无法使用rotate_around()将matplotlib补丁对象绕特定点旋转 [英] Unable to rotate a matplotlib patch object about a specific point using rotate_around( )

问题描述

我正在尝试使用 rotate_around() 和 rotate_deg_around() 函数围绕特定点旋转 matplotlib 矩形补丁对象.但是，面片始终围绕原点旋转.我不确定如何确保补丁对象围绕特定点旋转.

I am trying to rotate a matplotlib rectangular patch object about a specific point using the rotate_around() and rotate_deg_around() functions. However, the patch is always rotating about the origin. I am not sure how to ensure that the patch object rotates about a specific point.

这里的代码如下:

import numpy as np
import matplotlib.pyplot as plt
import matplotlib.patches as patches
import matplotlib as mpl
fig = plt.figure()
ax = fig.add_subplot(111)
ax.set_xlim(-0.05,1);ax.set_ylim(-0.05,1);
grid('on');

#Rotate rectangle patch object
ts = ax.transData
tr = mpl.transforms.Affine2D().rotate_deg_around(0.2,0.5,10)
t= ts + tr

rec0 = patches.Rectangle((0.2,0.5),0.25,0.2,alpha=0.5)
ax.add_patch(rec0)

#Rotated rectangle patch
rect1 = patches.Rectangle((0.2,0.5),0.25,0.2,color='blue',alpha=0.5,transform=t)
ax.add_patch(rect1);

#The (desired) point of rotation
ax.scatter([0.0,0.2],[0.0,0.5],c=['g','r'],zorder=10)
txt = ax.annotate('Desired point of rotation',xy=(0.2,0.5),fontsize=16,\
xytext=(0.25,0.35),arrowprops=dict(arrowstyle="->",connectionstyle="arc3,rad=-.2"))
txt2 = ax.annotate('Actual point of rotation',xy=(0.0,0.0),fontsize=16,\
xytext=(0.15,0.15),arrowprops=dict(arrowstyle="->",connectionstyle="arc3,rad=.2"))

plt.show()

这是上面代码的输出:

我也尝试过翻译，rotate_about_origin和translate_back.但是，转换转换也不起作用.任何简单翻译的帮助/示例也将非常有用.

I have also tried to do translate, rotate_about_origin, and translate_back. However, the translate transform was not working either. Any help/example of simple translation would also be very useful.

谢谢.

推荐答案

您旋转的坐标不是数据坐标.你必须先转换它们，即

The coordinates you rotate around are not the data coordinates. You have to transform them first, i.e.

import numpy as np
import matplotlib.pyplot as plt
import matplotlib.patches as patches
import matplotlib as mpl
fig = plt.figure()
ax = fig.add_subplot(111)
ax.set_xlim(-0.05,1);ax.set_ylim(-0.05,1);
plt.grid('on');

#Rotate rectangle patch object
ts = ax.transData
coords = ts.transform([0.2, 0.5])
tr = mpl.transforms.Affine2D().rotate_deg_around(coords[0], coords[1], 10)
t= ts + tr

rec0 = patches.Rectangle((0.2,0.5),0.25,0.2,alpha=0.5)
ax.add_patch(rec0)

#Rotated rectangle patch
rect1 = patches.Rectangle((0.2,0.5),0.25,0.2,color='blue',alpha=0.5,transform=t)
ax.add_patch(rect1);

#The (desired) point of rotation
ax.scatter([0.0,0.2],[0.0,0.5],c=['g','r'],zorder=10)
txt = ax.annotate('Desired point of rotation',xy=(0.2,0.5),fontsize=16,\
xytext=(0.25,0.35),arrowprops=dict(arrowstyle="->",connectionstyle="arc3,rad=-.2"))
txt2 = ax.annotate('Actual point of rotation',xy=(0.0,0.0),fontsize=16,\
xytext=(0.15,0.15),arrowprops=dict(arrowstyle="->",connectionstyle="arc3,rad=.2"))

plt.show()

显然，该代码仅适用于交互式显示，而当调整窗口大小或保存图形时无效.比较这两个图像:

Apparently, the code only works for the interactive display, but not when the window is resized or the figure is saved. Compare these two images:

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