pgr_dijkstraCost
Using Dijkstra algorithm implemented by Boost.Graph, and extract only the aggregate cost of the shortest path(s) found, for the combination of vertices given.
Availability
The pgr_dijkstraCost
algorithm, is a good choice to calculate the sum of the costs
of the shortest path for a subset of pairs of nodes of the graph.
We make use of the Boost’s implementation of dijkstra which runs in
\(O(V \log V + E)\) time.
pgr_dijkstraCost(edges_sql, start_vid, end_vid);
pgr_dijkstraCost(edges_sql, start_vid, end_vid, directed);
pgr_dijkstraCost(edges_sql, start_vids, end_vid, directed);
pgr_dijkstraCost(edges_sql, start_vid, end_vids, directed);
pgr_dijkstraCost(edges_sql, start_vids, end_vids, directed);
RETURNS SET OF (start_vid, end_vid, agg_cost) or EMPTY SET
The minimal signature is for a directed graph from one start_vid
to one end_vid
:
pgr_dijkstraCost(TEXT edges_sql, BIGINT start_vid, BIGINT end_vid)
RETURNS SET OF (start_vid, end_vid, agg_cost) or EMPTY SET
Example
SELECT * FROM pgr_dijkstraCost(
'select id, source, target, cost, reverse_cost from edge_table',
2, 3);
start_vid | end_vid | agg_cost
-----------+---------+----------
2 | 3 | 5
(1 row)
start_vid
to one end_vid
:directed
flag is missing or is set to true
.directed
flag is set to false
.pgr_dijkstraCost(TEXT edges_sql, BIGINT start_vid, BIGINT end_vid,
BOOLEAN directed:=true);
RETURNS SET OF (start_vid, end_vid, agg_cost) or EMPTY SET
Example: |
---|
SELECT * FROM pgr_dijkstraCost(
'select id, source, target, cost, reverse_cost from edge_table',
2, 3, false);
start_vid | end_vid | agg_cost
-----------+---------+----------
2 | 3 | 1
(1 row)
pgr_dijkstraCost(TEXT edges_sql, BIGINT start_vid, array[ANY_INTEGER] end_vids,
BOOLEAN directed:=true);
RETURNS SET OF (start_vid, end_vid, agg_cost) or EMPTY SET
start_vid
to each end_vid
in end_vids
:directed
flag is missing or is set to true
.directed
flag is set to false
.Example: |
---|
SELECT * FROM pgr_dijkstraCost(
'select id, source, target, cost, reverse_cost from edge_table',
2, ARRAY[3, 11]);
start_vid | end_vid | agg_cost
-----------+---------+----------
2 | 3 | 5
2 | 11 | 3
(2 rows)
pgr_dijkstraCost(TEXT edges_sql, array[ANY_INTEGER] start_vids, BIGINT end_vid,
BOOLEAN directed:=true);
RETURNS SET OF (start_vid, end_vid, agg_cost) or EMPTY SET
start_vid
in start_vids
to one end_vid
:directed
flag is missing or is set to true
.directed
flag is set to false
.Example: |
---|
SELECT * FROM pgr_dijkstraCost(
'select id, source, target, cost, reverse_cost from edge_table',
ARRAY[2, 7], 3);
start_vid | end_vid | agg_cost
-----------+---------+----------
2 | 3 | 5
7 | 3 | 6
(2 rows)
pgr_dijkstraCost(TEXT edges_sql, array[ANY_INTEGER] start_vids, array[ANY_INTEGER] end_vids,
BOOLEAN directed:=true);
RETURNS SET OF (start_vid, end_vid, agg_cost) or EMPTY SET
start_vid
in start_vids
to each end_vid
in end_vids
:directed
flag is missing or is set to true
.directed
flag is set to false
.Example: |
---|
SELECT * FROM pgr_dijkstraCost(
'select id, source, target, cost, reverse_cost from edge_table',
ARRAY[2, 7], ARRAY[3, 11]);
start_vid | end_vid | agg_cost
-----------+---------+----------
2 | 3 | 5
2 | 11 | 3
7 | 3 | 6
7 | 11 | 4
(4 rows)
edges_sql: | an SQL query, which should return a set of rows with the following columns: |
---|
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)
|
|
reverse_cost | ANY-NUMERICAL |
-1 | Weight of the edge (target, source),
|
Where:
ANY-INTEGER: | SMALLINT, INTEGER, BIGINT |
---|---|
ANY-NUMERICAL: | SMALLINT, INTEGER, BIGINT, REAL, FLOAT |
Column | Type | Default | Description |
---|---|---|---|
sql | TEXT |
SQL query as described above. | |
start_vid | BIGINT |
Identifier of the starting vertex of the path. | |
start_vids | ARRAY[BIGINT] |
Array of identifiers of starting vertices. | |
end_vid | BIGINT |
Identifier of the ending vertex of the path. | |
end_vids | ARRAY[BIGINT] |
Array of identifiers of ending vertices. | |
directed | BOOLEAN |
true |
|
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 . |
Example 1: | Demonstration of repeated values are ignored, and result is sorted. |
---|
SELECT * FROM pgr_dijkstraCost(
'select id, source, target, cost, reverse_cost from edge_table',
ARRAY[5, 3, 4, 3, 3, 4], ARRAY[3, 5, 3, 4]);
start_vid | end_vid | agg_cost
-----------+---------+----------
3 | 4 | 3
3 | 5 | 2
4 | 3 | 1
4 | 5 | 3
5 | 3 | 4
5 | 4 | 3
(6 rows)
Example 2: | Making start_vids the same as end_vids |
---|
SELECT * FROM pgr_dijkstraCost(
'select id, source, target, cost, reverse_cost from edge_table',
ARRAY[5, 3, 4], ARRAY[5, 3, 4]);
start_vid | end_vid | agg_cost
-----------+---------+----------
3 | 4 | 3
3 | 5 | 2
4 | 3 | 1
4 | 5 | 3
5 | 3 | 4
5 | 4 | 3
(6 rows)
Indices and tables