pgr_withPointsDD - Proposed

pgr_withPointsDD - Returns the driving distance from a starting point.

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 and using Dijkstra algorithm, extracts all the nodes and points that have costs less than or equal to the value distance from the starting point. The edges extracted will conform the corresponding spanning tree.

Signatures

Summary

pgr_withPointsDD(edges_sql, points_sql, from_vids, distance [, directed] [, driving_side] [, details] [, equicost])
RETURNS SET OF (seq, node, edge, cost, agg_cost)

Using defaults

  • 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 the query.

pgr_withPointsDD(edges_sql, points_sql, start_vid, distance)
RETURNS SET OF (seq, node, edge, cost, agg_cost)
Example

From point \(1\) with \(agg\_cost <= 3.8\)

  • 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 the query.

SELECT * FROM pgr_withPointsDD(
    'SELECT id, source, target, cost, reverse_cost FROM edge_table ORDER BY id',
    'SELECT pid, edge_id, fraction, side from pointsOfInterest',
    -1, 3.8);
 seq | node | edge | cost | agg_cost
-----+------+------+------+----------
   1 |   -1 |   -1 |    0 |        0
   2 |    1 |    1 |  0.4 |      0.4
   3 |    2 |    1 |  0.6 |      0.6
   4 |    5 |    4 |    1 |      1.6
   5 |    6 |    8 |    1 |      2.6
   6 |    8 |    7 |    1 |      2.6
   7 |   10 |   10 |    1 |      2.6
   8 |    7 |    6 |    1 |      3.6
   9 |    9 |    9 |    1 |      3.6
  10 |   11 |   11 |    1 |      3.6
  11 |   13 |   14 |    1 |      3.6
(11 rows)

Single vertex

Finds the driving distance depending on the optional parameters setup.

pgr_withPointsDD(edges_sql, points_sql, from_vid,  distance [, directed] [, driving_side] [, details])
RETURNS SET OF (seq, node, edge, cost, agg_cost)
Example

Right side driving topology, from point \(1\) with \(agg\_cost <= 3.8\)

SELECT * FROM pgr_withPointsDD(
    'SELECT id, source, target, cost, reverse_cost FROM edge_table ORDER BY id',
    'SELECT pid, edge_id, fraction, side from pointsOfInterest',
    -1, 3.8,
    driving_side := 'r',
    details := true);
 seq | node | edge | cost | agg_cost
-----+------+------+------+----------
   1 |   -1 |   -1 |    0 |        0
   2 |    1 |    1 |  0.4 |      0.4
   3 |    2 |    1 |    1 |      1.4
   4 |   -6 |    4 |  0.7 |      2.1
   5 |    5 |    4 |  0.3 |      2.4
   6 |    6 |    8 |    1 |      3.4
   7 |    8 |    7 |    1 |      3.4
   8 |   10 |   10 |    1 |      3.4
(8 rows)

Multiple vertices

Finds the driving distance depending on the optional parameters setup.

pgr_withPointsDD(edges_sql, points_sql, from_vids, distance [, directed] [, driving_side] [, details] [, equicost])
RETURNS SET OF (seq, node, edge, cost, agg_cost)

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 point id

distance

ANY-NUMERICAL

Distance from the start_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.

details

BOOLEAN

(optional). When true the results will include the driving distance to the points with in the distance. Default is false which ignores other points of the points_sql.

equicost

BOOLEAN

(optional). When true the nodes will only appear in the closest start_v list. Default is false which resembles several calls using the single starting point signatures. Tie brakes are arbitrary.

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

seq

INT

row sequence.

node

BIGINT

Identifier of the node within the Distance from start_pid. If details =: true a negative value is the identifier of a point.

edge

BIGINT

Identifier of the edge used to go from node to the next node in the path sequence.
  • -1 when start_vid = node.

cost

FLOAT

Cost to traverse edge.
  • 0 when start_vid = node.

agg_cost

FLOAT

Aggregate cost from start_vid to node.
  • 0 when start_vid = node.

Additional Examples

Examples for queries marked as directed with cost and reverse_cost columns.

The examples in this section use the following Network for queries marked as directed and cost and reverse_cost columns are used

Example

Left side driving topology from point \(1\) with \(agg\_cost <= 3.8\), with details

SELECT * FROM pgr_withPointsDD(
    'SELECT id, source, target, cost, reverse_cost FROM edge_table ORDER BY id',
    'SELECT pid, edge_id, fraction, side from pointsOfInterest',
    -1, 3.8,
    driving_side := 'l',
    details := true);
 seq | node | edge | cost | agg_cost
-----+------+------+------+----------
   1 |   -1 |   -1 |    0 |        0
   2 |    2 |    1 |  0.6 |      0.6
   3 |   -6 |    4 |  0.7 |      1.3
   4 |    5 |    4 |  0.3 |      1.6
   5 |    1 |    1 |    1 |      1.6
   6 |    6 |    8 |    1 |      2.6
   7 |    8 |    7 |    1 |      2.6
   8 |   10 |   10 |    1 |      2.6
   9 |   -3 |   12 |  0.6 |      3.2
  10 |   -4 |    6 |  0.7 |      3.3
  11 |    7 |    6 |  0.3 |      3.6
  12 |    9 |    9 |    1 |      3.6
  13 |   11 |   11 |    1 |      3.6
  14 |   13 |   14 |    1 |      3.6
(14 rows)

Example

From point \(1\) with \(agg\_cost <= 3.8\), does not matter driving side, with details

SELECT * FROM pgr_withPointsDD(
    'SELECT id, source, target, cost, reverse_cost FROM edge_table ORDER BY id',
    'SELECT pid, edge_id, fraction, side from pointsOfInterest',
    -1, 3.8,
    driving_side := 'b',
    details := true);
 seq | node | edge | cost | agg_cost
-----+------+------+------+----------
   1 |   -1 |   -1 |    0 |        0
   2 |    1 |    1 |  0.4 |      0.4
   3 |    2 |    1 |  0.6 |      0.6
   4 |   -6 |    4 |  0.7 |      1.3
   5 |    5 |    4 |  0.3 |      1.6
   6 |    6 |    8 |    1 |      2.6
   7 |    8 |    7 |    1 |      2.6
   8 |   10 |   10 |    1 |      2.6
   9 |   -3 |   12 |  0.6 |      3.2
  10 |   -4 |    6 |  0.7 |      3.3
  11 |    7 |    6 |  0.3 |      3.6
  12 |    9 |    9 |    1 |      3.6
  13 |   11 |   11 |    1 |      3.6
  14 |   13 |   14 |    1 |      3.6
(14 rows)

The queries use the Sample Data network.

See Also

Indices and tables