pgrouting 管线 联通分析

背景描述

啦啦啦啦，然后拉拉阿里，然后啦啦啦，最后就写了这个记录一下

数据准备

1 管线数据

数据要求（拓扑检查）

1. 数据没有重叠要求

2. 数据悬挂点问题得到合理结局，不存在数据连接点不一样的线

3. 数据能按照正常方向处理（如果没有流向等方向，数据将按照要素的绘制方向进行）

4. 数据能够有通和不通的标识

导入到postgis中

id	geom	shape_leng
0	0105000020110F000001000000010200000002000000CE19510898216741808CB98B6D004F412C431C4D9821674190D409202E004F41	126.8595169
1	0105000020110F000001000000010200000002000000CE19510898216741808CB98B6D004F41B8D1001CBA21674130CB103769004F41	272.7527582
2	0105000020110F0000010000000102000000020000006C9A77AA9721674120C9E50FC4004F41CE19510898216741808CB98B6D004F41	173.0574528
3	0105000020110F0000010000000102000000020000006C9A77AA9721674120C9E50FC4004F41E61DA7BA66216741E07A149EC5004F41	391.506559
4	0105000020110F000001000000010200000003000000EC9E3C8E97216741B0D85F6EED004F414E62108297216741801D384FE9004F416C9A77AA9721674120C9E50FC4004F41	82.75757135
5	0105000020110F000001000000010200000002000000EC9E3C8E97216741B0D85F6EED004F41744694CEAE21674160FE431AEA004F41	186.1297867
6	0105000020110F000001000000010200000006000000143FC652A1216741701283205B014F412A189550A2216741701283784A014F41C0CAA1F19E216741A0BDC1C73D014F412C431C4D98216741D0D556FC25014F41C66D34CE97216741F05A421603014F41EC9E3C8E97216741B0D85F6EED004F41	255.8795071
7	0105000020110F000001000000010200000002000000143FC652A1216741701283205B014F4182734670B5216741E0F21F825C014F41	160.9456115
8	0105000020110F00000100000001020000000200000082734670B5216741E0F21F825C014F41B0506BE2BB216741907571F35C014F41	51.57459883
9	0105000020110F000001000000010200000002000000B0506BE2BB216741907571F35C014F41FC87F465BB21674120C05BB0EB004F41	226.5574896
10	0105000020110F000001000000010200000002000000C286A717DF216741F097DD3B5D014F41182653A5D8216741C06D34E88C004F41	419.8332718
11	0105000020110F000001000000010200000003000000C286A717DF216741F097DD3B5D014F414E401313F8216741705F07865B014F41A089B0CB0C226741903177555A014F41	365.6724458
12	0105000020110F000001000000010200000002000000B0506BE2BB216741907571F35C014F41EE7C3FF1C12167419028ED5D5D014F41	48.47053948
13	0105000020110F000001000000010200000003000000EE7C3FF1C12167419028ED5D5D014F41F0164886CF216741F095B24C5E014F41C286A717DF216741F097DD3B5D014F41	233.2344497
14	0105000020110F000001000000010200000002000000F4FDD4AE982167412063EE827E014F41143FC652A1216741701283205B014F41	98.92549714
15	0105000020110F000001000000010200000003000000F085C9D09821674120FDF60DAA014F418295434977216741B08BDB18A4014F41083D9BC561216741B08BDB18A4014F41	440.6138972
16	0105000020110F000001000000010200000002000000F4FDD4AE982167412063EE827E014F41F085C9D09821674120FDF60DAA014F41	87.09266423
17	0105000020110F00000100000001020000000300000082734670B5216741E0F21F825C014F41168C4A8AB6216741D0C342CD80014F41D8F0F426B52167418026C27EBB014F41	191.0307803
18	0105000020110F000001000000010200000003000000EE7C3FF1C12167419028ED5D5D014F415817B7D7C1216741305530A2C2014F41623255BEC1216741E0D7812BE1014F41	263.6128224
19	0105000020110F000001000000010200000002000000F085C9D09821674120FDF60DAA014F41D881730899216741A0DFBE6EF1014F41	142.7666976
20	0105000020110F000001000000010200000002000000D881730899216741A0DFBE6EF1014F410022FDD4E5216741A0DFBE76ED014F41	614.4430713
21	0105000020110F0000010000000102000000020000003AB4C8489921674170787AED43024F4152962116602167412051DACB3A024F41	457.9471985
22	0105000020110F000001000000010200000002000000D881730899216741A0DFBE6EF1014F413AB4C8489921674170787AED43024F41	165.0023479
23	0105000020110F0000010000000102000000040000003AB4C8489921674170787AED43024F413A014D649921674120E4833667024F4102098A3199216741A0B437707B024F41141DC96199216741803F35BE9E024F41	181.6831255
24	0105000020110F000001000000010200000002000000141DC96199216741803F35BE9E024F41F6065F9ADD216741E08C28F59B024F41	545.7967295
25	0105000020110F000001000000010200000002000000141DC96199216741803F35BE9E024F41CAE53F829921674140795880B6024F41	47.52752875
26	0105000020110F000001000000010200000003000000CAE53F829921674140795880B6024F41907EFB5C6E21674190C2F518BA024F41ECC0396D5B216741F0263110BE024F41	496.9394137
27	0105000020110F000001000000010200000002000000CAE53F829921674140795880B6024F4152DA1B629A216741505986505A034F41	327.7010778

