pgr_bdAstarCost - Proposed¶
Name¶
pgr_bdAstarCost
— Returns the shortest path using A* 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_bdAstarCost(edges_sql, start_vid, end_vid)
pgr_bdAstarCost(edges_sql, start_vid, end_vid [, directed , heuristic, factor, epsilon])
pgr_bdAstarCost(edges_sql, start_vid, end_vids [, directed, heuristic, factor, epsilon])
pgr_bdAstarCost(edges_sql, start_vids, end_vid [, directed, heuristic, factor, epsilon])
pgr_bdAstarCost(edges_sql, start_vids, end_vids [, directed, heuristic, factor, epsilon])
RETURNS SET OF (start_vid, end_vid, agg_cost)
OR EMPTY SET
Using these signatures, will load once the graph and perform several one to one pgr_bdAstarCost
- The result is the union of the results of the one to one pgr_bdAstarCost.
- The extra
start_vid
and/orend_vid
in the result is used to distinguish to which path it belongs.
Signatures¶
Minimal Signature¶
pgr_bdAstarCost(edges_sql, start_vid, end_vid)
RETURNS SET OF (start_vid, end_vid, 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_bdAstarCost(
'SELECT id, source, target, cost, reverse_cost, x1,y1,x2,y2
FROM edge_table',
2, 3
);
start_vid | end_vid | agg_cost
-----------+---------+----------
2 | 3 | 10
(1 row)
pgr_bdAstarCost One to One¶
pgr_bdAstarCost(edges_sql, start_vid, end_vid [, directed, heuristic, factor, epsilon])
RETURNS SET OF (start_vid, end_vid, agg_cost)
- 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
- 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_bdAstarCost(
'SELECT id, source, target, cost, reverse_cost, x1,y1,x2,y2
FROM edge_table',
2, 3,
true, heuristic := 2
);
start_vid | end_vid | agg_cost
-----------+---------+----------
2 | 3 | 6
(1 row)
pgr_bdAstarCost One to many¶
pgr_bdAstarCost(edges_sql, start_vid, end_vids [, directed, heuristic, factor, epsilon])
RETURNS SET OF (start_vid, end_vid, agg_cost)
- 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_bdAstarCost(
'SELECT id, source, target, cost, reverse_cost, x1,y1,x2,y2
FROM edge_table',
2, ARRAY[3, 11],
heuristic := 3, factor := 3.5
);
start_vid | end_vid | agg_cost
-----------+---------+----------
2 | 3 | 66.25
2 | 11 | 27.5
(2 rows)
pgr_bdAstarCost Many to One¶
pgr_bdAstarCost(edges_sql, start_vids, end_vid [, directed, heuristic, factor, epsilon])
RETURNS SET OF (start_vid, end_vid, agg_cost)
- 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_bdAstarCost(
'SELECT id, source, target, cost, reverse_cost, x1,y1,x2,y2
FROM edge_table',
ARRAY[2, 7], 3,
false, heuristic := 4
);
start_vid | end_vid | agg_cost
-----------+---------+------------------
2 | 3 | 1
7 | 3 | 7.65028153987288
(2 rows)
pgr_bdAstarCost Many to Many¶
pgr_bdAstarCost(edges_sql, start_vids, end_vids [, directed, heuristic, factor, epsilon])
RETURNS SET OF (start_vid, end_vid, agg_cost)
- 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_bdAstarCost(
'SELECT id, source, target, cost, reverse_cost, x1,y1,x2,y2
FROM edge_table',
ARRAY[2, 7], ARRAY[3, 11],
factor := 0.5
);
start_vid | end_vid | agg_cost
-----------+---------+----------
2 | 3 | 7.5
2 | 11 | 4
7 | 3 | 11.5
7 | 11 | 6.5
(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. |
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 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 . |