当X或Y轴的值是字符串时，ax.plot_wireframe错误

Question

我想用matplotlib为我的网站绘制一个曲面三维图，但是我得到了一个错误。以下是源代码：

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

fig = plt.figure()
ax = fig.add_subplot(111, projection='3d')

X = np.array([ '4K', '8K' ])
Y = np.array([ 1, 4 ])
Z = np.array([[0.1925, 0.1848], [0.1807, 0.1966]])

ax.plot_wireframe(X, Y, Z)

plt.show()

我所犯的错误是

Traceback (most recent call last):
  File "wire3d.py", line 21, in <module>
    ax.plot_wireframe(X, Y, Z)
  File "/usr/local/lib/python3.8/dist-packages/matplotlib/_api/deprecation.py", line 415, in wrapper
    return func(*inner_args, **inner_kwargs)
  File "/usr/local/lib/python3.8/dist-packages/mpl_toolkits/mplot3d/axes3d.py", line 1908, in plot_wireframe
    self.auto_scale_xyz(X, Y, Z, had_data)
  File "/usr/local/lib/python3.8/dist-packages/mpl_toolkits/mplot3d/axes3d.py", line 652, in auto_scale_xyz
    self.xy_dataLim.update_from_data_xy(
  File "/usr/local/lib/python3.8/dist-packages/matplotlib/transforms.py", line 967, in update_from_data_xy
    path = Path(xy)
  File "/usr/local/lib/python3.8/dist-packages/matplotlib/path.py", line 129, in __init__
    vertices = _to_unmasked_float_array(vertices)
  File "/usr/local/lib/python3.8/dist-packages/matplotlib/cbook/__init__.py", line 1298, in _to_unmasked_float_array
    return np.asarray(x, float)
ValueError: could not convert string to float: '4K'

有什么问题吗？

Answer 1

您必须指定4K和8K是什么意思：

X = np.array([ 4000, 8000 ])

如果您对在x轴中显示"4K“和"8K”感兴趣，则可以在显示图形之前添加ax.set_xticks(X, [ '4K', '8K' ])。

这是正确的代码：

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

fig = plt.figure()
ax = fig.add_subplot(111, projection='3d')

X = np.array([ 4000, 8000 ])
Y = np.array([ 1, 4 ])
Z = np.array([[0.1925, 0.1848], [0.1807, 0.1966]])

ax.plot_wireframe(X, Y, Z)
ax.set_xticks(X, [ '4K', '8K' ])

plt.show()