PostGIS地图路径算法优化,解决MultiLineString类型计算错误

使用前面博客计算路径的时候，有时候会产生MultiLineString不支持计算的问题，针对这个问题进行了优化。

-- FUNCTION: public.pgr_road_compute(double precision, double precision, double precision, double precision)

-- DROP FUNCTION public.pgr_road_compute(double precision, double precision, double precision, double precision);

CREATE OR REPLACE FUNCTION public.pgr_road_compute(
	startx double precision,
	starty double precision,
	endx double precision,
	endy double precision)
    RETURNS geometry
    LANGUAGE 'plpgsql'

    COST 100
    VOLATILE STRICT 
AS $BODY$
    
  
    
  
declare   
    
  
    v_startLine geometry;--离起点最近的线   
  
    v_endLine geometry;--离终点最近的线   
  
       
  
    v_startTarget integer;--距离起点最近线的终点  
  
    v_startSource integer;  
  
    v_endSource integer;--距离终点最近线的起点  
  
    v_endTarget integer;  
  
   
  
    v_statpoint geometry;--在v_startLine上距离起点最近的点   
  
    v_endpoint geometry;--在v_endLine上距离终点最近的点   
  
       
  
    v_res geometry;--最短路径分析结果  
  
    v_res_a geometry;  
  
    v_res_b geometry;  
  
    v_res_c geometry;  
  
    v_res_d geometry;
	
	v_start_temp geometry;
	v_start_temp1 geometry;
	v_start_temp2 geometry;
	v_end_temp geometry;
	v_end_temp1 geometry;
	v_end_temp2 geometry;
  
   
  
    v_perStart float;--v_statpoint在v_res上的百分比   
  
    v_perEnd float;--v_endpoint在v_res上的百分比   
  
   
  
    v_shPath_se geometry;--开始到结束  
  
    v_shPath_es geometry;--结束到开始  
  
    v_shPath geometry;--最终结果  
  
    tempnode float;    
      
    startpoint geometry;  
    endpoint geometry;  
  
    v_shPath1 geometry;--一次结果  
    v_shPath2 geometry;--二次结果  
    star_line geometry; --起点到最近点的线  
    end_line geometry; --终点到最近点的线  
    geoARR geometry[];  
  
begin  
  

    --查询离起点最近的线   
    --4326坐标系  
    --找起点15米范围内的最近线  
  
    execute 'select geom, source, target  from  roadline'  
  
                            ' where ST_DWithin(geom,ST_Geometryfromtext(''point('||         startx ||' ' || starty||')'',4326),3000)  
  
                             order by ST_Distance(geom,ST_GeometryFromText(''point('|| startx ||' '|| starty ||')'',4326))  limit 1'  
  
                            into v_startLine, v_startSource ,v_startTarget;   
  
raise notice '%',  v_startSource;  
raise notice '%', v_startTarget;  
  
    --查询离终点最近的线   
    --找终点15米范围内的最近线  
  
    execute 'select geom, source, target from roadline'  
  
                            ' where ST_DWithin(geom,ST_Geometryfromtext(''point('|| endx || ' ' || endy ||')'',4326),3000)     
  
                            order by ST_Distance(geom,ST_GeometryFromText(''point('|| endx ||' ' || endy ||')'',4326))  limit 1'  
  
                            into v_endLine, v_endSource,v_endTarget;   
raise notice '%',  v_endSource;  
raise notice '%', v_endTarget;  
   
  
    --如果没找到最近的线，就返回null   
  
    if (v_startLine is null) or (v_endLine is null) then   
  
        return null;   
  
    end if ;   
  
   
  
    select  ST_ClosestPoint(v_startLine, ST_Geometryfromtext('point('|| startx ||' ' || starty ||')',4326)) into v_statpoint;   
  
    select  ST_ClosestPoint(v_endLine, ST_GeometryFromText('point('|| endx ||' ' || endy ||')',4326)) into v_endpoint;   
  
     
  
   -- ST_Distance   
  
       
  
    --从开始的起点到结束的起点最短路径  
  
    execute 'SELECT st_linemerge(st_union(b.geom)) ' ||  
  
    'FROM pgr_kdijkstraPath(   
  
    ''SELECT gid as id, source, target, length as cost FROM roadline '','   
  
    ||v_startSource || ', ' ||'array['||v_endSource||'] , false, false   
  
    ) a, roadline b   
  
    WHERE a.id3=b.gid     
  
    GROUP by id1     
  
    ORDER by id1' into v_res ;  
  
     
  
    --从开始的终点到结束的起点最短路径  
  
    execute 'SELECT st_linemerge(st_union(b.geom)) ' ||  
  
    'FROM pgr_kdijkstraPath(   
  
    ''SELECT gid as id, source, target, length as cost FROM roadline'','   
  
    ||v_startTarget || ', ' ||'array['||v_endSource||'] , false, false   
  
    ) a, roadline b   
  
    WHERE a.id3=b.gid     
  
    GROUP by id1     
  
    ORDER by id1' into v_res_b ;  
  
