pgr_aStarCost¶
pgr_aStarCost
— Returns the aggregate cost shortest path using pgr_aStar algorithm.
Availability
- Version 3.2.0
- New proposed function:
- pgr_aStarCost(Combinations)
- New proposed function:
- Version 3.0.0
- Official function
- Version 2.4.0
- New proposed function
Description¶
The main characteristics are:
- Default kind of graph is directed when
directed
flag is missing.directed
flag is set to true
- Unless specified otherwise, ordering is:
- first by
start_vid
(if exists) - then by
end_vid
- first by
- Values are returned when there is a path
- Let \(v\) and \(u\) be nodes on the graph:
- If there is no path from \(v\) to \(u\):
- no corresponding row is returned
agg_cost
from \(v\) to \(u\) is \(\infty\)
- There is no path when \(v = u\) therefore
- no corresponding row is returned
agg_cost
from v to u is \(0\)
- If there is no path from \(v\) to \(u\):
- Edges with negative costs are not included in the graph.
- When (x,y) coordinates for the same vertex identifier differ:
- A random selection of the vertex’s (x,y) coordinates is used.
- Running time: \(O((E + V) * \log V)\)
- The results are equivalent to the union of the results of the pgr_aStarCost( One to One ) on the:
- pgr_aStarCost( One to Many )
- pgr_aStarCost( Many to One )
- pgr_aStarCost( Many to Many )
Signatures¶
Summary
pgr_aStarCost(Edges SQL, from_vid, to_vid [, directed] [, heuristic] [, factor] [, epsilon])
pgr_aStarCost(Edges SQL, from_vid, to_vids [, directed] [, heuristic] [, factor] [, epsilon])
pgr_aStarCost(Edges SQL, from_vids, to_vid [, directed] [, heuristic] [, factor] [, epsilon])
pgr_aStarCost(Edges SQL, from_vids, to_vids [, directed] [, heuristic] [, factor] [, epsilon])
pgr_aStarCost(Edges SQL, Combinations SQL [, directed] [, heuristic] [, factor] [, epsilon])
RETURNS SET OF (start_vid, end_vid, agg_cost)
OR EMPTY SET
Optional parameters are named parameters and have a default value.
Using defaults
pgr_aStarCost(Edges SQL, start_vid, end_vid)
RETURNS SET OF (start_vid, end_vid, agg_cost)
OR EMPTY SET
Example: | From vertex \(2\) to vertex \(12\) on a directed graph |
---|
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, from_vid, to_vid [, directed] [, heuristic] [, factor] [, epsilon])
RETURNS SET OF (start_vid, end_vid, agg_cost)
OR EMPTY SET
Example: | From vertex \(2\) to vertex \(12\) on an undirected graph using heuristic \(2\) |
---|
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, from_vid, to_vids [, directed] [, heuristic] [, factor] [, epsilon])
RETURNS SET OF (start_vid, end_vid, agg_cost)
OR EMPTY SET
Example: | From vertex \(2\) to vertices \(\{3, 12\}\) on a directed graph using heuristic \(2\) |
---|
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, from_vids, to_vid [, directed] [, heuristic] [, factor] [, epsilon])
RETURNS SET OF (start_vid, end_vid, agg_cost)
OR EMPTY SET
Example: | From vertices \(\{7, 2\}\) to vertex \(12\) on a directed graph using heuristic \(0\) |
---|
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, from_vids, to_vids [, directed] [, heuristic] [, factor] [, epsilon])
RETURNS SET OF (start_vid, end_vid, agg_cost)
OR EMPTY SET
Example: | From vertices \(\{7, 2\}\) to vertices \(\{3, 12\}\) on a directed graph using heuristic \(2\) |
---|
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)
Combinations¶
pgr_aStarCost(Edges SQL, Combinations SQL [, directed] [, heuristic] [, factor] [, epsilon])
RETURNS SET OF (start_vid, end_vid, agg_cost)
OR EMPTY SET
Example: | Using a combinations table on a directed graph using heuristic \(2\). |
---|
SELECT * FROM pgr_aStarCost(
'SELECT id, source, target, cost, reverse_cost, x1, y1, x2, y2 FROM edge_table',
'SELECT * FROM ( VALUES (7, 3), (2, 12) ) AS t(source, target)',
heuristic := 2);
start_vid | end_vid | agg_cost
-----------+---------+----------
2 | 12 | 4
7 | 3 | 6
(2 rows)
Parameters¶
Parameter | Type | Description |
---|---|---|
Edges SQL | TEXT |
Edges query as described below. |
Combinations SQL | TEXT |
Combinations query as described below. |
from_vid | ANY-INTEGER |
Starting vertex identifier. Parameter in: |
from_vids | ARRAY[ANY-INTEGER] |
Array of starting vertices identifiers. Parameter in: |
to_vid | ANY-INTEGER |
Ending vertex identifier. Parameter in: |
to_vids | ARRAY[ANY-INTEGER] |
Array of ending vertices identifiers. Parameter in: |
Optional Parameters¶
Parameter | Type | Default | Description |
---|---|---|---|
directed | BOOLEAN |
true |
|
heuristic | INTEGER |
5 |
Heuristic number. Current valid values 0~5. Default
|
factor | FLOAT |
1 |
For units manipulation. \(factor > 0\). See Factor |
epsilon | FLOAT |
1 |
For less restricted results. \(epsilon >= 1\). |
Inner queries¶
Edges query¶
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 |
Combinations query¶
Column | Type | Default | Description |
---|---|---|---|
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. |
Where:
ANY-INTEGER: | SMALLINT, INTEGER, BIGINT |
---|
Result Columns¶
Returns SET OF (start_vid, end_vid, agg_cost)
Column | Type | Description |
---|---|---|
start_vid | BIGINT |
Identifier of the starting vertex. |
end_vid | BIGINT |
Identifier of the ending vertex. |
agg_cost | FLOAT |
Aggregate cost from start_vid to end_vid . |
See Also¶
- aStar - Family of functions
- Cost - Category
- Cost Matrix - Category
- Examples use Sample Data network.
Indices and tables