Python: Is there a way to plot a "partial" surface plot with Matplotlib?

Question

I wanted to plot a "partial" surface plot like the following one with Matplotlib

Note that it's not a complete meshgrid on X-Y plane but missing a corner from top view. The following is the code I tried but didn't work.

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

X = np.array([[0,1],
              [0,1,2],
              [0,1,2,3],
             ])
Y = np.array([[0,0],
              [1,1,1],
              [2,2,2,2],
             ])
Z = np.array([[0.5, 0.6],
              [0.7, 0.8, 0.9],
              [1.0, 1.1, 1.2, 1.3],
             ])
fig = pyplot.figure()
ax = fig.add_subplot(111, projection='3d')
ax.plot_surface(X,Y,Z)

The error being:

ValueError: setting an array element with a sequence.

Any pointer would be appreciated! Thanks!

Answer 1

You can do this easily by using np.nan values for Z in the regions you don't want to plot. Here's a modified version of this example but with the cut, as show below:

from mpl_toolkits.mplot3d import Axes3D
from matplotlib import cm
from matplotlib.ticker import LinearLocator, FormatStrFormatter
import matplotlib.pyplot as plt
import numpy as np

fig = plt.figure()
ax = fig.gca(projection='3d')
X = np.arange(-5, 5, 0.25)
Y = np.arange(-5, 5, 0.25)
X, Y = np.meshgrid(X, Y)
R = np.sqrt(X**2 + Y**2)
Z = np.sin(.5*R)

Z[X+Y>4.] = np.nan  # the diagonal slice

surf = ax.plot_surface(X, Y, Z, rstride=1, cstride=1, cmap=cm.coolwarm,
                       linewidth=0, antialiased=False, vmin=-1, vmax=1)
ax.set_zlim(-1.01, 1.01)

ax.zaxis.set_major_locator(LinearLocator(10))
ax.zaxis.set_major_formatter(FormatStrFormatter('%.02f'))

fig.colorbar(surf, shrink=0.5, aspect=5)

plt.show()

Note here also that I had to use vmin and vmax keywords in the plot command or the color scaling would be thrown by the nans.