pgr_withPointsCost¶

Name¶

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

Note

This is a proposed function for version 2.3.

Is not officially in the version 2.2 release.

Boost Graph Inside

Synopsis¶

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

Characteristics:¶

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: \(O(| start\_vids | * (V \log V + E))\)

Signature Summary¶

pgr_withPointsCost(edges_sql, points_sql, start_vid, end_vid, directed, driving_side)
pgr_withPointsCost(edges_sql, points_sql, start_vid, end_vids, directed, driving_side)
pgr_withPointsCost(edges_sql, points_sql, start_vids, end_vid, directed, driving_side)
pgr_withPointsCost(edges_sql, points_sql, start_vids, end_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 family of functions.

Signatures¶

Minimal Usage¶

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.

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

Example:

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, start_vid, end_vid,
    directed:=true, driving_side:='b')
RETURNS SET OF (seq, node, edge, cost, agg_cost)

Example:

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, start_vid, end_vids,
    directed:=true, driving_side:='b')
RETURNS SET OF (start_vid, end_vid, agg_cost)

Example:

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, start_vids, end_vid,
    directed:=true, driving_side:='b')
RETURNS SET OF (start_vid, end_vid, agg_cost)

Example:

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, start_vids, end_vids,
    directed:=true, driving_side:='b')
RETURNS SET OF (start_vid, end_vid, agg_cost)

Example:

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)

Description of the Signatures¶

Description of the Edges SQL query¶

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

Column	Type	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), If negative: edge (source, target) does not exist, therefore it’s not part of the graph.
reverse_cost	`ANY-NUMERICAL`	(optional) Weight of the edge (target, source), If negative: edge (target, source) does not exist, therefore it’s not part of the graph.

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. 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.

Where:

ANY-INTEGER:	smallint, int, bigint
ANY-NUMERICAL:	smallint, int, bigint, real, float

Description of the parameters of the signatures¶

Parameter	Type	Description
edges_sql	`TEXT`	Edges SQL query as decribed above.
points_sql	`TEXT`	Points SQL query as decribed 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.

Description of the return values¶

Returns set of (start_vid, end_vid, agg_cost)

Column	Type	Description
start_vid	`BIGINT`	Identifier of the starting vertex. When negative: is a point’s pid.
end_vid	`BIGINT`	Identifier of the ending point. When negative: is a point’s pid.
agg_cost	`FLOAT`	Aggregate cost from `start_vid` to `end_vid`.

Examples¶

Example:	With right side driving topology.

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],
        driving_side := 'l');
 start_pid | end_pid | agg_cost 
-----------+---------+----------
        -1 |      -3 |      3.2
        -1 |       7 |      3.6
         2 |      -3 |      2.6
         2 |       7 |        3
(4 rows)

Example:	With left side driving topology.

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],
        driving_side := 'r');
 start_pid | end_pid | agg_cost 
-----------+---------+----------
        -1 |      -3 |        4
        -1 |       7 |      4.4
         2 |      -3 |      2.6
         2 |       7 |        3
(4 rows)

Example:	Does not matter driving side.

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],
        driving_side := 'b');
 start_pid | end_pid | agg_cost 
-----------+---------+----------
        -1 |      -3 |      3.2
        -1 |       7 |      3.6
         2 |      -3 |      2.6
         2 |       7 |        3
(4 rows)

The queries use the Sample Data network.

History

Proposed in version 2.2

pgRouting Manual (2.2)