plot_surface matplotlib 中的 facecolors

Question

我想重现这个例子：https://matplotlib.org/3.3.1/gallery/mplot3d/surface3d_3.html#sphx-glr-gallery-mplot3d-surface3d-3-py，但颜色不同。

原代码为：

import matplotlib.pyplot as plt
from matplotlib.ticker import LinearLocator
import numpy as np


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

# Make data.
X = np.arange(-5, 5, 0.25)
xlen = len(X)
Y = np.arange(-5, 5, 0.25)
ylen = len(Y)
X, Y = np.meshgrid(X, Y)
R = np.sqrt(X**2 + Y**2)
Z = np.sin(R)

# Create an empty array of strings with the same shape as the meshgrid, and
# populate it with two colors in a checkerboard pattern.
colortuple = ('y', 'b')
colors = np.empty(X.shape, dtype=str)
for y in range(ylen):
    for x in range(xlen):
        colors[x, y] = colortuple[(x + y) % len(colortuple)]

# Plot the surface with face colors taken from the array we made.
surf = ax.plot_surface(X, Y, Z, facecolors=colors, linewidth=0)

# Customize the z axis.
ax.set_zlim(-1, 1)
ax.zaxis.set_major_locator(LinearLocator(6))

plt.show()

当我将 "colortuple =('y', 'b')" 更改为 "colortuple =('#ff7f0e', '#2ca02c') 时出现此错误：

  File "<ipython-input-41-a355b1dad171>", line 1, in <module>
    runfile('C:/Users/camrane/Downloads/dflt_style_changes-1.py', wdir='C:/Users/camrane/Downloads')

  File "C:\ProgramData\Anaconda3\lib\site-packages\spyder\utils\site\sitecustomize.py", line 705, in runfile
    execfile(filename, namespace)

  File "C:\ProgramData\Anaconda3\lib\site-packages\spyder\utils\site\sitecustomize.py", line 102, in execfile
    exec(compile(f.read(), filename, 'exec'), namespace)

  File "C:/Users/camrane/Downloads/dflt_style_changes-1.py", line 27, in <module>
    surf = ax.plot_surface(X, Y, Z, facecolors=colors, linewidth=0)

  File "C:\ProgramData\Anaconda3\lib\site-packages\mpl_toolkits\mplot3d\axes3d.py", line 1740, in plot_surface
    colset = self._shade_colors(colset, normals)

  File "C:\ProgramData\Anaconda3\lib\site-packages\mpl_toolkits\mplot3d\axes3d.py", line 1790, in _shade_colors
    color = mcolors.to_rgba_array(color)

  File "C:\ProgramData\Anaconda3\lib\site-packages\matplotlib\colors.py", line 267, in to_rgba_array
    result[i] = to_rgba(cc, alpha)

  File "C:\ProgramData\Anaconda3\lib\site-packages\matplotlib\colors.py", line 168, in to_rgba
    rgba = _to_rgba_no_colorcycle(c, alpha)

  File "C:\ProgramData\Anaconda3\lib\site-packages\matplotlib\colors.py", line 212, in _to_rgba_no_colorcycle
    raise ValueError("Invalid RGBA argument: {!r}".format(orig_c))

ValueError: Invalid RGBA argument: '#'

)"

当它是“colortuple =('gray', 'orange') 我有这个错误

  File "<ipython-input-42-a355b1dad171>", line 1, in <module>
    runfile('C:/Users/camrane/Downloads/dflt_style_changes-1.py', wdir='C:/Users/camrane/Downloads')

  File "C:\ProgramData\Anaconda3\lib\site-packages\spyder\utils\site\sitecustomize.py", line 705, in runfile
    execfile(filename, namespace)

  File "C:\ProgramData\Anaconda3\lib\site-packages\spyder\utils\site\sitecustomize.py", line 102, in execfile
    exec(compile(f.read(), filename, 'exec'), namespace)

  File "C:/Users/camrane/Downloads/dflt_style_changes-1.py", line 27, in <module>
    surf = ax.plot_surface(X, Y, Z, facecolors=colors, linewidth=0)

  File "C:\ProgramData\Anaconda3\lib\site-packages\mpl_toolkits\mplot3d\axes3d.py", line 1740, in plot_surface
    colset = self._shade_colors(colset, normals)

  File "C:\ProgramData\Anaconda3\lib\site-packages\mpl_toolkits\mplot3d\axes3d.py", line 1790, in _shade_colors
    color = mcolors.to_rgba_array(color)

  File "C:\ProgramData\Anaconda3\lib\site-packages\matplotlib\colors.py", line 267, in to_rgba_array
    result[i] = to_rgba(cc, alpha)

  File "C:\ProgramData\Anaconda3\lib\site-packages\matplotlib\colors.py", line 168, in to_rgba
    rgba = _to_rgba_no_colorcycle(c, alpha)

  File "C:\ProgramData\Anaconda3\lib\site-packages\matplotlib\colors.py", line 212, in _to_rgba_no_colorcycle
    raise ValueError("Invalid RGBA argument: {!r}".format(orig_c))

ValueError: Invalid RGBA argument: 'o'

就像代码只接受基本颜色一样。

谢谢

Answer 1

有趣的问题。这是由于示例中创建colors 数组的方式所致。

colortuple = ('y', 'b')
colors = np.empty(X.shape, dtype=str)
for y in range(ylen):
    for x in range(xlen):
        colors[x, y] = colortuple[(x + y) % len(colortuple)]

因为colors 数组是用dtype=str 声明的，所以每个单元格只接受1 个字符，并且您尝试使用的颜色会被截断。

从this answer，你可以初始化更大的数组来规避这个问题colors = np.empty(X.shape, dtype='U50')

import matplotlib.pyplot as plt
from matplotlib.ticker import LinearLocator
import numpy as np


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

# Make data.
X = np.arange(-5, 5, 0.25)
xlen = len(X)
Y = np.arange(-5, 5, 0.25)
ylen = len(Y)
X, Y = np.meshgrid(X, Y)
R = np.sqrt(X**2 + Y**2)
Z = np.sin(R)

# Create an empty array of strings with the same shape as the meshgrid, and
# populate it with two colors in a checkerboard pattern.
colortuple = ('xkcd:blue with a hint of purple', '#ff7f0e', 'orange')
colors = np.empty(X.shape, dtype='U50')
for y in range(ylen):
    for x in range(xlen):
        colors[x, y] = colortuple[(x + y) % len(colortuple)]

# Plot the surface with face colors taken from the array we made.
surf = ax.plot_surface(X, Y, Z, facecolors=colors, linewidth=0)

# Customize the z axis.
ax.set_zlim(-1, 1)
ax.zaxis.set_major_locator(LinearLocator(6))

plt.show()