pgr_withPointsKSP¶
Name¶
pgr_withPointsKSP - Find the K shortest paths using Yen’s algorithm.
Note
This is a proposed function for version 2.3.
- Is not officially in the version 2.2 release.
Boost Graph Inside
Synopsis¶
Modifies the graph to include the points defined in the points_sql and using Yen algorithm, finds the K shortest paths.
Signature Summary¶
pgr_withPointsKSP(edges_sql, points_sql, start_pid, end_pid, K)
pgr_withPointsKSP(edges_sql, points_sql, start_pid, end_pid, K, directed, heap_paths, driving_side, details)
RETURNS SET OF (seq, path_id, path_seq, node, edge, cost, agg_cost)
Signatures¶
Minimal Usage¶
- The minimal usage:
- 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.
- No details are given about distance of other points of the query.
- No heap paths are returned.
pgr_withPointsKSP(edges_sql, points_sql, start_pid, end_pid, K)
RETURNS SET OF (seq, path_id, path_seq, node, edge, cost, agg_cost)
| Example: |
|---|
SELECT * FROM pgr_withPointsKSP(
'SELECT id, source, target, cost, reverse_cost FROM edge_table ORDER BY id',
'SELECT pid, edge_id, fraction, side from pointsOfInterest',
-1, -2, 2);
seq | path_id | path_seq | node | edge | cost | agg_cost
-----+---------+----------+------+------+------+----------
1 | 1 | 1 | -1 | 1 | 0.6 | 0
2 | 1 | 2 | 2 | 4 | 1 | 0.6
3 | 1 | 3 | 5 | 8 | 1 | 1.6
4 | 1 | 4 | 6 | 9 | 1 | 2.6
5 | 1 | 5 | 9 | 15 | 0.4 | 3.6
6 | 1 | 6 | -2 | -1 | 0 | 4
7 | 2 | 1 | -1 | 1 | 0.6 | 0
8 | 2 | 2 | 2 | 4 | 1 | 0.6
9 | 2 | 3 | 5 | 8 | 1 | 1.6
10 | 2 | 4 | 6 | 11 | 1 | 2.6
11 | 2 | 5 | 11 | 13 | 1 | 3.6
12 | 2 | 6 | 12 | 15 | 0.6 | 4.6
13 | 2 | 7 | -2 | -1 | 0 | 5.2
(13 rows)
Complete Signature¶
Finds the K shortest paths depending on the optional parameters setup.
pgr_withPointsKSP(edges_sql, points_sql, start_pid, end_pid, K,
directed:=true, heap_paths:=false, driving_side:='b', details:=false)
RETURNS SET OF (seq, path_id, path_seq, node, edge, cost, agg_cost)
| Example: | With details. |
|---|
SELECT * FROM pgr_withPointsKSP(
'SELECT id, source, target, cost, reverse_cost FROM edge_table ORDER BY id',
'SELECT pid, edge_id, fraction, side from pointsOfInterest',
-1, 6, 2, details := true);
seq | path_id | path_seq | node | edge | cost | agg_cost
-----+---------+----------+------+------+------+----------
1 | 1 | 1 | -1 | 1 | 0.6 | 0
2 | 1 | 2 | 2 | 4 | 0.7 | 0.6
3 | 1 | 3 | -6 | 4 | 0.3 | 1.3
4 | 1 | 4 | 5 | 8 | 1 | 1.6
5 | 1 | 5 | 6 | -1 | 0 | 2.6
6 | 2 | 1 | -1 | 1 | 0.6 | 0
7 | 2 | 2 | 2 | 4 | 0.7 | 0.6
8 | 2 | 3 | -6 | 4 | 0.3 | 1.3
9 | 2 | 4 | 5 | 10 | 1 | 1.6
10 | 2 | 5 | 10 | 12 | 0.6 | 2.6
11 | 2 | 6 | -3 | 12 | 0.4 | 3.2
12 | 2 | 7 | 11 | 13 | 1 | 3.6
13 | 2 | 8 | 12 | 15 | 0.6 | 4.6
14 | 2 | 9 | -2 | 15 | 0.4 | 5.2
15 | 2 | 10 | 9 | 9 | 1 | 5.6
16 | 2 | 11 | 6 | -1 | 0 | 6.6
(16 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 | 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), If negative: edge (source, target) does not exist, therefore it’s not part of the graph. |
| reverse_cost | ANY-NUMERICAL | (optional) Weight of the edge (target, source), If negative: edge (target, source) does not exist, therefore it’s not part of the graph. |
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 decribed above. |
| points_sql | TEXT | Points SQL query as decribed above. |
| start_pid | ANY-INTEGER | Starting point id. |
| end_pid | ANY-INTEGER | Ending point id. |
| K | INTEGER | Number of shortest paths. |
