pgr_nodeNetwork¶
pgr_nodeNetwork - 网络边表的节点。
- 作者:
Nicolas Ribot
- 版权:
Nicolas Ribot，源代码根据 MIT-X 许可证发布。
该函数从非"noded"网络表中读取边，并将"noded"边写入新表中。
| pgr_nodenetwork(edge_table, tolerance, [options]) | options:[id, text the_geom, table_ending, rows_where, outall]| RETURNSTEXT
可用性
版本2.0.0
Official function.
描述¶
主要特点是：
将 GIS 数据引入 pgRouting 的一个常见问题是数据通常没有正确“节点化”。 这将创建无效的拓扑，从而导致路由不正确。
我们所说的 "noded"是指在道路网络的每个交叉口，所有边缘都将被分成单独的路段。 在某些情况下，例如天桥和地下通道交叉口，您无法从天桥穿越到地下通道，但此功能无法检测和适应这些情况。
该函数读取 edge_table``表，该表具有主键列 ``id 和名为``the_geom`` 的几何列，并将其中的所有段与所有其他段相交，然后创建表 edge_table_noded。 它使用``tolerance`` 来决定容差内的多个节点被视为同一节点。
参数¶
- edge_table:
text网络表的名称（可能包含模式名称）- tolerance:
float8重合点公差（以投影单位表示）dd- id:
text网络表的主键列名称。 默认值为``id``。- the_geom:
text``网络表的几何列名称。 默认值为``the_geom。- table_ending:
text``新表的后缀。 默认值是``noded。
输出表中将包含 edge_table_noded 内容
- id:
bigint表的唯一标识符- old_id:
bigintIdentifier of the edge in original table- sub_id:
integer原边的段号- source:
integer与 pgr_createTopology 函数一起使用的空source列- target:
integer与 pgr_createTopology 函数一起使用的空target列- the geom:
geometry节点网络的几何列
示例¶
让我们为 示例数据 中的数据创建拓扑
SELECT pgr_createTopology('edges', 0.001, 'geom', clean := TRUE);
NOTICE: PROCESSING:
NOTICE: pgr_createTopology('edges', 0.001, 'geom', 'id', 'source', 'target', rows_where := 'true', clean := t)
NOTICE: Performing checks, please wait .....
NOTICE: Creating Topology, Please wait...
NOTICE: -------------> TOPOLOGY CREATED FOR 18 edges
NOTICE: Rows with NULL geometry or NULL id: 0
NOTICE: Vertices table for table public.edges is: public.edges_vertices_pgr
NOTICE: ----------------------------------------------
pgr_createtopology
--------------------
OK
(1 row)
现在我们可以分析网络了。
SELECT pgr_analyzegraph('edges', 0.001, 'geom');
NOTICE: PROCESSING:
NOTICE: pgr_analyzeGraph('edges',0.001,'geom','id','source','target','true')
NOTICE: Performing checks, please wait ...
NOTICE: Analyzing for dead ends. Please wait...
NOTICE: Analyzing for gaps. Please wait...
NOTICE: Analyzing for isolated edges. Please wait...
NOTICE: Analyzing for ring geometries. Please wait...
NOTICE: Analyzing for intersections. Please wait...
NOTICE: ANALYSIS RESULTS FOR SELECTED EDGES:
NOTICE: Isolated segments: 2
NOTICE: Dead ends: 7
NOTICE: Potential gaps found near dead ends: 1
NOTICE: Intersections detected: 1
NOTICE: Ring geometries: 0
pgr_analyzegraph
------------------
OK
(1 row)
分析告诉我们，网络存在缺口和交叉点。 我们尝试使用以下方法解决该问题：
SELECT pgr_nodeNetwork('edges', 0.001, the_geom => 'geom');
NOTICE: PROCESSING:
NOTICE: id: id
NOTICE: the_geom: geom
NOTICE: table_ending: noded
NOTICE: rows_where:
NOTICE: outall: f
NOTICE: pgr_nodeNetwork('edges', 0.001, 'id', 'geom', 'noded', '', f)
NOTICE: Performing checks, please wait .....
NOTICE: Processing, please wait .....
