python - 有没有一种方法可以绘制一侧带有圆弧的 matplotlib 补丁矩形？

Question

我需要画一个有 4 条边的多边形，右边是圆弧。类似这样:

我曾尝试使用 matplotlib 提供的代码来绘制贝塞尔曲线，但没有成功。任何帮助将不胜感激:)

from matplotlib.path import Path
import matplotlib.patches as patches


verts = [
   (0., 0.),   # P0
   (0, 1.),  # P1
   (1., 1),  # P2
   (1, 0.),  # P3
]

codes = [
    Path.MOVETO,
    Path.CURVE4,
    Path.CURVE4,
    Path.CURVE4,
]

path = Path(verts, codes)

fig, ax = plt.subplots()
patch = patches.PathPatch(path, facecolor='none', lw=2)
ax.add_patch(patch)

xs, ys = zip(*verts)
ax.plot(xs, ys, lw=2, color='black', ms=10)
ax.set_xlim(-0.1, 1.1)
ax.set_ylim(-0.1, 1.1)
plt.show()

Answer 1

我不知道这是否是绘制路径对象的正确方法 - 您最好等待对这种方法有经验的人。但在那之前，您可以这样做:

from matplotlib.path import Path
import matplotlib.patches as patches


verts = [
   (0, 0),    # P0
   (0, 1),    # P1
   (1, 1),    # P2
   (0.4, 1),  #these are the vertices for the 
   (0.2, 0),  #Bezier curve
   (0.5, 0),  # P3
   (0, 0)     #and back to P0
]

codes = [
    Path.MOVETO,  # P0
    Path.LINETO,  #line to P1
    Path.LINETO,  #line to P2
    Path.CURVE4,  #control point one for the Bezier curve
    Path.CURVE4,  #control point two
    Path.CURVE4,  #end point for the Bezier curve
    Path.LINETO   #and back to P0
 ]

path = Path(verts, codes)

fig, ax = plt.subplots()
patch = patches.PathPatch(path, facecolor='none', lw=2)
ax.add_patch(patch)

#you can add the hull figure for the Bezier curve
#xs, ys = zip(*verts)
#ax.plot(xs, ys, "x--", lw=2, color='black', ms=10) 

ax.set_xlim(-0.1, 1.1)
ax.set_ylim(-0.1, 1.1)
plt.show()

示例输出:

matplotlib documentation说对于贝塞尔曲线，你需要(除了你当前的位置)两个控制点和一个终点。因此，您的四点方法可能还不够。