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[Bug]: error plotting z-axis array with np.nan -- does not plot with cmap option (surface plot) #20905

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sbeer3 opened this issue Aug 25, 2021 · 5 comments
Closed

[Bug]: error plotting z-axis array with np.nan -- does not plot with cmap option (surface plot) #20905

sbeer3 opened this issue Aug 25, 2021 · 5 comments
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topic: mplot3d
Milestone
v3.5.0

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@sbeer3
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sbeer3 commented Aug 25, 2021

Bug summary

The bug I have is that when trying to plot a surface plot, and have some z axis values as np.nan, if the cmap option is included in the construction of the surface plot, the plot shows up as an empty space.
image

Code for reproduction

xx = np.linspace(0.0, 100, 101) 
yy = np.linspace(0.0, 100, 101) 
zz = np.linspace(0.0, 0, 1)
x,y,z = np.meshgrid(xx,yy,zz,indexing='ij')

z[30][30] = np.nan

fig = plt.figure(figsize=(13,13))           
ax = fig.add_subplot(111,projection='3d')
ax.plot_surface(x[:,:,0],y[:,:,0],z[:,:,0], rstride=1, cstride=1, cmap='coolwarm', edgecolor='none') 
#the cmap option causes a blank plot

Actual outcome

image

Expected outcome

The plot should just be a flat surface plot 100 x 100 with a np.nan value at (30,30)

Operating system

Windows 10 / Ubuntu

Matplotlib Version

3.4.2

Matplotlib Backend

No response

Python version

3.8.10

Jupyter version

No response

Other libraries

No response

Installation

pip

Conda channel

No response
@tacaswell
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This appears to fixed on the default branch and v3.5.x

so

import matplotlib
import matplotlib.pyplot as plt
import numpy as np

xx = np.linspace(0.0, 100, 101)
yy = np.linspace(0.0, 100, 101)
zz = np.linspace(0.0, 0, 1)
x, y, z = np.meshgrid(xx, yy, zz, indexing="ij")

z[30][30] = np.nan

fig = plt.figure(figsize=(13, 13))
ax = fig.add_subplot(111, projection="3d")
ax.plot_surface(
    x[:, :, 0],
    y[:, :, 0],
    z[:, :, 0],
    rstride=1,
    cstride=1,
    cmap="coolwarm",
    edgecolor="none",
)
ax.set_title(f"Matplotlib: {matplotlib.__version__}")
# the cmap option causes a blank plot
plt.show()

You can test out the 3.5 beta release now if you want:

pip install matplotlib --upgrade --pre

@tacaswell tacaswell added this to the v3.5.0 milestone Aug 25, 2021
@tacaswell
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I am going to close this as fixed.

I do not think we are going to have another 3.4.x release so even if we tracked down the fix for this and backported it (assuming it is a small enough change to backport), we would likely not release it. That said, if someone did the work to track this down we could consider it.

@sbeer3
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sbeer3 commented Aug 25, 2021

@tacaswell appreciate it

@WeatherGod
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WeatherGod commented Aug 25, 2021 via email

@tacaswell
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Ah, then that is definitely not a back-port candidate!

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@tacaswell @WeatherGod @sbeer3