计算和显示一个 ConvexHull [英] Calculating and displaying a ConvexHull

问题描述

我正在尝试为python中的一些随机点计算并显示凸包.

这是我当前的代码:

 将numpy导入为np随机导入导入matplotlib.pyplot作为plt导入 cv2积分= np.random.rand(25,2)船体 = ConvexHull(点)plt.plot(points[:,0], points[:,1], 'o',color='c')对于 hull.simplices 中的单纯形:plt.plot(points [simplex，0]，points [simplex，1]，'r')plt.plot(points[hull.vertices,0],points[hull.vertices,1],'r',lw=-1)plt.plot(points[hull.vertices[0],0],points[hull.vertices[0],1],'r-')plt.show()

我的问题:

• 如何在0到9之间更改X，Y标签和点数限制?例如 (0,1,2,3,4,5,6,7,8,9)
• 如何在凸包上用圆标出点?

  PS:要在单独的窗口中显示图，

  来自scipy.spatial的

   导入ConvexHull导入matplotlib.pyplot作为plt将numpy导入为nppoints = np.random.randint(0, 10, size=(15, 2)) # 二维随机点船体= ConvexHull(点)对于(1，2)中的plot_id:图, ax = plt.subplots(ncols=1, figsize=(5, 3))ax.plot(points [:, 0]，points [:, 1]，'.'，color ='k')如果plot_id == 1:ax.set_title('给定积分')别的:ax.set_title('凸包')对于 hull.simplices 中的单纯形:ax.plot(points[simplex, 0], points[simplex, 1], 'c')ax.plot(points [hull.vertices，0]，points [hull.vertices，1]，'o'，mec ='r'，color ='none'，lw = 1，markersize = 10)ax.set_xticks(range(10))ax.set_yticks(range(10))plt.show()

  I'm trying to calculate and show a convex hull for some random points in python.

  This is my current code:

  import numpy as np
  import random
  import matplotlib.pyplot as plt
  import cv2
  
  points = np.random.rand(25,2)   
  
  hull = ConvexHull(points)
  
  plt.plot(points[:,0], points[:,1], 'o',color='c')
  
  for simplex in hull.simplices:
      plt.plot(points[simplex, 0], points[simplex, 1], 'r')
  
  plt.plot(points[hull.vertices,0], points[hull.vertices,1], 'r', lw=-1)
  plt.plot(points[hull.vertices[0],0], points[hull.vertices[0],1], 'r-')
  plt.show()
  

  My questions:

  • How can I change the X,Y labels and points limit between 0 to 9? For example (0,1,2,3,4,5,6,7,8,9)
  • How can I mark the points on the convex hull with a circle? As in example

  解决方案

  Replacing np.rand() with randint(0, 10) will generate the coordinates as integers from 0,1,... to 9.

  Using '.' as marker will result in smaller markers for the given points.

  Using 'o' as marker, setting a markeredgecolor and setting the main color to 'none' will result in a circular marker, which can be used for the points on the hull. The size of the marker can be adapted via markersize=.

  fig, axes = plt.subplots(ncols=..., nrows=...) is a handy way to create multiple subplots.

  Here is some code for a minimal example:

  from scipy.spatial import ConvexHull
  import matplotlib.pyplot as plt
  import numpy as np
  
  points = np.random.randint(0, 10, size=(15, 2))  # Random points in 2-D
  
  hull = ConvexHull(points)
  
  fig, (ax1, ax2) = plt.subplots(ncols=2, figsize=(10, 3))
  
  for ax in (ax1, ax2):
      ax.plot(points[:, 0], points[:, 1], '.', color='k')
      if ax == ax1:
          ax.set_title('Given points')
      else:
          ax.set_title('Convex hull')
          for simplex in hull.simplices:
              ax.plot(points[simplex, 0], points[simplex, 1], 'c')
          ax.plot(points[hull.vertices, 0], points[hull.vertices, 1], 'o', mec='r', color='none', lw=1, markersize=10)
      ax.set_xticks(range(10))
      ax.set_yticks(range(10))
  plt.show()
  

  PS: To show the plots in separate windows:

  from scipy.spatial import ConvexHull
  import matplotlib.pyplot as plt
  import numpy as np
  
  points = np.random.randint(0, 10, size=(15, 2))  # Random points in 2-D
  hull = ConvexHull(points)
  for plot_id in (1, 2):
      fig, ax = plt.subplots(ncols=1, figsize=(5, 3))
      ax.plot(points[:, 0], points[:, 1], '.', color='k')
      if plot_id == 1:
          ax.set_title('Given points')
      else:
          ax.set_title('Convex hull')
          for simplex in hull.simplices:
              ax.plot(points[simplex, 0], points[simplex, 1], 'c')
          ax.plot(points[hull.vertices, 0], points[hull.vertices, 1], 'o', mec='r', color='none', lw=1, markersize=10)
      ax.set_xticks(range(10))
      ax.set_yticks(range(10))
      plt.show()
  

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