分析

建立管线拓扑关系

建立拓扑关系主要目的是为了确定管线每一段的源头和终点，简单说就是两个阀之间关系。数据库中入库数据确定管线的上游阀source和下游阀target，cost用于计算连通，cost>0表示上游到下游可联通，cost<0表示不通
reverse_cost也是用于标识连通性，reverse_cost>0标识下游到上游是联通的,reverse_cost<0标识不通

 ALTER TABLE testpipeline ADD COLUMN "source" INTEGER  default null;
 ALTER TABLE testpipeline ADD COLUMN "target" INTEGER  default null;
 ALTER TABLE testpipeline ADD COLUMN "cost" DOUBLE PRECISION  default null;

注意：如果数据量大，可以通过创建索引提高查询效率，分别穿件source和target的索引

赋值

这里使用管线长度来做为联通性标识，即从source到target都是联通的

UPDATE testpipeline SET cost =st_length(geom);

如果是供水等管线，可以更具实际情况对source、target、cost,reverse_cost赋值

拓扑创建

创建拓扑是给线生成点文件
原理是提取线段的起点和结束点，作为管线(testpipeline)的source和target。按照折线的绘制方向生成。
生成一个新的点表，存储有id,和空间信息

select pgr_createtopology('testpipeline',0.0001,the_geom:='geom',id:='id',source:='source',target:='target',rows_where:='true', clean:=false)

• edge_table：text，表名’testpipeline’
• tolerance：float8，误差缓冲值，两个点的距离在这个距离内，就算重合为一点。0.0001
• the_geom：text，该表的空间坐标字段’geom’
• id：text，该表的主键 ‘id’
• source：text，空间起点编号’source’
• target：text，空间终点编号’target’
• rows_where：text，条件选择子集或行。默认值为true，表示源或目标具有空值的所有行，否则将使用条件。‘true’
• clean：text，每次执行都重建拓扑图，默认false false

