pgr_extractVertices – Proposed¶
pgr_extractVertices
— Extracts the vertices information based on the source and target.
Warning
Proposed functions for next mayor release.
They are not officially in the current release.
They will likely officially be part of the next mayor release:
The functions make use of ANY-INTEGER and ANY-NUMERICAL
Name might not change. (But still can)
Signature might not change. (But still can)
Functionality might not change. (But still can)
pgTap tests have being done. But might need more.
Documentation might need refinement.
Availability
Version 3.3.0
Clasiffied as proposed function
Version 3.0.0
New experimental function
Description¶
This is an auxiliary function for extracting the vertex information of the set of edges of a graph.
When the edge identifier is given, then it will also calculate the in and out edges
Signatures¶
pgr_extractVertices(Edges SQL [, dryrun])
RETURNS SETOF (id, in_edges, out_edges, x, y, geom)
- Example
Extracting the vertex information
SELECT * FROM pgr_extractVertices(
'SELECT id, the_geom AS geom
FROM edge_table');
id | in_edges | out_edges | x | y | geom
----+----------+-----------+----------------+-----+--------------------------------------------
1 | | {6} | 0 | 2 | 010100000000000000000000000000000000000040
2 | | {17} | 0.5 | 3.5 | 0101000000000000000000E03F0000000000000C40
3 | {6} | {7} | 1 | 2 | 0101000000000000000000F03F0000000000000040
4 | {17} | | 1.999999999999 | 3.5 | 010100000068EEFFFFFFFFFF3F0000000000000C40
5 | | {1} | 2 | 0 | 010100000000000000000000400000000000000000
6 | {1} | {2,4} | 2 | 1 | 01010000000000000000000040000000000000F03F
7 | {4,7} | {8,10} | 2 | 2 | 010100000000000000000000400000000000000040
8 | {10} | {12,14} | 2 | 3 | 010100000000000000000000400000000000000840
9 | {14} | | 2 | 4 | 010100000000000000000000400000000000001040
10 | {2} | {3,5} | 3 | 1 | 01010000000000000000000840000000000000F03F
11 | {5,8} | {9,11} | 3 | 2 | 010100000000000000000008400000000000000040
12 | {11,12} | {13} | 3 | 3 | 010100000000000000000008400000000000000840
13 | | {18} | 3.5 | 2.3 | 01010000000000000000000C406666666666660240
14 | {18} | | 3.5 | 4 | 01010000000000000000000C400000000000001040
15 | {3} | {16} | 4 | 1 | 01010000000000000000001040000000000000F03F
16 | {9,16} | {15} | 4 | 2 | 010100000000000000000010400000000000000040
17 | {13,15} | | 4 | 3 | 010100000000000000000010400000000000000840
(17 rows)
Parameters¶
Parameter |
Type |
Description |
---|---|---|
Edges SQL |
|
The set of edges of the graph. It is an Inner Query as described below. |
dryrun |
|
Don’t process and get in a NOTICE the resulting query. |
Inner Query¶
When line geometry is known
Column |
Type |
Description |
---|---|---|
id |
|
(Optional) identifier of the edge. |
geom |
|
LINESTRING geometry of the edge. |
This inner query takes precedence over the next two inner query, therefore other columns are ignored when geom
column appears.
Ignored columns:
startpoint
endpoint
source
target
When vertex geometry is known
To use this inner query the column geom
should not be part of the set of columns.
Column |
Type |
Description |
---|---|---|
id |
|
(Optional) identifier of the edge. |
startpoint |
|
POINT geometry of the starting vertex. |
endpoint |
|
POINT geometry of the ending vertex. |
This inner query takes precedence over the next inner query,
therefore other columns are ignored when startpoint
and endpoint
columns appears.
Ignored columns:
source
target
When identifiers of vertices are known
To use this inner query the columns geom
, startpoint
and endpoint
should not be part of the set of columns.
Column |
Type |
Description |
---|---|---|
id |
|
(Optional) identifier of the edge. |
source |
|
Identifier of the first end point vertex of the edge. |
target |
|
Identifier of the second end point vertex of the edge. |
Result Columns¶
Rreturns set of (id, in_edges, out_edges, x, y, geom)
Column |
Type |
Description |
---|---|---|
id |
|
Identifier of the first end point vertex of the edge. |
in_edges |
|
|
out_edges |
|
|
x |
|
|
y |
|
|
geom |
|
|
Additional Examples¶
- Example 1
Dryrun execution
To get the query generated used to get the vertex information, use dryrun := true
.
The results can be used as base code to make a refinement based on the backend development needs.
