pgr_bdDijkstraCost - Proposed¶
pgr_bdDijkstraCost
— Returns the shortest path(s)’s cost using Bidirectional Dijkstra algorithm.
Availability: 2.5.0
Warning
Experimental functions
- They are not officially of the current release.
- They likely will not be officially be part of the next release:
- The functions might not make use of ANY-INTEGER and ANY-NUMERICAL
- Name might change.
- Signature might change.
- Functionality might change.
- pgTap tests might be missing.
- Might need c/c++ coding.
- May lack documentation.
- Documentation if any might need to be rewritten.
- Documentation examples might need to be automatically generated.
- Might need a lot of feedback from the comunity.
- Might depend on a proposed function of pgRouting
- Might depend on a deprecated function of pgRouting
Signature Summary¶
pgr_dijkstraCost(edges_sql, start_vid, end_vid)
pgr_bdDijkstraCost(edges_sql, start_vid, end_vid, directed)
pgr_bdDijkstraCost(edges_sql, start_vid, end_vids, directed)
pgr_bdDijkstraCost(edges_sql, start_vids, end_vid, directed)
pgr_bdDijkstraCost(edges_sql, start_vids, end_vids, directed)
RETURNS SET OF (start_vid, end_vid, agg_cost)
OR EMPTY SET
Signatures¶
Minimal signature¶
pgr_bdDijkstraCost(edges_sql, start_vid, end_vid)
RETURNS SET OF (seq, path_seq, node, edge, cost, agg_cost) or EMPTY SET
The minimal signature is for a directed graph from one start_vid
to one end_vid
:
Example: |
---|
SELECT * FROM pgr_bdDijkstraCost(
'SELECT id, source, target, cost, reverse_cost FROM edge_table',
2, 3
);
start_vid | end_vid | agg_cost
-----------+---------+----------
2 | 3 | 5
(1 row)
pgr_bdDijkstraCost One to One¶
pgr_bdDijkstraCost(edges_sql, start_vid, end_vid, directed)
RETURNS SET OF (seq, path_seq, node, edge, cost, agg_cost) or EMPTY SET
- This signature finds the shortest path from one
start_vid
to oneend_vid
: - on a directed graph when
directed
flag is missing or is set totrue
. - on an undirected graph when
directed
flag is set tofalse
.
- on a directed graph when
Example: |
---|
SELECT * FROM pgr_bdDijkstra(
'SELECT id, source, target, cost, reverse_cost FROM edge_table',
2, 3,
false
);
seq | path_seq | node | edge | cost | agg_cost
-----+----------+------+------+------+----------
1 | 1 | 2 | 2 | 1 | 0
2 | 2 | 3 | -1 | 0 | 1
(2 rows)
pgr_bdDijkstraCost One to many¶
pgr_bdDijkstra(edges_sql, start_vid, end_vids, directed)
RETURNS SET OF (seq, path_seq, end_vid, node, edge, cost, agg_cost) or EMPTY SET
- This signature finds the shortest path from one
start_vid
to eachend_vid
inend_vids
: - on a directed graph when
directed
flag is missing or is set totrue
. - on an undirected graph when
directed
flag is set tofalse
.
- on a directed graph when
Using this signature, will load once the graph and perform a one to one pgr_dijkstra
where the starting vertex is fixed, and stop when all end_vids
are reached.
- The result is equivalent to the union of the results of the one to one pgr_dijkstra.
- The extra
end_vid
in the result is used to distinguish to which path it belongs.
Example: |
---|
SELECT * FROM pgr_bdDijkstraCost(
'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_bdDijkstraCost Many to One¶
pgr_bdDijkstra(edges_sql, start_vids, end_vid, directed)
RETURNS SET OF (seq, path_seq, start_vid, node, edge, cost, agg_cost) or EMPTY SET
- This signature finds the shortest path from each
start_vid
instart_vids
to oneend_vid
: - on a directed graph when
directed
flag is missing or is set totrue
. - on an undirected graph when
directed
flag is set tofalse
.
- on a directed graph when
Using this signature, will load once the graph and perform several one to one pgr_dijkstra where the ending vertex is fixed.
- The result is the union of the results of the one to one pgr_dijkstra.
- The extra
start_vid
in the result is used to distinguish to which path it belongs.
