多边形顶点排序

http://www.developerq.com/article/1489144164

# -*- coding:utf-8 -*-
import sys

import math
import matplotlib.patches as patches
import pylab

def polygon_sort(pp):

    # compute centroid
    cent=(sum([p[0] for p in pp])/len(pp),sum([p[1] for p in pp])/len(pp))
    # sort by polar angle
    pp.sort(key=lambda p: math.atan2(p[1]-cent[1],p[0]-cent[0]))
    # plot points
    pylab.scatter([p[0] for p in pp],[p[1] for p in pp])
    # plot polyline
    pylab.gca().add_patch(patches.Polygon(pp,closed=False,fill=False))
    pylab.grid()
    pylab.show()

pp=[(-0.500000050000005, -0.5), (-0.499999950000005, 0.5), (-0.500000100000005, -1.0), (-0.49999990000000505, 1.0), (0.500000050000005, -0.5)]

polygon_sort(pp)

c++版的多边形排序：

【计算几何】多边形点集排序 - 一点心青 - 博客园

后面有评论，好像有问题