NOTICE: Split Edges: 3
NOTICE: Untouched Edges: 15
NOTICE: Total original Edges: 18
NOTICE: Edges generated: 6
NOTICE: Untouched Edges: 15
NOTICE: Total New segments: 21
NOTICE: New Table: public.edges_noded
NOTICE: ----------------------------------
pgr_nodenetwork
-----------------
OK
(1 row)
检查生成的表，我们可以看到边 13,14 和 18 已被分段
SELECT old_id, sub_id FROM edges_noded ORDER BY old_id, sub_id;
old_id | sub_id
--------+--------
1 | 1
2 | 1
3 | 1
4 | 1
5 | 1
6 | 1
7 | 1
8 | 1
9 | 1
10 | 1
11 | 1
12 | 1
13 | 1
13 | 2
14 | 1
14 | 2
15 | 1
16 | 1
17 | 1
18 | 1
18 | 2
(21 rows)
我们可以创建新网络的拓扑
SELECT pgr_createTopology('edges_noded', 0.001, 'geom');
NOTICE: PROCESSING:
NOTICE: pgr_createTopology('edges_noded', 0.001, 'geom', 'id', 'source', 'target', rows_where := 'true', clean := f)
NOTICE: Performing checks, please wait .....
NOTICE: Creating Topology, Please wait...
NOTICE: -------------> TOPOLOGY CREATED FOR 21 edges
NOTICE: Rows with NULL geometry or NULL id: 0
NOTICE: Vertices table for table public.edges_noded is: public.edges_noded_vertices_pgr
NOTICE: ----------------------------------------------
pgr_createtopology
--------------------
OK
(1 row)
现在我们来分析一下新的拓扑
SELECT pgr_analyzegraph('edges_noded', 0.001, 'geom');
NOTICE: PROCESSING:
NOTICE: pgr_analyzeGraph('edges_noded',0.001,'geom','id','source','target','true')
NOTICE: Performing checks, please wait ...
NOTICE: Analyzing for dead ends. Please wait...
NOTICE: Analyzing for gaps. Please wait...
NOTICE: Analyzing for isolated edges. Please wait...
NOTICE: Analyzing for ring geometries. Please wait...
NOTICE: Analyzing for intersections. Please wait...
NOTICE: ANALYSIS RESULTS FOR SELECTED EDGES:
NOTICE: Isolated segments: 0
NOTICE: Dead ends: 6
NOTICE: Potential gaps found near dead ends: 0
NOTICE: Intersections detected: 0
NOTICE: Ring geometries: 0
pgr_analyzegraph
------------------
OK
(1 row)
图片¶
之前的图像
后面的图像
比较结果¶
与原始edge_table中的分析相比，我们看到了这一点。
前 |
后 |
|
|---|---|---|
表名 |
edge_table |
edge_table_noded |
字段 |
所有原始字段 |
仅具有进行拓扑分析的基本字段 |
死端 |
边 17 的右侧节点是一个死端，因为没有其他边共享同一节点。 （cnt=1） |
有 1 个死端的边：1-1 ,6-1,14-2, 18-1 17-1 18-2 |
孤立的片段 |
two isolated segments: 17 and 18 both they have 2 dead ends |
|
差距 |
边 17 和边 14 之间有间隙，因为边 14 靠近边 17 的右侧节点 |
边缘14 被分段了，现在边缘14-1、14-2 和 17 共享同一个节点。容差值已被考虑 |
交叉口 |
边 13 和 18 相交 |
边被分段，所以，现在在交点处有一个节点，并且以下边共享它： 13-1 13-2 18-1 18-2 |
现在，我们将包括段 13-1、13-2、14-1、14-2、18-1 和 18-2 到我们的边表中，并复制 dir、cost 和 reverse cost 的数据，按照以下步骤进行：
在边表中添加一列old_id，该列将跟踪原始边的id
仅插入分段边，即 max(sub_id) >1 的边
alter table edges drop column if exists old_id;
NOTICE: column "old_id" of relation "edges" does not exist, skipping
ALTER TABLE
alter table edges add column old_id integer;
ALTER TABLE
insert into edges (old_id, cost, reverse_cost, geom)
(with
segmented as (select old_id,count(*) as i from edges_noded group by old_id)
select segments.old_id, cost, reverse_cost, segments.geom
from edges as edges join edges_noded as segments on (edges.id = segments.old_id)
where edges.id in (select old_id from segmented where i>1) );
INSERT 0 6
我们重新创建拓扑：
SELECT pgr_createTopology('edges', 0.001, 'geom');
NOTICE: PROCESSING:
NOTICE: pgr_createTopology('edges', 0.001, 'geom', 'id', 'source', 'target', rows_where := 'true', clean := f)
NOTICE: Performing checks, please wait .....