Example: |
---|
SELECT * FROM pgr_bdDijkstra(
'SELECT id, source, target, cost, reverse_cost FROM edge_table',
ARRAY[2, 7], 3);
seq | path_seq | start_vid | node | edge | cost | agg_cost
-----+----------+-----------+------+------+------+----------
1 | 1 | 2 | 2 | 4 | 1 | 0
2 | 2 | 2 | 5 | 8 | 1 | 1
3 | 3 | 2 | 6 | 9 | 1 | 2
4 | 4 | 2 | 9 | 16 | 1 | 3
5 | 5 | 2 | 4 | 3 | 1 | 4
6 | 6 | 2 | 3 | -1 | 0 | 5
7 | 1 | 7 | 7 | 6 | 1 | 0
8 | 2 | 7 | 8 | 7 | 1 | 1
9 | 3 | 7 | 5 | 8 | 1 | 2
10 | 4 | 7 | 6 | 9 | 1 | 3
11 | 5 | 7 | 9 | 16 | 1 | 4
12 | 6 | 7 | 4 | 3 | 1 | 5
13 | 7 | 7 | 3 | -1 | 0 | 6
(13 rows)
pgr_bdDijkstraCost Many to Many¶
pgr_bdDijkstra(edges_sql, start_vids, end_vids, directed)
RETURNS SET OF (seq, path_seq, start_vid, end_vid, node, edge, cost, agg_cost) or EMPTY SET
- This signature finds the shortest path from each
start_vid
instart_vids
to eachend_vid
inend_vids
: - on a directed graph when
directed
flag is missing or is set totrue
. - on an undirected graph when
directed
flag is set tofalse
.
- on a directed graph when
Using this signature, will load once the graph and perform several one to Many pgr_dijkstra
for all start_vids
.
- The result is the union of the results of the one to one pgr_dijkstra.
- The extra
start_vid
in the result is used to distinguish to which path it belongs.
The extra start_vid
and end_vid
in the result is used to distinguish to which path it belongs.
Example: |
---|
SELECT * FROM pgr_bdDijkstra(
'SELECT id, source, target, cost, reverse_cost FROM edge_table',
ARRAY[2, 7], ARRAY[3, 11]);
seq | path_seq | start_vid | end_vid | node | edge | cost | agg_cost
-----+----------+-----------+---------+------+------+------+----------
1 | 1 | 2 | 3 | 2 | 4 | 1 | 0
2 | 2 | 2 | 3 | 5 | 8 | 1 | 1
3 | 3 | 2 | 3 | 6 | 9 | 1 | 2
4 | 4 | 2 | 3 | 9 | 16 | 1 | 3
5 | 5 | 2 | 3 | 4 | 3 | 1 | 4
6 | 6 | 2 | 3 | 3 | -1 | 0 | 5
7 | 1 | 2 | 11 | 2 | 4 | 1 | 0
8 | 2 | 2 | 11 | 5 | 8 | 1 | 1
9 | 3 | 2 | 11 | 6 | 11 | 1 | 2
10 | 4 | 2 | 11 | 11 | -1 | 0 | 3
11 | 1 | 7 | 3 | 7 | 6 | 1 | 0
12 | 2 | 7 | 3 | 8 | 7 | 1 | 1
13 | 3 | 7 | 3 | 5 | 8 | 1 | 2
14 | 4 | 7 | 3 | 6 | 9 | 1 | 3
15 | 5 | 7 | 3 | 9 | 16 | 1 | 4
16 | 6 | 7 | 3 | 4 | 3 | 1 | 5
17 | 7 | 7 | 3 | 3 | -1 | 0 | 6
18 | 1 | 7 | 11 | 7 | 6 | 1 | 0
19 | 2 | 7 | 11 | 8 | 7 | 1 | 1
20 | 3 | 7 | 11 | 5 | 10 | 1 | 2
21 | 4 | 7 | 11 | 10 | 12 | 1 | 3
22 | 5 | 7 | 11 | 11 | -1 | 0 | 4
(22 rows)
Description of the Signatures¶
Description of the edges_sql query for dijkstra like functions¶
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 |
Description of the parameters of the signatures¶
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 |
|
Description of the return values for a Cost function¶
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 . |
See Also¶
- The queries use the Sample Data network.
- pgr_bdDijkstra
- http://www.cs.princeton.edu/courses/archive/spr06/cos423/Handouts/EPP%20shortest%20path%20algorithms.pdf
- https://en.wikipedia.org/wiki/Bidirectional_search
Indices and tables