| directed | BOOLEAN | (optional). When false the graph is considered as Undirected. Default is true which considers the graph as Directed. |
| heap_paths | BOOLEAN | (optional). When true the paths calculated to get the shortests paths will be returned also. Default is false only the K shortest paths are returned. |
| driving_side | CHAR |
|
| details | BOOLEAN | (optional). When true the results will include the driving distance to the points with in the distance. Default is false which ignores other points of the points_sql. |
Description of the return values¶
Returns set of (seq, path_id, path_seq, node, edge, cost, agg_cost)
| Column | Type | Description |
|---|---|---|
| seq | INTEGER | Row sequence. |
| path_seq | INTEGER | Relative position in the path of node and edge. Has value 1 for the begining of a path. |
| path_id | INTEGER | Path identifier. The ordering of the paths: For two paths i, j if i < j then agg_cost(i) <= agg_cost(j). |
| node | BIGINT | Identifier of the node in the path. Negative values are the identifiers of a point. |
| edge | BIGINT |
|
| cost | FLOAT |
|
| agg_cost | FLOAT |
|
Examples¶
| Example: | Left side driving topology with details. |
|---|
SELECT * FROM pgr_withPointsKSP(
'SELECT id, source, target, cost, reverse_cost FROM edge_table ORDER BY id',
'SELECT pid, edge_id, fraction, side from pointsOfInterest',
-1, -2, 2,
driving_side := 'l', details := true);
seq | path_id | path_seq | node | edge | cost | agg_cost
-----+---------+----------+------+------+------+----------
1 | 1 | 1 | -1 | 1 | 0.6 | 0
2 | 1 | 2 | 2 | 4 | 0.7 | 0.6
3 | 1 | 3 | -6 | 4 | 0.3 | 1.3
4 | 1 | 4 | 5 | 8 | 1 | 1.6
5 | 1 | 5 | 6 | 11 | 1 | 2.6
6 | 1 | 6 | 11 | 13 | 1 | 3.6
7 | 1 | 7 | 12 | 15 | 0.6 | 4.6
8 | 1 | 8 | -2 | -1 | 0 | 5.2
9 | 2 | 1 | -1 | 1 | 0.6 | 0
10 | 2 | 2 | 2 | 4 | 0.7 | 0.6
11 | 2 | 3 | -6 | 4 | 0.3 | 1.3
12 | 2 | 4 | 5 | 8 | 1 | 1.6
13 | 2 | 5 | 6 | 9 | 1 | 2.6
14 | 2 | 6 | 9 | 15 | 1 | 3.6
15 | 2 | 7 | 12 | 15 | 0.6 | 4.6
16 | 2 | 8 | -2 | -1 | 0 | 5.2
(16 rows)
| Example: | Right side driving topology with heap paths and details. |
|---|
SELECT * FROM pgr_withPointsKSP(
'SELECT id, source, target, cost, reverse_cost FROM edge_table ORDER BY id',
'SELECT pid, edge_id, fraction, side from pointsOfInterest',
-1, -2, 2,
heap_paths := true, driving_side := 'r', details := true);
seq | path_id | path_seq | node | edge | cost | agg_cost
-----+---------+----------+------+------+------+----------
1 | 1 | 1 | -1 | 1 | 0.4 | 0
2 | 1 | 2 | 1 | 1 | 1 | 0.4
3 | 1 | 3 | 2 | 4 | 0.7 | 1.4
4 | 1 | 4 | -6 | 4 | 0.3 | 2.1
5 | 1 | 5 | 5 | 8 | 1 | 2.4
6 | 1 | 6 | 6 | 9 | 1 | 3.4
7 | 1 | 7 | 9 | 15 | 0.4 | 4.4
8 | 1 | 8 | -2 | -1 | 0 | 4.8
9 | 2 | 1 | -1 | 1 | 0.4 | 0
10 | 2 | 2 | 1 | 1 | 1 | 0.4
11 | 2 | 3 | 2 | 4 | 0.7 | 1.4
12 | 2 | 4 | -6 | 4 | 0.3 | 2.1
13 | 2 | 5 | 5 | 8 | 1 | 2.4
14 | 2 | 6 | 6 | 11 | 1 | 3.4
15 | 2 | 7 | 11 | 13 | 1 | 4.4
16 | 2 | 8 | 12 | 15 | 1 | 5.4
17 | 2 | 9 | 9 | 15 | 0.4 | 6.4
18 | 2 | 10 | -2 | -1 | 0 | 6.8
19 | 3 | 1 | -1 | 1 | 0.4 | 0
20 | 3 | 2 | 1 | 1 | 1 | 0.4
21 | 3 | 3 | 2 | 4 | 0.7 | 1.4
22 | 3 | 4 | -6 | 4 | 0.3 | 2.1
23 | 3 | 5 | 5 | 10 | 1 | 2.4
24 | 3 | 6 | 10 | 12 | 0.6 | 3.4
25 | 3 | 7 | -3 | 12 | 0.4 | 4
26 | 3 | 8 | 11 | 13 | 1 | 4.4
27 | 3 | 9 | 12 | 15 | 1 | 5.4
28 | 3 | 10 | 9 | 15 | 0.4 | 6.4
29 | 3 | 11 | -2 | -1 | 0 | 6.8
(29 rows)
The queries use the Sample Data network.
History
- Proposed in version 2.2