SELECT * FROM pgr_extractVertices(
'SELECT id, the_geom AS geom FROM edge_table',
dryrun := true);
NOTICE:
WITH
main_sql AS (
SELECT id, the_geom AS geom FROM edge_table
),
the_out AS (
SELECT id::BIGINT AS out_edge, ST_StartPoint(geom) AS geom
FROM main_sql
),
agg_out AS (
SELECT array_agg(out_edge ORDER BY out_edge) AS out_edges, ST_x(geom) AS x, ST_Y(geom) AS y, geom
FROM the_out
GROUP BY geom
),
the_in AS (
SELECT id::BIGINT AS in_edge, ST_EndPoint(geom) AS geom
FROM main_sql
),
agg_in AS (
SELECT array_agg(in_edge ORDER BY in_edge) AS in_edges, ST_x(geom) AS x, ST_Y(geom) AS y, geom
FROM the_in
GROUP BY geom
),
the_points AS (
SELECT in_edges, out_edges, coalesce(agg_out.geom, agg_in.geom) AS geom
FROM agg_out
FULL OUTER JOIN agg_in USING (x, y)
)
SELECT row_number() over(ORDER BY ST_X(geom), ST_Y(geom)) AS id, in_edges, out_edges, ST_X(geom), ST_Y(geom), geom
FROM the_points;
id | in_edges | out_edges | x | y | geom
----+----------+-----------+---+---+------
(0 rows)
- Example 2
Creating a routing topology
Making sure the database does not have the
vertices_table
DROP TABLE IF EXISTS vertices_table; NOTICE: table "vertices_table" does not exist, skipping DROP TABLE
Cleaning up the columns of the rotuing topology to be created
UPDATE edge_table SET source = NULL, target = NULL, x1 = NULL, y1 = NULL, x2 = NULL, y2 = NULL; UPDATE 18
Creating the vertices table
SELECT * INTO vertices_table FROM pgr_extractVertices('SELECT id, the_geom AS geom FROM edge_table'); SELECT 17
Inspection of the vertices table
SELECT * FROM vertices_table; id | in_edges | out_edges | x | y | geom ----+----------+-----------+----------------+-----+-------------------------------------------- 1 | | {6} | 0 | 2 | 010100000000000000000000000000000000000040 2 | | {17} | 0.5 | 3.5 | 0101000000000000000000E03F0000000000000C40 3 | {6} | {7} | 1 | 2 | 0101000000000000000000F03F0000000000000040 4 | {17} | | 1.999999999999 | 3.5 | 010100000068EEFFFFFFFFFF3F0000000000000C40 5 | | {1} | 2 | 0 | 010100000000000000000000400000000000000000 6 | {1} | {2,4} | 2 | 1 | 01010000000000000000000040000000000000F03F 7 | {4,7} | {8,10} | 2 | 2 | 010100000000000000000000400000000000000040 8 | {10} | {12,14} | 2 | 3 | 010100000000000000000000400000000000000840 9 | {14} | | 2 | 4 | 010100000000000000000000400000000000001040 10 | {2} | {3,5} | 3 | 1 | 01010000000000000000000840000000000000F03F 11 | {5,8} | {9,11} | 3 | 2 | 010100000000000000000008400000000000000040 12 | {11,12} | {13} | 3 | 3 | 010100000000000000000008400000000000000840 13 | | {18} | 3.5 | 2.3 | 01010000000000000000000C406666666666660240 14 | {18} | | 3.5 | 4 | 01010000000000000000000C400000000000001040 15 | {3} | {16} | 4 | 1 | 01010000000000000000001040000000000000F03F 16 | {9,16} | {15} | 4 | 2 | 010100000000000000000010400000000000000040 17 | {13,15} | | 4 | 3 | 010100000000000000000010400000000000000840 (17 rows)
Creating the routing topology on the edge table
Updating the
source
informationWITH out_going AS ( SELECT id AS vid, unnest(out_edges) AS eid, x, y FROM vertices_table ) UPDATE edge_table SET source = vid, x1 = x, y1 = y FROM out_going WHERE id = eid; UPDATE 18
Updating the
target
informationWITH in_coming AS ( SELECT id AS vid, unnest(in_edges) AS eid, x, y FROM vertices_table ) UPDATE edge_table SET target = vid, x2 = x, y2 = y FROM in_coming WHERE id = eid; UPDATE 18
Inspection of the routing topology
SELECT id, source, target, x1, y1, x2, y2 FROM edge_table; id | source | target | x1 | y1 | x2 | y2 ----+--------+--------+-----+-----+----------------+----- 6 | 1 | 3 | 0 | 2 | 1 | 2 17 | 2 | 4 | 0.5 | 3.5 | 1.999999999999 | 3.5 1 | 5 | 6 | 2 | 0 | 2 | 1 4 | 6 | 7 | 2 | 1 | 2 | 2 7 | 3 | 7 | 1 | 2 | 2 | 2 10 | 7 | 8 | 2 | 2 | 2 | 3 14 | 8 | 9 | 2 | 3 | 2 | 4 2 | 6 | 10 | 2 | 1 | 3 | 1 5 | 10 | 11 | 3 | 1 | 3 | 2 8 | 7 | 11 | 2 | 2 | 3 | 2 11 | 11 | 12 | 3 | 2 | 3 | 3 12 | 8 | 12 | 2 | 3 | 3 | 3 18 | 13 | 14 | 3.5 | 2.3 | 3.5 | 4 3 | 10 | 15 | 3 | 1 | 4 | 1 9 | 11 | 16 | 3 | 2 | 4 | 2 16 | 15 | 16 | 4 | 1 | 4 | 2 13 | 12 | 17 | 3 | 3 | 4 | 3 15 | 16 | 17 | 4 | 2 | 4 | 3 (18 rows)
See Also¶
Topology - Family of Functions for an overview of a topology for routing algorithms.
pgr_createVerticesTable to create a topology based on the geometry.
Indices and tables