pgr_chinesePostman - Experimental¶
pgr_chinesePostman
— Calculates the shortest circuit path which contains
every edge in a directed graph and starts and ends on the same vertex.
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¶
The main characteristics are:
Process is done only on edges with positive costs.
Running time: \(O(E * (E + V * logV))\)
Graph must be connected.
Returns
EMPTY SET
on a disconnected graph
Signatures¶
pgr_chinesePostman(edges_sql)
RETURNS SET OF (seq, node, edge, cost, agg_cost)
OR EMPTY SET
- Example
SELECT * FROM pgr_chinesePostman(
'SELECT id,
source, target,
cost, reverse_cost FROM edge_table where id < 17'
);
seq | node | edge | cost | agg_cost
-----+------+------+------+----------
1 | 1 | 1 | 1 | 0
2 | 2 | 4 | 1 | 1
3 | 5 | 4 | 1 | 2
4 | 2 | 4 | 1 | 3
5 | 5 | 7 | 1 | 4
6 | 8 | 6 | 1 | 5
7 | 7 | 6 | 1 | 6
8 | 8 | 7 | 1 | 7
9 | 5 | 8 | 1 | 8
10 | 6 | 8 | 1 | 9
11 | 5 | 10 | 1 | 10
12 | 10 | 10 | 1 | 11
13 | 5 | 10 | 1 | 12
14 | 10 | 14 | 1 | 13
15 | 13 | 14 | 1 | 14
16 | 10 | 12 | 1 | 15
17 | 11 | 13 | 1 | 16
18 | 12 | 15 | 1 | 17
19 | 9 | 9 | 1 | 18
20 | 6 | 9 | 1 | 19
21 | 9 | 15 | 1 | 20
22 | 12 | 15 | 1 | 21
23 | 9 | 16 | 1 | 22
24 | 4 | 3 | 1 | 23
25 | 3 | 5 | 1 | 24
26 | 6 | 11 | 1 | 25
27 | 11 | 13 | 1 | 26
28 | 12 | 15 | 1 | 27
29 | 9 | 16 | 1 | 28
30 | 4 | 16 | 1 | 29
31 | 9 | 16 | 1 | 30
32 | 4 | 3 | 1 | 31
33 | 3 | 2 | 1 | 32
34 | 2 | 1 | 1 | 33
35 | 1 | -1 | 0 | 34
(35 rows)
Parameters¶
Column |
Type |
Default |
Description |
---|---|---|---|
edges_sql |
|
The edges SQL query as described in Inner query. |
Inner query¶
An Edges SQL that represents a directed graph with the following columns
Column |
Type |
Default |
Description |
---|---|---|---|
id |
|
Identifier of the edge. |
|
source |
|
Identifier of the first end point vertex of the edge. |
|
target |
|
Identifier of the second end point vertex of the edge. |
|
cost |
|
Weight of the edge (source, target)
|
|
reverse_cost |
|
-1 |
Weight of the edge (target, source),
|
Where:
- ANY-INTEGER
SMALLINT, INTEGER, BIGINT
- ANY-NUMERICAL
SMALLINT, INTEGER, BIGINT, REAL, FLOAT
Result Columns¶
Returns set of (seq, node, edge, cost, agg_cost)
Column |
Type |
Description |
---|---|---|
seq |
|
Sequential value starting from 1. |
node |
|
Identifier of the node in the path from |
edge |
|
Identifier of the edge used to go from |
cost |
|
Cost to traverse from |
agg_cost |
|
Aggregate cost from |
See Also¶
Indices and tables