pgr_withPoints - Proposed¶

Name¶

pgr_withPoints - Returns the shortest path in a graph with additional temporary vertices.

Warning

These are 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.

Boost Graph Inside

Availability: 2.2.0

Synopsis¶

Modify the graph to include points defined by points_sql. Using Dijkstra algorithm, find the shortest path(s)

Characteristics:¶

The main Characteristics are:

Process is done only on edges with positive costs.

Vertices of the graph are:

positive when it belongs to the edges_sql

negative when it belongs to the points_sql

Values are returned when there is a path.

When the starting vertex and ending vertex are the same, there is no path.

The agg_cost the non included values (v, v) is 0

When the starting vertex and ending vertex are the different and there is no path:

The agg_cost the non included values (u, v) is ∞

For optimization purposes, any duplicated value in the start_vids or end_vids are ignored.

The returned values are ordered:

start_vid ascending

end_vid ascending

Running time: \(O(|start\_vids|∗(V \log V + E))\)

Signature Summary¶

pgr_withPoints(edges_sql, points_sql, start_vid, end_vid)
pgr_withPoints(edges_sql, points_sql, start_vid, end_vid, directed, driving_side, details)
pgr_withPoints(edges_sql, points_sql, start_vid, end_vids, directed, driving_side, details)
pgr_withPoints(edges_sql, points_sql, start_vids, end_vid, directed, driving_side, details)
pgr_withPoints(edges_sql, points_sql, start_vids, end_vids, directed, driving_side, details)
RETURNS SET OF (seq, path_seq, [start_vid,] [end_vid,] node, edge, cost, agg_cost)

Signatures¶

Minimal Use¶

The minimal signature:

Is for a directed graph.
The driving side is set as b both. So arriving/departing to/from the point(s) can be in any direction.
No details are given about distance of other points of points_sql query.

pgr_withPoints(edges_sql, points_sql, start_vid, end_vid)
RETURNS SET OF (seq, path_seq, node, edge, cost, agg_cost)

Example:	From point 1 to point 3

SELECT * FROM pgr_withPoints(
    'SELECT id, source, target, cost, reverse_cost FROM edge_table ORDER BY id',
    'SELECT pid, edge_id, fraction, side from pointsOfInterest',
    -1, -3);
 seq | path_seq | node | edge | cost | agg_cost 
-----+----------+------+------+------+----------
   1 |        1 |   -1 |    1 |  0.6 |        0
   2 |        2 |    2 |    4 |    1 |      0.6
   3 |        3 |    5 |   10 |    1 |      1.6
   4 |        4 |   10 |   12 |  0.6 |      2.6
   5 |        5 |   -3 |   -1 |    0 |      3.2
(5 rows)

One to One¶

pgr_withPoints(edges_sql, points_sql, start_vid, end_vid,
    directed:=true, driving_side:='b', details:=false)
RETURNS SET OF (seq, path_seq, node, edge, cost, agg_cost)

Example:	From point 1 to vertex 3

SELECT * FROM pgr_withPoints(
    'SELECT id, source, target, cost, reverse_cost FROM edge_table ORDER BY id',
    'SELECT pid, edge_id, fraction, side from pointsOfInterest',
    -1, 3,
    details := true);
 seq | path_seq | node | edge | cost | agg_cost 
-----+----------+------+------+------+----------
   1 |        1 |   -1 |    1 |  0.6 |        0
   2 |        2 |    2 |    4 |  0.7 |      0.6
   3 |        3 |   -6 |    4 |  0.3 |      1.3
   4 |        4 |    5 |    8 |    1 |      1.6
   5 |        5 |    6 |    9 |    1 |      2.6
   6 |        6 |    9 |   16 |    1 |      3.6
   7 |        7 |    4 |    3 |    1 |      4.6
   8 |        8 |    3 |   -1 |    0 |      5.6
(8 rows)

One to Many¶

pgr_withPoints(edges_sql, points_sql, start_vid, end_vids,
    directed:=true, driving_side:='b', details:=false)
RETURNS SET OF (seq, path_seq, end_vid, node, edge, cost, agg_cost)

Example:	From point 1 to point 3 and vertex 5

SELECT * FROM pgr_withPoints(
    'SELECT id, source, target, cost, reverse_cost FROM edge_table ORDER BY id',
    'SELECT pid, edge_id, fraction, side from pointsOfInterest',
    -1, ARRAY[-3,5]);
 seq | path_seq | end_pid | node | edge | cost | agg_cost 
-----+----------+---------+------+------+------+----------
   1 |        1 |      -3 |   -1 |    1 |  0.6 |        0
   2 |        2 |      -3 |    2 |    4 |    1 |      0.6
   3 |        3 |      -3 |    5 |   10 |    1 |      1.6
   4 |        4 |      -3 |   10 |   12 |  0.6 |      2.6
   5 |        5 |      -3 |   -3 |   -1 |    0 |      3.2
   6 |        1 |       5 |   -1 |    1 |  0.6 |        0
   7 |        2 |       5 |    2 |    4 |    1 |      0.6
   8 |        3 |       5 |    5 |   -1 |    0 |      1.6
(8 rows)

