剔除自相交线上的环

import numpy as np
from functools import partial
from shapely.geometry import Point, LineString
from shapely.ops import substring, split, linemerge
   

class removeRingOnLineSting():
    # 去除自相交线上的小环
    # 基本思路 1 定位自相交点 2 自相交点分割线 3 分割线合并 根据长度筛选最长的两个
    # todo1 如环上环
    def __init__(self, ls, torelance=1):
        self.ls = ls
        self.torelance = torelance
    
    def crossPoint(self):
        # 定位自相交点
        N =  int(self.ls.length) // self.torelance
        sp = np.linspace(0, 1, N)[1:-1]
        pfun = partial(substring, geom=self.ls, normalized=1)
        cp = set()
        for p in sp:
            t1 = pfun(start_dist=0, end_dist=p)
            tp = pfun(start_dist=p, end_dist=p)
            t2 = pfun(start_dist=p, end_dist=1)
            
            if not t1.touches(t2):
                mp = [_ for _ in t1.intersection(t2).geoms if _ != tp]
                cp.update(mp)
        return cp
    
    def removeRing(self):
        sp = self.crossPoint()
        for p in sp:
            mls = split(self.ls, p.buffer(self.torelance/2))
            mls = [_ for _ in mls.geoms]
            mls = sorted(mls, key=lambda x: x.length)
            line1, line2 = mls[-2:]
            self.ls = self.mergeLineWithGap(line1, line2)
        return self.ls
        

    @staticmethod
    def mergeLineWithGap(line1, line2, torelance=3):
        ps1, pe1 = Point(line1.coords[0]), Point(line1.coords[-1])
        ps2, pe2 = Point(line2.coords[0]), Point(line2.coords[-1])
        
        if ps1.distance(pe2) > pe1.distance(ps2):
            gap_line = LineString([pe1, ps2])
            return linemerge([line1, gap_line, line2])
        else:
            gap_line = LineString([pe2, ps1])
            return linemerge([line2, gap_line, line1])
    

if __name__ == "__main__":
    
    pnts = [(-7,0), (1,0), (1,1), (0,1), (0,-2), (-1,-2),(-1,-1),(7,-1)]
    ls = LineString(pnts)
    
    algo = removeRingOnLineSting(ls)
    rls = algo.removeRing()