pgr_withPointsCost - Proposed¶
Name¶
pgr_withPointsCost - Calculates the shortest path and returns only the aggregate cost of the shortest path(s) found, for the combination of points given.
Warning
These are 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.
Synopsis¶
Modify the graph to include points defined by points_sql. Using Dijkstra algorithm, return only the aggregate cost of the shortest path(s) found.
Characteristics:¶
- The main Characteristics are:
- It does not return a path.
- Returns the sum of the costs of the shortest path for pair combination of vertices in the modified graph.
- Vertices of the graph are:
- positive when it belongs to the edges_sql
- negative when it belongs to the points_sql
- Process is done only on edges with positive costs.
- Values are returned when there is a path.
- The returned values are in the form of a set of (start_vid, end_vid, agg_cost).
- When the starting vertex and ending vertex are the same, there is no path.
- The agg_cost in the non included values (v, v) is 0
- When the starting vertex and ending vertex are the different and there is no path.
- The agg_cost in the non included values (u, v) is \(\infty\)
- If the values returned are stored in a table, the unique index would be the pair: (start_vid, end_vid).
- For undirected graphs, the results are symmetric.
- The agg_cost of (u, v) is the same as for (v, u).
- For optimization purposes, any duplicated value in the start_vids or end_vids is ignored.
- The returned values are ordered:
- start_vid ascending
- end_vid ascending
- Running time: \(O(| start\_vids | * (V \log V + E))\)
Signature Summary¶
pgr_withPointsCost(edges_sql, points_sql, start_vid, end_vid, directed, driving_side)
pgr_withPointsCost(edges_sql, points_sql, start_vid, end_vids, directed, driving_side)
pgr_withPointsCost(edges_sql, points_sql, start_vids, end_vid, directed, driving_side)
pgr_withPointsCost(edges_sql, points_sql, start_vids, end_vids, directed, driving_side)
RETURNS SET OF (start_vid, end_vid, agg_cost)
Note
There is no details flag, unlike the other members of the withPoints family of functions.
Signatures¶
Minimal Use¶
- The minimal signature:
- Is for a directed graph.
- The driving side is set as b both. So arriving/departing to/from the point(s) can be in any direction.
pgr_withPointsCost(edges_sql, points_sql, start_vid, end_vid)
RETURNS SET OF (start_vid, end_vid, agg_cost)
Example: |
---|
SELECT * FROM pgr_withPointsCost(
'SELECT id, source, target, cost, reverse_cost FROM edge_table ORDER BY id',
'SELECT pid, edge_id, fraction, side from pointsOfInterest',
-1, -3);
start_pid | end_pid | agg_cost
-----------+---------+----------
-1 | -3 | 3.2
(1 row)
One to One¶
pgr_withPointsCost(edges_sql, points_sql, start_vid, end_vid,
directed:=true, driving_side:='b')
RETURNS SET OF (seq, node, edge, cost, agg_cost)
Example: |
---|
SELECT * FROM pgr_withPointsCost(
'SELECT id, source, target, cost, reverse_cost FROM edge_table ORDER BY id',
'SELECT pid, edge_id, fraction, side from pointsOfInterest',
-1, 3,
directed := false);
start_pid | end_pid | agg_cost
-----------+---------+----------
-1 | 3 | 1.6
(1 row)
One to Many¶
pgr_withPointsCost(edges_sql, points_sql, start_vid, end_vids,
directed:=true, driving_side:='b')
RETURNS SET OF (start_vid, end_vid, agg_cost)
Example: |
---|
SELECT * FROM pgr_withPointsCost(
'SELECT id, source, target, cost, reverse_cost FROM edge_table ORDER BY id',
'SELECT pid, edge_id, fraction, side from pointsOfInterest',
-1, ARRAY[-3,5]);
start_pid | end_pid | agg_cost
-----------+---------+----------
-1 | -3 | 3.2
-1 | 5 | 1.6
(2 rows)
Many to One¶
pgr_withPointsCost(edges_sql, points_sql, start_vids, end_vid,
directed:=true, driving_side:='b')
RETURNS SET OF (start_vid, end_vid, agg_cost)
Example: |
---|
SELECT * FROM pgr_withPointsCost(
'SELECT id, source, target, cost, reverse_cost FROM edge_table ORDER BY id',
