pgr_withPointsCost - Proposed¶

pgr_withPointsCost - Calculates the shortest path and returns only the aggregate cost of the shortest path(s) found, for the combination of points given.

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.

Boost Graph Inside

Availability

Version 2.2.0
- New proposed function

Support

Description¶

Modify the graph to include points defined by points_sql. Using Dijkstra algorithm, return only the aggregate cost of the shortest path(s) found.

The main characteristics are:

It does not return a path.
Returns the sum of the costs of the shortest path for pair combination of vertices in the modified graph.
Vertices of the graph are:
- positive when it belongs to the edges_sql
- negative when it belongs to the points_sql
Process is done only on edges with positive costs.
Values are returned when there is a path.
- The returned values are in the form of a set of (start_vid, end_vid, agg_cost).
- When the starting vertex and ending vertex are the same, there is no path.
  - The agg_cost in 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 in the non included values (u, v) is \(\infty\)
If the values returned are stored in a table, the unique index would be the pair: (start_vid, end_vid).
For undirected graphs, the results are symmetric.
- The agg_cost of (u, v) is the same as for (v, u).
For optimization purposes, any duplicated value in the start_vids or end_vids is ignored.
The returned values are ordered:
- start_vid ascending
- end_vid ascending
Running time: \(O(| start\_vids | * (V \log V + E))\)

Signatures¶

Summary

pgr_withPointsCost(edges_sql, points_sql, from_vid,  to_vid  [, directed] [, driving_side])
pgr_withPointsCost(edges_sql, points_sql, from_vid,  to_vids [, directed] [, driving_side])
pgr_withPointsCost(edges_sql, points_sql, from_vids, to_vid  [, directed] [, driving_side])
pgr_withPointsCost(edges_sql, points_sql, from_vids, to_vids [, directed] [, driving_side])
RETURNS SET OF (start_vid, end_vid, agg_cost)

Note

There is no details flag, unlike the other members of the withPoints family of functions.

Using defaults

pgr_withPointsCost(edges_sql, points_sql, start_vid, end_vid)
RETURNS SET OF (start_vid, end_vid, agg_cost)

Example:	From point \(1\) to point \(3\)

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.

SELECT * FROM pgr_withPointsCost(
    'SELECT id, source, target, cost, reverse_cost FROM edge_table ORDER BY id',
    'SELECT pid, edge_id, fraction, side from pointsOfInterest',
    -1, -3);
 start_pid | end_pid | agg_cost
-----------+---------+----------
        -1 |      -3 |      3.2
(1 row)

One to One¶

pgr_withPointsCost(edges_sql, points_sql, from_vid,  to_vid  [, directed] [, driving_side])
RETURNS SET OF (seq, node, edge, cost, agg_cost)

Example:	From point \(1\) to vertex \(3\) on an undirected graph.

SELECT * FROM pgr_withPointsCost(
    'SELECT id, source, target, cost, reverse_cost FROM edge_table ORDER BY id',
    'SELECT pid, edge_id, fraction, side from pointsOfInterest',
    -1, 3,
    directed := false);
 start_pid | end_pid | agg_cost
-----------+---------+----------
        -1 |       3 |      1.6
(1 row)

One to Many¶

pgr_withPointsCost(edges_sql, points_sql, from_vid,  to_vids [, directed] [, driving_side])
RETURNS SET OF (start_vid, end_vid, agg_cost)

Example:	From point \(1\) to point \(3\) and vertex \(5\) on a directed graph.

SELECT * FROM pgr_withPointsCost(
    '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]);
 start_pid | end_pid | agg_cost
-----------+---------+----------
        -1 |      -3 |      3.2
        -1 |       5 |      1.6
(2 rows)

Many to One¶

pgr_withPointsCost(edges_sql, points_sql, from_vids, to_vid  [, directed] [, driving_side])
RETURNS SET OF (start_vid, end_vid, agg_cost)

Example:	From point \(1\) and vertex \(2\) to point \(3\) on a directed graph.

SELECT * FROM pgr_withPointsCost(
    '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);
 start_pid | end_pid | agg_cost
-----------+---------+----------
        -1 |      -3 |      3.2
         2 |      -3 |      2.6
(2 rows)

Many to Many¶

pgr_withPointsCost(edges_sql, points_sql, from_vids, to_vids [, directed] [, driving_side])
RETURNS SET OF (start_vid, end_vid, agg_cost)

Example:	From point \(1\) and vertex \(2\) to point \(3\) and vertex \(7\) on a directed graph.

SELECT * FROM pgr_withPointsCost(
    '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]);
 start_pid | end_pid | agg_cost
-----------+---------+----------
        -1 |      -3 |      3.2
        -1 |       7 |      3.6
         2 |      -3 |      2.6
         2 |       7 |        3
(4 rows)

Parameters¶

Parameter	Type	Description
edges_sql	`TEXT`	Edges SQL query as described above.
points_sql	`TEXT`	Points SQL query as described above.
start_vid	`ANY-INTEGER`	Starting vertex identifier. When negative: is a point’s pid.
end_vid	`ANY-INTEGER`	Ending vertex identifier. When negative: is a point’s pid.
start_vids	`ARRAY[ANY-INTEGER]`	Array of identifiers of starting vertices. When negative: is a point’s pid.
end_vids	`ARRAY[ANY-INTEGER]`	Array of identifiers of ending vertices. When negative: is a point’s pid.
directed	`BOOLEAN`	(optional). When `false` the graph is considered as Undirected. Default is `true` which considers the graph as Directed.
driving_side	`CHAR`	(optional) Value in [‘b’, ‘r’, ‘l’, NULL] indicating if the driving side is: In the right or left or If it doesn’t matter with ‘b’ or NULL. If column not present ‘b’ is considered.

Inner query¶

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.