刺

这个演示比较：

• 正常的斧头，四面都有刺；

• 仅在左侧和底部带有刺的轴；

• 使用自定义边界来限制脊椎范围的轴。

每个axes.Axes都有一个Spine对象列表，可通过容器访问ax.spines。

import numpy as np
import matplotlib.pyplot as plt


x = np.linspace(0, 2 * np.pi, 100)
y = 2 * np.sin(x)

# Constrained layout makes sure the labels don't overlap the axes.
fig, (ax0, ax1, ax2) = plt.subplots(nrows=3, constrained_layout=True)

ax0.plot(x, y)
ax0.set_title('normal spines')

ax1.plot(x, y)
ax1.set_title('bottom-left spines')

# Hide the right and top spines
ax1.spines.right.set_visible(False)
ax1.spines.top.set_visible(False)
# Only show ticks on the left and bottom spines
ax1.yaxis.set_ticks_position('left')
ax1.xaxis.set_ticks_position('bottom')

ax2.plot(x, y)

# Only draw spine between the y-ticks
ax2.spines.left.set_bounds(-1, 1)
# Hide the right and top spines
ax2.spines.right.set_visible(False)
ax2.spines.top.set_visible(False)
# Only show ticks on the left and bottom spines
ax2.yaxis.set_ticks_position('left')
ax2.xaxis.set_ticks_position('bottom')

plt.show()

# .. admonition:: References
#
#    The use of the following functions, methods, classes and modules is shown
#    in this example:
#
#    - `matplotlib.Spines.set_visible`
#    - `matplotlib.Spines.set_bounds`
#    - `matplotlib.axis.set_ticks_position`