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pgr_dijkstraCostMatrix - pgRouting Manual (3.0)

pgr_dijkstraCostMatrix

pgr_dijkstraCostMatrix - Calculates the a cost matrix using pgr_dijktras.

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Availability

Version 3.0.0
- Official function
Version 2.3.0
- New proposed function
Supported versions: current( 3.0 )
Unsupported versions: 2.6 2.5 2.4 2.3

Description

Using Dijkstra algorithm, calculate and return a cost matrix.

Signatures

Summary

     pgr_dijkstraCostMatrix(edges_sql, start_vids [, directed])
RETURNS SET OF (start_vid, end_vid, agg_cost)

Using defaults

     pgr_dijkstraCostMatrix(edges_sql, start_vid)
RETURNS SET OF (start_vid, end_vid, agg_cost)

Example :: Cost matrix for vertices \(\{1, 2, 3, 4\}\) on a directed graph

     SELECT * FROM pgr_dijkstraCostMatrix(
    'SELECT id, source, target, cost, reverse_cost FROM edge_table',
    (SELECT array_agg(id) FROM edge_table_vertices_pgr WHERE id < 5)
);
 start_vid  end_vid  agg_cost
-----------+---------+----------
         1        2         1
         1        3         6
         1        4         5
         2        1         1
         2        3         5
         2        4         4
         3        1         2
         3        2         1
         3        4         3
         4        1         3
         4        2         2
         4        3         1
(12 rows)


    

Complete Signature

      pgr_dijkstraCostMatrix(edges_sql, start_vids [, directed])
RETURNS SET OF (start_vid, end_vid, agg_cost)

Example :: Symmetric cost matrix for vertices \(\{1, 2, 3, 4\}\) on an undirected graph

      SELECT * FROM pgr_dijkstraCostMatrix(
    'SELECT id, source, target, cost, reverse_cost FROM edge_table',
    (SELECT array_agg(id) FROM edge_table_vertices_pgr WHERE id < 5),
    false
);
 start_vid  end_vid  agg_cost
-----------+---------+----------
         1        2         1
         1        3         2
         1        4         3
         2        1         1
         2        3         1
         2        4         2
         3        1         2
         3        2         1
         3        4         1
         4        1         3
         4        2         2
         4        3         1
(12 rows)


     

Parameters

Parameter	Type	Description
edges_sql	`TEXT`	Edges SQL query as described above.
start_vids	`ARRAY[ANY-INTEGER]`	Array of identifiers of the vertices.
directed	`BOOLEAN`	(optional). When `false` the graph is considered as Undirected. Default is `true` which considers the graph as Directed.

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

Return Columns

Returns SET OF (start_vid, end_vid, agg_cost)

Column	Type	Description
start_vid	`BIGINT`	Identifier of the starting vertex. Used when multiple starting vetrices are in the query.
end_vid	`BIGINT`	Identifier of the ending vertex. Used when multiple ending vertices are in the query.
agg_cost	`FLOAT`	Aggregate cost from `start_vid` to `end_vid` .

Additional Examples

Example :: Use with tsp

     SELECT * FROM pgr_TSP(
    $$
    SELECT * FROM pgr_dijkstraCostMatrix(
        'SELECT id, source, target, cost, reverse_cost FROM edge_table',
        (SELECT array_agg(id) FROM edge_table_vertices_pgr WHERE id < 5),
        false
    )
    $$,
    randomize := false
);
 seq  node  cost  agg_cost
-----+------+------+----------
   1     1     1         0
   2     2     1         1
   3     3     1         2
   4     4     3         3
   5     1     0         6
(5 rows)


    