# pgr_turnRestrictedPath - Experimental¶

pgr_turnRestrictedPath Using Yen’s algorithm Vertex -Vertex routing with restrictions

Warning

Possible server crash

• These functions might create a server crash

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

Availability

• Version 3.0.0

• New Experimental function

## Description¶

Using Yen’s algorithm to obtain K shortest paths and analyze the paths to select the paths that do not use the restrictions

## Signatures¶

pgr_turnRestrictedPath(Edges SQL, Restrictions SQL, Start vid, End vid, K cycles,
[, directed] [,heap_paths] [, stop_on_first] [,strict])
RETURNS SETOF (seq, path_id, path_seq, node, edge, cost, agg_cost)
Example:

From vertex $$3$$ to vertex $$8$$ on a directed graph

SELECT * FROM pgr_turnRestrictedPath(
$$SELECT id, source, target, cost, reverse_cost FROM edges$$,
$$SELECT path, cost FROM new_restrictions$$,
3, 8, 3);
seq | path_id | path_seq | node | edge | cost | agg_cost
-----+---------+----------+------+------+------+----------
1 |       1 |        1 |    3 |    7 |    1 | Infinity
2 |       1 |        2 |    7 |   10 |    1 |        1
3 |       1 |        3 |    8 |   -1 |    0 |        2
(3 rows)



## Parameters¶

Column

Type

Description

Edges SQL

TEXT

SQL query as described.

start vid

ANY-INTEGER

Identifier of the departure vertex.

end vid

ANY-INTEGER

Identifier of the departure vertex.

K

ANY-INTEGER

Number of required paths

Where:

ANY-INTEGER:

SMALLINT, INTEGER, BIGINT

### Optional parameters¶

Column

Type

Default

Description

directed

BOOLEAN

true

• When true the graph is considered Directed

• When false the graph is considered as Undirected.

## KSP Optional parameters¶

Column

Type

Default

Description

heap_paths

BOOLEAN

false

• When false Returns at most K paths

• When true all the calculated paths while processing are returned.

• Roughly, when the shortest path has N edges, the heap will contain about than N * K paths for small value of K and K > 5.

## Special optional parameters¶

Column

Type

Default

Description

stop_on_first

BOOLEAN

true

• When true stops on first path found that dos not violate restrictions

• When false returns at most K paths

strict

BOOLEAN

false

• When true returns only paths that do not violate restrictions

• When false returns the paths found

## Inner Queries¶

### Edges SQL¶

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)

• When negative: edge (target, source) does not exist, therefore it’s not part of the graph.

Where:

ANY-INTEGER:

SMALLINT, INTEGER, BIGINT

ANY-NUMERICAL:

SMALLINT, INTEGER, BIGINT, REAL, FLOAT

### Restrictions SQL¶

Column

Type

Description

path

ARRAY[ ANY-INTEGER ]

Sequence of edge identifiers that form a path that is not allowed to be taken. - Empty arrays or NULL arrays are ignored. - Arrays that have a NULL element will raise an exception.

Cost

ANY-NUMERICAL

Cost of taking the forbidden path.

Where:

ANY-INTEGER:

SMALLINT, INTEGER, BIGINT

ANY-NUMERICAL:

SMALLINT, INTEGER, BIGINT, REAL, FLOAT

## Result Columns¶

Returns set of (seq, path_id, path_seq, start_vid, end_vid, node, edge, cost, agg_cost)

Column

Type

Description

seq

INTEGER

Sequential value starting from 1.

path_id

INTEGER

Path identifier.

• Has value 1 for the first of a path from start_vid to end_vid.

path_seq

INTEGER

Relative position in the path. Has value 1 for the beginning of a path.

start_vid

BIGINT

Identifier of the starting vertex.

end_vid

BIGINT

Identifier of the ending vertex.

node

BIGINT

Identifier of the node in the path from start_vid to end_vid.

edge

BIGINT

Identifier of the edge used to go from node to the next node in the path sequence. -1 for the last node of the path.

cost

FLOAT

Cost to traverse from node using edge to the next node in the path sequence.

agg_cost

FLOAT

Aggregate cost from start_vid to node.

Example:

From vertex $$3$$ to $$8$$ with strict flag on.

SELECT * FROM pgr_turnRestrictedPath(
$$SELECT id, source, target, cost, reverse_cost FROM edges$$,
$$SELECT path, cost FROM new_restrictions$$,
3, 8, 3,
strict => true);
seq | path_id | path_seq | node | edge | cost | agg_cost
-----+---------+----------+------+------+------+----------
(0 rows)


Example:

From vertex $$3$$ to vertex $$8$$ on an undirected graph

SELECT * FROM pgr_turnRestrictedPath(
$$SELECT id, source, target, cost, reverse_cost FROM edges$$,
$$SELECT path, cost FROM new_restrictions$$,
3, 8, 3,
directed => false);
seq | path_id | path_seq | node | edge | cost | agg_cost
-----+---------+----------+------+------+------+----------
1 |       1 |        1 |    3 |    7 |    1 |        0
2 |       1 |        2 |    7 |    4 |    1 |        1
3 |       1 |        3 |    6 |    2 |    1 |        2
4 |       1 |        4 |   10 |    5 |    1 |        3
5 |       1 |        5 |   11 |   11 |    1 |        4
6 |       1 |        6 |   12 |   12 |    1 |        5
7 |       1 |        7 |    8 |   -1 |    0 |        6
(7 rows)


Example:

From vertex $$3$$ to vertex $$8$$ with more alternatives

SELECT * FROM pgr_turnRestrictedPath(
$$SELECT id, source, target, cost, reverse_cost FROM edges$$,
$$SELECT path, cost FROM new_restrictions$$,
3, 8, 3,
directed => false,
heap_paths => true,
stop_on_first => false);
seq | path_id | path_seq | node | edge | cost | agg_cost
-----+---------+----------+------+------+------+----------
1 |       1 |        1 |    3 |    7 |    1 |        0
2 |       1 |        2 |    7 |    4 |    1 |        1
3 |       1 |        3 |    6 |    2 |    1 |        2
4 |       1 |        4 |   10 |    5 |    1 |        3
5 |       1 |        5 |   11 |   11 |    1 |        4
6 |       1 |        6 |   12 |   12 |    1 |        5
7 |       1 |        7 |    8 |   -1 |    0 |        6
8 |       2 |        1 |    3 |    7 |    1 |        0
9 |       2 |        2 |    7 |    8 |    1 |        1
10 |       2 |        3 |   11 |    9 |    1 |        2
11 |       2 |        4 |   16 |   15 |    1 |        3
12 |       2 |        5 |   17 |   13 |    1 |        4
13 |       2 |        6 |   12 |   12 |    1 |        5
14 |       2 |        7 |    8 |   -1 |    0 |        6
(14 rows)