Many to One¶

pgr_withPoints(edges_sql, points_sql, start_vids, end_vid,
    directed:=true, driving_side:='b', details:=false)
RETURNS SET OF (seq, path_seq, start_vid, node, edge, cost, agg_cost)

Example:	From point 1 and vertex 2 to point 3

SELECT * FROM pgr_withPoints(
    'SELECT id, source, target, cost, reverse_cost FROM edge_table ORDER BY id',
    'SELECT pid, edge_id, fraction, side from pointsOfInterest',
    ARRAY[-1,2], -3);
 seq | path_seq | start_pid | node | edge | cost | agg_cost 
-----+----------+-----------+------+------+------+----------
   1 |        1 |        -1 |   -1 |    1 |  0.6 |        0
   2 |        2 |        -1 |    2 |    4 |    1 |      0.6
   3 |        3 |        -1 |    5 |   10 |    1 |      1.6
   4 |        4 |        -1 |   10 |   12 |  0.6 |      2.6
   5 |        5 |        -1 |   -3 |   -1 |    0 |      3.2
   6 |        1 |         2 |    2 |    4 |    1 |        0
   7 |        2 |         2 |    5 |   10 |    1 |        1
   8 |        3 |         2 |   10 |   12 |  0.6 |        2
   9 |        4 |         2 |   -3 |   -1 |    0 |      2.6
(9 rows)

Many to Many¶

pgr_withPoints(edges_sql, points_sql, start_vids, end_vids,
    directed:=true, driving_side:='b', details:=false)
RETURNS SET OF (seq, path_seq, start_vid, end_vid, node, edge, cost, agg_cost)

Example:	From point 1 and vertex 2 to point 3 and vertex 7

SELECT * FROM pgr_withPoints(
    'SELECT id, source, target, cost, reverse_cost FROM edge_table ORDER BY id',
    'SELECT pid, edge_id, fraction, side from pointsOfInterest',
    ARRAY[-1,2], ARRAY[-3,7]);
 seq | path_seq | start_pid | end_pid | node | edge | cost | agg_cost 
-----+----------+-----------+---------+------+------+------+----------
|        1 |        -1 |      -3 |   -1 |    1 |  0.6 |        0
|        2 |        -1 |      -3 |    2 |    4 |    1 |      0.6
|        3 |        -1 |      -3 |    5 |   10 |    1 |      1.6
|        4 |        -1 |      -3 |   10 |   12 |  0.6 |      2.6
|        5 |        -1 |      -3 |   -3 |   -1 |    0 |      3.2
|        1 |        -1 |       7 |   -1 |    1 |  0.6 |        0
|        2 |        -1 |       7 |    2 |    4 |    1 |      0.6
|        3 |        -1 |       7 |    5 |    7 |    1 |      1.6
|        4 |        -1 |       7 |    8 |    6 |    1 |      2.6
|        5 |        -1 |       7 |    7 |   -1 |    0 |      3.6
|        1 |         2 |      -3 |    2 |    4 |    1 |        0
|        2 |         2 |      -3 |    5 |   10 |    1 |        1
|        3 |         2 |      -3 |   10 |   12 |  0.6 |        2
|        4 |         2 |      -3 |   -3 |   -1 |    0 |      2.6
|        1 |         2 |       7 |    2 |    4 |    1 |        0
|        2 |         2 |       7 |    5 |    7 |    1 |        1
|        3 |         2 |       7 |    8 |    6 |    1 |        2
|        4 |         2 |       7 |    7 |   -1 |    0 |        3
(18 rows)

Description of the Signatures¶

Description of the edges_sql query for dijkstra like functions¶

edges_sql:	an SQL query, which should return a set of rows with the following columns:

Column	Type	Default	Description
id	`ANY-INTEGER`		Identifier of the edge.
source	`ANY-INTEGER`		Identifier of the first end point vertex of the edge.
target	`ANY-INTEGER`		Identifier of the second end point vertex of the edge.
cost	`ANY-NUMERICAL`		Weight of the edge (source, target) When negative: edge (source, target) does not exist, therefore it’s not part of the graph.
reverse_cost	`ANY-NUMERICAL`	-1	Weight of the edge (target, source), When negative: edge (target, source) does not exist, therefore it’s not part of the graph.

Where:

ANY-INTEGER:	SMALLINT, INTEGER, BIGINT
ANY-NUMERICAL:	SMALLINT, INTEGER, BIGINT, REAL, FLOAT

Description of the Points SQL query¶

points_sql:	an SQL query, which should return a set of rows with the following columns:

Column	Type	Description
pid	`ANY-INTEGER`	(optional) Identifier of the point. If column present, it can not be NULL. If column not present, a sequential identifier will be given automatically.
edge_id	`ANY-INTEGER`	Identifier of the “closest” edge to the point.
fraction	`ANY-NUMERICAL`	Value in <0,1> that indicates the relative postition from the first end point of the edge.
side	`CHAR`	(optional) Value in [‘b’, ‘r’, ‘l’, NULL] indicating if the point is: In the right, left of the edge or If it doesn’t matter with ‘b’ or NULL. If column not present ‘b’ is considered.