id	cnt	chk	ein	eout	the_geom
1					0101000020110F0000CE19510898216741808CB98B6D004F41
2					0101000020110F00002C431C4D9821674190D409202E004F41
3					0101000020110F0000B8D1001CBA21674130CB103769004F41
4					0101000020110F00006C9A77AA9721674120C9E50FC4004F41
5					0101000020110F0000E61DA7BA66216741E07A149EC5004F41
6					0101000020110F0000EC9E3C8E97216741B0D85F6EED004F41
7					0101000020110F0000744694CEAE21674160FE431AEA004F41
8					0101000020110F0000143FC652A1216741701283205B014F41
9					0101000020110F000082734670B5216741E0F21F825C014F41
10					0101000020110F0000B0506BE2BB216741907571F35C014F41
11					0101000020110F0000FC87F465BB21674120C05BB0EB004F41
12					0101000020110F0000C286A717DF216741F097DD3B5D014F41
13					0101000020110F0000182653A5D8216741C06D34E88C004F41
14					0101000020110F0000A089B0CB0C226741903177555A014F41
15					0101000020110F0000EE7C3FF1C12167419028ED5D5D014F41
16					0101000020110F0000F4FDD4AE982167412063EE827E014F41
17					0101000020110F0000F085C9D09821674120FDF60DAA014F41
18					0101000020110F0000083D9BC561216741B08BDB18A4014F41
19					0101000020110F0000D8F0F426B52167418026C27EBB014F41
20					0101000020110F0000623255BEC1216741E0D7812BE1014F41
21					0101000020110F0000D881730899216741A0DFBE6EF1014F41
22					0101000020110F00000022FDD4E5216741A0DFBE76ED014F41
23					0101000020110F00003AB4C8489921674170787AED43024F41
24					0101000020110F000052962116602167412051DACB3A024F41
25					0101000020110F0000141DC96199216741803F35BE9E024F41
26					0101000020110F0000F6065F9ADD216741E08C28F59B024F41
27					0101000020110F0000CAE53F829921674140795880B6024F41
28					0101000020110F0000ECC0396D5B216741F0263110BE024F41
29					0101000020110F000052DA1B629A216741505986505A034F41

字段介绍

id:	bigint 顶点的标识符。
cnt:	integer edge_table中引用此顶点的顶点数。See pgr_analyzeGraph.
chk:	integer 指示顶点可能有问题。See pgr_analyzeGraph.
ein:	integer edge_table中引用这个顶点的顶点数。See pgr_analyzeOneway.
eout:	integer edge_table中引用该顶点作为输出的顶点数。See pgr_analyzeOneway.
the_geom:	geometry Point geometry of the vertex：顶点的点几何。

查找联通性

此处联通性计算使用Dijkstra算法，其原理是找出两点的最短路径，如果能找到最短路径说明是联通的，并放回最短路径，如果找不到，说明不连通。

Dijkstra算法，由荷兰计算机科学家Edsger Dijkstra（上面的照片就是这位大佬！）于1956年提出。它是一种图搜索算法，它解决了非负代价边路径图的最短路径问题，即从起始顶点（start_vid）到结束顶点（end_vid）的最短路径。此算法可以与有向图或无向图一起使用。

select * from pgr_dijkstra('select id ,source,target,cost::double precision from testpipeline',28,14,directed:=false)

• edges sql Text,要进行分析的表及相关字段
• strart_vids 起点id
• end_vids 终点id
• directed参数的值，默认true，true计算过程考虑图的方向,false计算过程不考虑图的方向

查询结果

seq	path_sql	node	edge	cost	agg_cost
1	1	28	26	496.9394137	0
2	2	27	25	47.52752875	496.9394137
3	3	25	23	181.6831255	544.4669425
4	4	23	22	165.0023479	726.150068
5	5	21	19	142.7666976	891.1524158
6	6	17	16	87.09266423	1033.919113
7	7	16	14	98.92549714	1121.011778
8	8	8	7	160.9456115	1219.937275
9	9	9	8	51.57459883	1380.882886
10	10	10	12	48.47053948	1432.457485
11	11	15	13	233.2344497	1480.928025
12	12	12	11	365.6724458	1714.162474
13	13	14	-1	0	2079.83492

node节点顺序

edge 管线顺序