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.

_images/boost-inside.jpeg

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.

Where:

ANY-INTEGER

smallint, int, bigint

ANY-NUMERICAL

smallint, int, bigint, real, float

Result Columns

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.

Additional Examples

Example

From point \(1\) and vertex \(2\) to point \(3\) and vertex \(7\), 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

From point \(1\) and vertex \(2\) to point \(3\) and vertex \(7\), 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

From point \(1\) and vertex \(2\) to point \(3\) and vertex \(7\), 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.