pgr_bdAstar¶
Name¶
pgr_bdAstar
— Returns the shortest path using A* algorithm.
Availability:
- pgr_bdAstar(one to one) 2.0.0, Signature change on 2.5.0
- pgr_bdAstar(other signatures) 2.5.0
Signature Summary¶
pgr_bdAstar(edges_sql, start_vid, end_vid)
pgr_bdAstar(edges_sql, start_vid, end_vid, directed [, heuristic, factor, epsilon])
RETURNS SET OF (seq, path_seq , node, edge, cost, agg_cost)
OR EMPTY SET
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
pgr_bdAstar(edges_sql, start_vid, end_vids [, directed, heuristic, factor, epsilon])
pgr_bdAstar(edges_sql, start_vids, end_vid [, directed, heuristic, factor, epsilon])
pgr_bdAstar(edges_sql, start_vids, end_vids [, directed, heuristic, factor, epsilon])
RETURNS SET OF (seq, path_seq [, start_vid] [, end_vid], node, edge, cost, agg_cost)
OR EMPTY SET
Using these signatures, will load once the graph and perform several one to one pgr_bdAstar
- The result is the union of the results of the one to one pgr_bdAStar.
- The extra
start_vid
and/orend_vid
in the result is used to distinguish to which path it belongs.
Avaliability
- pgr_bdAstar(one to one) 2.0, signature change on 2.5
- pgr_bdAstar(other signatures) 2.5
Signatures¶
Minimal Signature¶
pgr_bdAstar(edges_sql, start_vid, end_vid)
RETURNS SET OF (seq, path_seq, node, edge, cost, agg_cost)
- This usage finds the shortest path from the
start_vid
to theend_vid
- on a directed graph
- with heuristic’s value 5
- with factor’s value 1
- with epsilon’s value 1
Example: | Using the defaults |
---|
SELECT * FROM pgr_bdAstar(
'SELECT id, source, target, cost, reverse_cost, x1,y1,x2,y2
FROM edge_table',
2, 3
);
seq | path_seq | node | edge | cost | agg_cost
-----+----------+------+------+------+----------
1 | 1 | 2 | 4 | 1 | 0
2 | 2 | 5 | 8 | 1 | 3
3 | 3 | 6 | 9 | 1 | 5
4 | 4 | 9 | 16 | 1 | 8
5 | 5 | 4 | 3 | 1 | 9
6 | 6 | 3 | -1 | 0 | 10
(6 rows)
pgr_bdAstar One to One¶
pgr_bdAstar(edges_sql, start_vid, end_vid, directed [, heuristic, factor, epsilon])
RETURNS SET OF (seq, path_seq, node, edge, cost, agg_cost)
- This usage finds the shortest path from the
start_vid
to theend_vid
allowing the user to choose - heuristic,
- and/or factor
- and/or epsilon.
Note
In the One to One signature, because of the deprecated signature existence, it is compulsory to indicate if the graph is directed or undirected.
Example: | Directed using Heuristic 2 |
---|
SELECT * FROM pgr_bdAstar(
'SELECT id, source, target, cost, reverse_cost, x1,y1,x2,y2
FROM edge_table',
2, 3,
true, heuristic := 2
);
seq | path_seq | node | edge | cost | agg_cost
-----+----------+------+------+------+----------
1 | 1 | 2 | 4 | 1 | 0
2 | 2 | 5 | 8 | 1 | 2
3 | 3 | 6 | 9 | 1 | 3
4 | 4 | 9 | 16 | 1 | 4
5 | 5 | 4 | 3 | 1 | 5
6 | 6 | 3 | -1 | 0 | 6
(6 rows)
pgr_bdAstar One to many¶
pgr_bdAstar(edges_sql, start_vid, end_vids [, directed, heuristic, factor, epsilon])
RETURNS SET OF (seq, path_seq, end_vid, node, edge, cost, agg_cost) or EMPTY SET
- This usage finds the shortest path from the
start_vid
to eachend_vid
inend_vids
allowing the user to choose - if the graph is directed or undirected
- and/or heuristic,
- and/or factor
- and/or epsilon.
Example: | Directed using Heuristic 3 and a factor of 3.5 |
---|
SELECT * FROM pgr_bdAstar(
'SELECT id, source, target, cost, reverse_cost, x1,y1,x2,y2
FROM edge_table',
2, ARRAY[3, 11],
heuristic := 3, factor := 3.5
);
seq | path_seq | end_vid | node | edge | cost | agg_cost
-----+----------+---------+------+------+------+----------
1 | 1 | 3 | 2 | 4 | 1 | 0
2 | 2 | 3 | 5 | 8 | 1 | 25.5
3 | 3 | 3 | 6 | 9 | 1 | 38.75
4 | 4 | 3 | 9 | 16 | 1 | 64.25
5 | 5 | 3 | 4 | 3 | 1 | 65.25
6 | 6 | 3 | 3 | -1 | 0 | 66.25
7 | 1 | 11 | 2 | 4 | 1 | 0
8 | 2 | 11 | 5 | 8 | 1 | 1
9 | 3 | 11 | 6 | 11 | 1 | 2
10 | 4 | 11 | 11 | -1 | 0 | 3
(10 rows)
pgr_bdAstar Many to One¶
pgr_bdAstar(edges_sql, start_vids, end_vid [, directed, heuristic, factor, epsilon])
RETURNS SET OF (seq, path_seq, start_vid, node, edge, cost, agg_cost) or EMPTY SET
- This usage finds the shortest path from each
start_vid
instart_vids
to theend_vid
allowing the user to choose - if the graph is directed or undirected
- and/or heuristic,
- and/or factor
- and/or epsilon.