   
  
    --从开始的起点到结束的终点最短路径  
  
    execute 'SELECT st_linemerge(st_union(b.geom)) ' ||  
  
    'FROM pgr_kdijkstraPath(   
  
    ''SELECT gid as id, source, target, length as cost FROM roadline'','   
  
    ||v_startSource || ', ' ||'array['||v_endTarget||'] , false, false   
  
    ) a, roadline b   
  
    WHERE a.id3=b.gid     
  
    GROUP by id1     
  
    ORDER by id1' into v_res_c ;  
  
   
  
    --从开始的终点到结束的终点最短路径  
  
    execute 'SELECT st_linemerge(st_union(b.geom)) ' ||  
  
    'FROM pgr_kdijkstraPath(   
  
    ''SELECT gid as id, source, target, length as cost FROM roadline'','   
  
    ||v_startTarget || ', ' ||'array['||v_endTarget||'] , false, false   
  
    ) a, roadline b   
  
    WHERE a.id3=b.gid     
  
    GROUP by id1     
  
    ORDER by id1' into v_res_d ;  
  
   
  
    if(ST_Length(v_res) > ST_Length(v_res_b)) then  
  
       v_res = v_res_b;  
  
    end if;  
  
     
  
    if(ST_Length(v_res) > ST_Length(v_res_c)) then  
  
       v_res = v_res_c;  
  
    end if;  
  
     
  
    if(ST_Length(v_res) > ST_Length(v_res_d)) then  
  
       v_res = v_res_d;  
  
    end if;  
  
               
  
   
  
    --如果找不到最短路径，就返回null   
  
    if(v_res is null) then   
  
        return null;   
  
    end if;   
  
       
  
    --将v_res,v_startLine,v_endLine进行拼接   
  
    --select  st_linemerge(ST_Union(array[v_startLine,v_res,v_endLine])) into v_res;  
  
     select  ST_LineLocatePoint(v_startLine, v_statpoint) into v_perStart; 
     select  ST_LineLocatePoint(v_endLine, v_endpoint) into v_perEnd;
	 
	 SELECT ST_Line_SubString(v_startLine,v_perStart, 1) into v_start_temp1;
	 SELECT ST_Line_SubString(v_startLine,0,v_perStart) into v_start_temp2;
	 
	 SELECT ST_Line_SubString(v_endLine,v_perEnd, 1) into v_end_temp1;
	 SELECT ST_Line_SubString(v_endLine,0,v_perEnd) into v_end_temp2;
	 
	 raise notice '%',  v_perStart;  
     raise notice '%', v_perEnd;
	 
	 raise notice '%', ST_Distance(v_res,v_start_temp1);
	 raise notice '%', ST_Distance(v_res,v_start_temp2);
	 raise notice '%', ST_Distance(v_res,v_end_temp2);
	 raise notice '%', ST_Distance(v_res,v_end_temp1);
	 
	 v_start_temp=v_start_temp1;
	 if(ST_Distance(v_res,v_start_temp1) > ST_Distance(v_res,v_start_temp2)) then   
      v_start_temp=v_start_temp2; 
    end if;  
	 v_end_temp=v_end_temp1;
	 if(ST_Distance(v_res,v_end_temp1) > ST_Distance(v_res,v_end_temp2)) then   
      v_end_temp=v_end_temp2; 
    end if;  
    --return ST_AsGeoJSON(v_res); 
	--return v_res;
	
  
   -- select  ST_LineLocatePoint(v_res, v_statpoint) into v_perStart;   
  
   -- select  ST_LineLocatePoint(v_res, v_endpoint) into v_perEnd;   
  
          
  
    --if(v_perStart > v_perEnd) then   
  
    --    tempnode =  v_perStart;  
  
    --   v_perStart = v_perEnd;  
  
    --    v_perEnd = tempnode;  
  
    --end if;  
  
          
  
    --截取v_res   
    --拼接线  
  
    --SELECT ST_Line_SubString(v_res,v_perStart, v_perEnd) into v_shPath1; 
	select  st_linemerge(ST_Union(array[v_start_temp,v_res,v_end_temp])) into v_shPath1;
	
  
 --接下来进行  
 --找线的端点  
 select ST_SetSRID( ST_MakePoint(startx , starty),4326 )into startpoint;  
 select ST_SetSRID( ST_MakePoint(endx , endy),4326 )into endpoint;  
 select ST_MakeLine( v_statpoint,startpoint) into star_line;   
 select ST_MakeLine( v_endpoint,endpoint) into end_line;    

geoARR :=array[end_line,v_shPath1,star_line];  
select st_union(geoARR) into v_shPath;  
   
   raise notice '%', '返回数据';  
   
    return v_shPath; 
	--return ST_AsGeoJSON(v_shPath);
  
   
  
end;   
  

$BODY$;

ALTER FUNCTION public.pgr_road_compute(double precision, double precision, double precision, double precision)
    OWNER TO postgres;

转载自：https://blog.csdn.net/GISuuser/article/details/80504754