'SELECT pid, edge_id, fraction, side from pointsOfInterest',
ARRAY[-1,2], -3);
start_pid | end_pid | agg_cost
-----------+---------+----------
-1 | -3 | 3.2
2 | -3 | 2.6
(2 rows)
Many to Many¶
pgr_withPointsCost(edges_sql, points_sql, start_vids, end_vids,
directed:=true, driving_side:='b')
RETURNS SET OF (start_vid, end_vid, agg_cost)
Example: |
---|
SELECT * FROM pgr_withPointsCost(
'SELECT id, source, target, cost, reverse_cost FROM edge_table ORDER BY id',
'SELECT pid, edge_id, fraction, side from pointsOfInterest',
ARRAY[-1,2], ARRAY[-3,7]);
start_pid | end_pid | agg_cost
-----------+---------+----------
-1 | -3 | 3.2
-1 | 7 | 3.6
2 | -3 | 2.6
2 | 7 | 3
(4 rows)
Description of the Signatures¶
Description of the edges_sql 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 |
|
|
reverse_cost | ANY-NUMERICAL | -1 |
|
Where:
ANY-INTEGER: | SMALLINT, INTEGER, BIGINT |
---|---|
ANY-NUMERICAL: | SMALLINT, INTEGER, BIGINT, REAL, FLOAT |
Description of the Points SQL query¶
points_sql: | an SQL query, which should return a set of rows with the following columns: |
---|
Column | Type | Description |
---|---|---|
pid | ANY-INTEGER |
|
edge_id | ANY-INTEGER | Identifier of the “closest” edge to the point. |
fraction | ANY-NUMERICAL | Value in <0,1> that indicates the relative postition from the first end point of the edge. |
side | CHAR |
|
Where:
ANY-INTEGER: | smallint, int, bigint |
---|---|
ANY-NUMERICAL: | smallint, int, bigint, real, float |
Description of the parameters of the signatures¶
Parameter | Type | Description |
---|---|---|
edges_sql | TEXT | Edges SQL query as described above. |
points_sql | TEXT | Points SQL query as described above. |
start_vid | ANY-INTEGER | Starting vertex identifier. When negative: is a point’s pid. |
end_vid | ANY-INTEGER | Ending vertex identifier. When negative: is a point’s pid. |
start_vids | ARRAY[ANY-INTEGER] | Array of identifiers of starting vertices. When negative: is a point’s pid. |
end_vids | ARRAY[ANY-INTEGER] | Array of identifiers of ending vertices. When negative: is a point’s pid. |
directed | BOOLEAN | (optional). When false the graph is considered as Undirected. Default is true which considers the graph as Directed. |
driving_side | CHAR |
|
Description of the return values¶
Returns set of (start_vid, end_vid, agg_cost)
Column | Type | Description |
---|---|---|
start_vid | BIGINT | Identifier of the starting vertex. When negative: is a point’s pid. |
end_vid | BIGINT | Identifier of the ending point. When negative: is a point’s pid. |
agg_cost | FLOAT | Aggregate cost from start_vid to end_vid. |
Examples¶
Example: | With right side driving topology. |
---|
SELECT * FROM pgr_withPointsCost(
'SELECT id, source, target, cost, reverse_cost FROM edge_table ORDER BY id',
'SELECT pid, edge_id, fraction, side from pointsOfInterest',
ARRAY[-1,2], ARRAY[-3,7],
driving_side := 'l');
start_pid | end_pid | agg_cost
-----------+---------+----------
-1 | -3 | 3.2
-1 | 7 | 3.6
2 | -3 | 2.6
2 | 7 | 3
(4 rows)
Example: | With left side driving topology. |
---|
SELECT * FROM pgr_withPointsCost(
'SELECT id, source, target, cost, reverse_cost FROM edge_table ORDER BY id',
'SELECT pid, edge_id, fraction, side from pointsOfInterest',
ARRAY[-1,2], ARRAY[-3,7],
driving_side := 'r');
start_pid | end_pid | agg_cost
-----------+---------+----------
-1 | -3 | 4
-1 | 7 | 4.4
2 | -3 | 2.6
2 | 7 | 3
(4 rows)
Example: | Does not matter driving side. |
---|
SELECT * FROM pgr_withPointsCost(
'SELECT id, source, target, cost, reverse_cost FROM edge_table ORDER BY id',
'SELECT pid, edge_id, fraction, side from pointsOfInterest',
ARRAY[-1,2], ARRAY[-3,7],
driving_side := 'b');
start_pid | end_pid | agg_cost
-----------+---------+----------
-1 | -3 | 3.2
-1 | 7 | 3.6
2 | -3 | 2.6
2 | 7 | 3
(4 rows)
The queries use the Sample Data network.
History
- Proposed in version 2.2