pgr_aStarCost – proposed¶
Name¶
pgr_aStarCost
— Returns the aggregate cost shortest path using aStar - Family of functions algorithm.
Availability: 2.4.0
Signature Summary¶
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.
pgr_aStarCost(edges_sql, start_vid, end_vid) -- Proposed
pgr_aStarCost(edges_sql, start_vid, end_vid, directed, heuristic, factor, epsilon) -- Proposed
pgr_aStarCost(edges_sql, start_vid, end_vids, directed, heuristic, factor, epsilon) -- Proposed
pgr_aStarCost(edges_sql, starts_vid, end_vid, directed, heuristic, factor, epsilon) -- Proposed
pgr_aStarCost(edges_sql, starts_vid, end_vids, directed, heuristic, factor, epsilon) -- Proposed
RETURNS SET OF (start_vid, end_vid, agg_cost) OR EMPTY SET
Signatures¶
Minimal Signature¶
pgr_aStarCost(edges_sql, start_vid, end_vid)
RETURNS SET OF (start_vid, end_vid, agg_cost) OR EMPTY SET
Example: | Using the defaults |
---|
SELECT * FROM pgr_aStarCost(
'SELECT id, source, target, cost, reverse_cost, x1, y1, x2, y2 FROM edge_table',
2, 12);
start_vid | end_vid | agg_cost
-----------+---------+----------
2 | 12 | 4
(1 row)
One to One¶
pgr_aStarCost(edges_sql, start_vid, end_vid, directed, heuristic, factor, epsilon)
RETURNS SET OF (start_vid, end_vid, agg_cost) OR EMPTY SET
Example: | Setting a Heuristic |
---|
SELECT * FROM pgr_aStarCost(
'SELECT id, source, target, cost, reverse_cost, x1, y1, x2, y2 FROM edge_table',
2, 12,
directed := false, heuristic := 2);
start_vid | end_vid | agg_cost
-----------+---------+----------
2 | 12 | 4
(1 row)
One to many¶
pgr_aStarCost(edges_sql, start_vid, end_vids, directed, heuristic, factor, epsilon) -- Proposed
RETURNS SET OF (start_vid, end_vid, agg_cost) OR EMPTY SET
- This signature finds a 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_astar
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_astar.
- The extra
end_vid
column in the result is used to distinguish to which path it belongs.
Example: |
---|
SELECT * FROM pgr_aStarCost(
'SELECT id, source, target, cost, reverse_cost, x1, y1, x2, y2 FROM edge_table',
2, ARRAY[3, 12], heuristic := 2);
start_vid | end_vid | agg_cost
-----------+---------+----------
2 | 3 | 5
2 | 12 | 4
(2 rows)
Many to One¶
pgr_aStarCost(edges_sql, starts_vid, end_vid, directed, heuristic, factor, epsilon) -- Proposed
RETURNS SET OF (start_vid, end_vid, 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_aStar where the ending vertex is fixed.
- The result is the union of the results of the one to one pgr_aStar.
- The extra
start_vid
column in the result is used to distinguish to which path it belongs.
Example: |
---|
SELECT * FROM pgr_aStarCost(
'SELECT id, source, target, cost, reverse_cost, x1, y1, x2, y2 FROM edge_table',
ARRAY[7, 2], 12, heuristic := 0);
start_vid | end_vid | agg_cost
-----------+---------+----------
2 | 12 | 4
7 | 12 | 5
(2 rows)
Many to Many¶
pgr_aStarCost(edges_sql, starts_vid, end_vids, directed, heuristic, factor, epsilon) -- Proposed
RETURNS SET OF (start_vid, end_vid, 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_aStarCost(
'SELECT id, source, target, cost, reverse_cost, x1, y1, x2, y2 FROM edge_table',
ARRAY[7, 2], ARRAY[3, 12], heuristic := 2);
start_vid | end_vid | agg_cost
-----------+---------+----------
2 | 3 | 5
2 | 12 | 4
7 | 3 | 6
7 | 12 | 5
(4 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. |
end_vid | ANY-INTEGER |
Ending vertex identifier. |
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 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¶
- aStar - 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