我有这个生成椭圆的简单代码
import matplotlib.patches as patches
import matplotlib.pyplot as plt
fig, ax = plt.subplots(subplot_kw={'aspect': 'equal'})
ellipse = patches.Ellipse((0, 0), 4, 2, angle=45, fill=False)
ax.add_artist(ellipse)
ax.set_xlim(-2.2, 2.2)
ax.set_ylim(-2.2, 2.2)
plt.show()
有办法做到这一点吗? 我需要一种通用的方法来使用更复杂的椭圆,谢谢。
我尝试在 patch.Ellipse() 中搜索参数来绘制这些轴线,但没有找到任何东西。
您可以添加椭圆的长轴和短轴。
在我展示的代码中,我制作了主轴,但是您需要处理角度部分(基于椭圆的点),而我只是将其设置为 45 度以发布快速答案。
这样的结果将给出完整的解决方案。
所以,我做了这样的事情:
import matplotlib.patches as patches
import matplotlib.pyplot as plt
import numpy as np
fig, ax = plt.subplots(subplot_kw={'aspect': 'equal'})
#################################
# you need to figure this bit out
#################################
ellipse = patches.Ellipse((0, 0), 4, 2, angle=45, fill=False)
ax.add_artist(ellipse)
ellipse.set_clip_box(ax.bbox)
ellipse.set_alpha(0.1)
ax.annotate("",
xy=(ellipse.center[0], ellipse.center[1] - ellipse.height / 2),
xytext=(ellipse.center[0], ellipse.center[1] + ellipse.height / 2),
arrowprops=dict(arrowstyle="<->", color="black"))
ax.annotate("",
xy=(ellipse.center[0] - ellipse.width / 2, ellipse.center[1]),
xytext=(ellipse.center[0] + ellipse.width / 2, ellipse.center[1]),
arrowprops=dict(arrowstyle="<->", color="black"))
ax.annotate("",
xy=(ellipse.center[0] - ellipse.width / 2 * np.cos(np.deg2rad(ellipse.angle)),
ellipse.center[1] - ellipse.height / 2 * np.sin(np.deg2rad(ellipse.angle))),
xytext=(ellipse.center[0] + ellipse.width / 2 * np.cos(np.deg2rad(ellipse.angle)),
ellipse.center[1] + ellipse.height / 2 * np.sin(np.deg2rad(ellipse.angle))),
arrowprops=dict(arrowstyle="<->", color="black"))
ax.set_xlim(-2.2, 2.2)
ax.set_ylim(-2.2, 2.2)
plt.show()
这会给你留下这样的情节:
总的来说,注释行可以让您完成所需的最后部分。
编辑: 我能够减少到这个:
import matplotlib.patches as patches
import matplotlib.pyplot as plt
fig, ax = plt.subplots(subplot_kw={'aspect': 'equal'})
# patches.Ellipse(center, width, height, angle)
ellipse = patches.Ellipse((0, 0), 4, 2, angle=45, fill=False)
ax.add_artist(ellipse)
ellipse.set_clip_box(ax.bbox)
ax.annotate("",
xy=(ellipse.center[0] - ellipse.width+2 ,
ellipse.center[1] - ellipse.height ),
xytext=(ellipse.center[0] + ellipse.width-1,
ellipse.center[1] + ellipse.height+1),
arrowprops=dict(arrowstyle="<->", color="red"))
ax.set_xlim(-2.2, 2.2;)
ax.set_ylim(-2.2, 2.2)
plt.show()
from math import sin, cos, radians
import matplotlib.patches as patches
import matplotlib.pyplot as plt
fig, ax = plt.subplots(subplot_kw={'aspect': 'equal'})
##############
ellipse_size = (4,2)
ellipse_rotation = 45
ellipse_position = (0,0)
ellipse = patches.Ellipse(ellipse_position, ellipse_size[0], ellipse_size[1], angle=ellipse_rotation, fill=False)
ax.add_artist(ellipse)
ax.set_xlim(-2.2, 2.2)
ax.set_ylim(-2.2, 2.2)
# math for the start and end axis point positions
ax1_points = [
(ellipse_position[0]+ellipse_size[0]/2*cos(radians(ellipse_rotation)),
ellipse_position[1]+ellipse_size[0]/2*sin(radians(ellipse_rotation))),
(ellipse_position[0]+ellipse_size[0]/2*cos(radians(ellipse_rotation + 180)),
ellipse_position[1]+ellipse_size[0]/2*sin(radians(ellipse_rotation + 180)))
]
ax2_points = [
(ellipse_position[0]+ellipse_size[1]/2*cos(radians(ellipse_rotation+90)),
ellipse_position[1]+ellipse_size[1]/2*sin(radians(ellipse_rotation+90))),
(ellipse_position[0]+ellipse_size[1]/2*cos(radians(ellipse_rotation + 270)),
ellipse_position[1]+ellipse_size[1]/2*sin(radians(ellipse_rotation + 270)))]
# ax1 and ax2 contains the start and the end point of the axis ([x,y] format)
# drawing the arrows
arrowprops=dict(arrowstyle="<->", color="red")
ax.annotate("", xy=ax1_points[0], xytext=ax1_points[1], arrowprops=arrowprops)
ax.annotate("", xy=ax2_points[0], xytext=ax2_points[1], arrowprops=arrowprops)
plt.show()
产生这个:
希望这有帮助。