python - 使用 matplotlib 围绕点旋转矩形

Question

我想用matplotlib旋转Rectangles，但是正常的patch总是围绕Rectangle的左下角旋转。有没有办法描述更一般的转换？例如，我想围绕矩形较短边的中点旋转，以便结果看起来像时钟指针的运动。

import numpy as np
import matplotlib.pyplot as plt
from matplotlib.patches import Rectangle

height = 0.1
width = 1
fig, ax = plt.subplots()
ax.set_aspect('equal')
ax.set_xlim([-width * 1.2, width * 1.2])
ax.set_ylim([-width * 1.2, width * 1.2])

ax.plot(0, 0,  color='r', marker='o', markersize=10)
for deg in range(0, 360, 45):
    rec = Rectangle((0, 0), width=width, height=height, 
                    angle=deg, color=str(deg / 360), alpha=0.9)
    ax.add_patch(rec)

Answer 1

与其他答案相同，只是没有子类化和使用私有(private)属性。

import numpy as np
import matplotlib.pyplot as plt
from matplotlib.transforms import Affine2D

height = 0.1
width = 1
fig, ax = plt.subplots()
ax.set_aspect('equal')
ax.set_xlim([-width * 1.2, width * 1.2])
ax.set_ylim([-width * 1.2, width * 1.2])
ax.plot(0, 0,  color='r', marker='o', markersize=10)
point_of_rotation = np.array([0, height/2])          # A
# point_of_rotation = np.array([width/2, height/2])  # B
# point_of_rotation = np.array([width/3, height/2])  # C
# point_of_rotation = np.array([width/3, 2*height])  # D

for deg in range(0, 360, 45):
    rec = plt.Rectangle(-point_of_rotation, width=width, height=height, 
                        color=str(deg / 360), alpha=0.9,
                        transform=Affine2D().rotate_deg_around(*(0,0), deg)+ax.transData)
    ax.add_patch(rec)
plt.show()