NOTICE: Creating Topology, Please wait...
NOTICE: -------------> TOPOLOGY CREATED FOR 6 edges
NOTICE: Rows with NULL geometry or NULL id: 0
NOTICE: Vertices table for table public.edges is: public.edges_vertices_pgr
NOTICE: ----------------------------------------------
pgr_createtopology
--------------------
OK
(1 row)
为了获得与edge_table_noded的拓扑相同的分析结果，我们执行以下查询：
SELECT pgr_analyzegraph('edges', 0.001, 'geom', rows_where:='id not in (select old_id from edges where old_id is not null)');
NOTICE: PROCESSING:
NOTICE: pgr_analyzeGraph('edges',0.001,'geom','id','source','target','id not in (select old_id from edges where old_id is not null)')
NOTICE: Performing checks, please wait ...
NOTICE: Analyzing for dead ends. Please wait...
NOTICE: Analyzing for gaps. Please wait...
NOTICE: Analyzing for isolated edges. Please wait...
NOTICE: Analyzing for ring geometries. Please wait...
NOTICE: Analyzing for intersections. Please wait...
NOTICE: ANALYSIS RESULTS FOR SELECTED EDGES:
NOTICE: Isolated segments: 0
NOTICE: Dead ends: 6
NOTICE: Potential gaps found near dead ends: 0
NOTICE: Intersections detected: 0
NOTICE: Ring geometries: 0
pgr_analyzegraph
------------------
OK
(1 row)
为了获得与原始edge_table相同的分析结果，我们执行以下查询：
SELECT pgr_analyzegraph('edges', 0.001, 'geom', rows_where:='old_id is null');
NOTICE: PROCESSING:
NOTICE: pgr_analyzeGraph('edges',0.001,'geom','id','source','target','old_id is null')
NOTICE: Performing checks, please wait ...
NOTICE: Analyzing for dead ends. Please wait...
NOTICE: Analyzing for gaps. Please wait...
NOTICE: Analyzing for isolated edges. Please wait...
NOTICE: Analyzing for ring geometries. Please wait...
NOTICE: Analyzing for intersections. Please wait...
NOTICE: ANALYSIS RESULTS FOR SELECTED EDGES:
NOTICE: Isolated segments: 2
NOTICE: Dead ends: 7
NOTICE: Potential gaps found near dead ends: 1
NOTICE: Intersections detected: 1
NOTICE: Ring geometries: 0
pgr_analyzegraph
------------------
OK
(1 row)
或者我们可以分析所有内容，因为也许边 18 是立交桥，边 14 是地下通道，还有一个街道水平交汇处，边 17 和 13 也会发生同样的情况。
SELECT pgr_analyzegraph('edges', 0.001, 'geom');
NOTICE: PROCESSING:
NOTICE: pgr_analyzeGraph('edges',0.001,'geom','id','source','target','true')
NOTICE: Performing checks, please wait ...
NOTICE: Analyzing for dead ends. Please wait...
NOTICE: Analyzing for gaps. Please wait...
NOTICE: Analyzing for isolated edges. Please wait...
NOTICE: Analyzing for ring geometries. Please wait...
NOTICE: Analyzing for intersections. Please wait...
NOTICE: ANALYSIS RESULTS FOR SELECTED EDGES:
NOTICE: Isolated segments: 0
NOTICE: Dead ends: 3
NOTICE: Potential gaps found near dead ends: 0
NOTICE: Intersections detected: 5
NOTICE: Ring geometries: 0
pgr_analyzegraph
------------------
OK
(1 row)
另请参阅¶
Topology - 函数族 用于概述路由算法的拓扑。 pgr_analyzeOneWay 分析边方向性的方法。 pgr_createTopology 根据几何图创建拓扑。 pgr_analyzeGraph 分析边表的边和顶点。
索引和表格