xc,yc,fc,cmap='RdBu')
plt.colorbar() 

pcolor has no attribute zdir , so you need to adjust the order of xc,yc,fc in the right way, depending on what you actually want to see.