Example: | Undirected graph with Heuristic 4 |
---|
SELECT * FROM pgr_bdAstar(
'SELECT id, source, target, cost, reverse_cost, x1,y1,x2,y2
FROM edge_table',
ARRAY[2, 7], 3,
false, heuristic := 4
);
seq | path_seq | start_vid | node | edge | cost | agg_cost
-----+----------+-----------+------+------+------+------------------
1 | 1 | 2 | 2 | 2 | 1 | 0
2 | 2 | 2 | 3 | -1 | 0 | 1
3 | 1 | 7 | 7 | 6 | 1 | 0
4 | 2 | 7 | 8 | 7 | 1 | 3.23606797749979
5 | 3 | 7 | 5 | 8 | 1 | 5.65028153987288
6 | 4 | 7 | 6 | 5 | 1 | 6.65028153987288
7 | 5 | 7 | 3 | -1 | 0 | 7.65028153987288
(7 rows)
pgr_bdAstar Many to Many¶
pgr_bdAstar(edges_sql, start_vids, end_vids [, directed, heuristic, factor, epsilon])
RETURNS SET OF (seq, path_seq, start_vid, end_vid, node, edge, cost, agg_cost) or EMPTY SET
- This usage finds the shortest path from each
start_vid
instart_vids
to eachend_vid
inend_vids
allowing the user to choose - if the graph is directed or undirected
- and/or heuristic,
- and/or factor
- and/or epsilon.
Example: | Directed graph with a factor of 0.5 |
---|
SELECT * FROM pgr_bdAstar(
'SELECT id, source, target, cost, reverse_cost, x1,y1,x2,y2
FROM edge_table',
ARRAY[2, 7], ARRAY[3, 11],
factor := 0.5
);
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 | 2
3 | 3 | 2 | 3 | 6 | 9 | 1 | 3.5
4 | 4 | 2 | 3 | 9 | 16 | 1 | 4.5
5 | 5 | 2 | 3 | 4 | 3 | 1 | 5.5
6 | 6 | 2 | 3 | 3 | -1 | 0 | 6.5
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 | 2.5
13 | 3 | 7 | 3 | 5 | 8 | 1 | 4.5
14 | 4 | 7 | 3 | 6 | 9 | 1 | 6
15 | 5 | 7 | 3 | 9 | 16 | 1 | 7
16 | 6 | 7 | 3 | 4 | 3 | 1 | 8
17 | 7 | 7 | 3 | 3 | -1 | 0 | 9
18 | 1 | 7 | 11 | 7 | 6 | 1 | 0
19 | 2 | 7 | 11 | 8 | 7 | 1 | 1
20 | 3 | 7 | 11 | 5 | 8 | 1 | 2
21 | 4 | 7 | 11 | 6 | 11 | 1 | 3
22 | 5 | 7 | 11 | 11 | -1 | 0 | 4
(22 rows)
Description of the Signatures¶
Description of the edges_sql query for astar 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),
|
x1 | ANY-NUMERICAL |
X coordinate of source vertex. | |
y1 | ANY-NUMERICAL |
Y coordinate of source vertex. | |
x2 | ANY-NUMERICAL |
X coordinate of target vertex. | |
y2 | ANY-NUMERICAL |
Y coordinate of target vertex. |
Where:
ANY-INTEGER: | SMALLINT, INTEGER, BIGINT |
---|---|
ANY-NUMERICAL: | SMALLINT, INTEGER, BIGINT, REAL, FLOAT |
Description of the parameters of the signatures¶
Parameter | Type | Description |
---|---|---|
edges_sql | TEXT |
Edges SQL query as described above. |
start_vid | ANY-INTEGER |
Starting vertex identifier. |
start_vids | ARRAY[ANY-INTEGER] |
Starting vertices identifierers. |
end_vid | ANY-INTEGER |
Ending vertex identifier. |
end_vids | ARRAY[ANY-INTEGER] |
Ending vertices identifiers. |
directed | BOOLEAN |
|
heuristic | INTEGER |
(optional). Heuristic number. Current valid values 0~5. Default
|
factor | FLOAT |
(optional). For units manipulation. \(factor > 0\). Default 1 . see Factor |
epsilon | FLOAT |
(optional). For less restricted results. \(epsilon >= 1\). Default 1 . |
Description of the return values for a path¶
Returns set of (seq, path_seq [, start_vid] [, end_vid], node, edge, cost, agg_cost)
Column | Type | Description |
---|---|---|
seq | INT |
Sequential value starting from 1. |
path_id | INT |
Path identifier. Has value 1 for the first of a path. Used when there are multiple paths for the same start_vid to end_vid combination. |
path_seq | INT |
Relative position in the path. Has value 1 for the beginning of a path. |
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. |
node | BIGINT |
Identifier of the node in the path from start_vid to end_vid . |
edge | BIGINT |
Identifier of the edge used to go from node to the next node in the path sequence. -1 for the last node of the path. |
cost | FLOAT |
Cost to traverse from node using edge to the next node in the path sequence. |
agg_cost | FLOAT |
Aggregate cost from start_v to node . |
See Also¶
- Bidirectional A* - Family of functions
- Sample Data network.
- http://www.boost.org/libs/graph/doc/astar_search.html
- http://en.wikipedia.org/wiki/A*_search_algorithm
Indices and tables