pgr_biconnectedComponents
¶
pgr_biconnectedComponents
— Biconnected components of an undirected graph.
Availability
- Version 3.0.0
- Return columns change:
n_seq
is removedseq
changed type toBIGINT
- Official function
- Return columns change:
- Version 2.5.0
- New experimental function
Description¶
The biconnected components of an undirected graph are the maximal subsets of vertices such that the removal of a vertex from particular component will not disconnect the component. Unlike connected components, vertices may belong to multiple biconnected components. Vertices can be present in multiple biconnected components, but each edge can only be contained in a single biconnected component.
The main characteristics are:
- Works for undirected graphs.
- Components are described by edges.
- The returned values are ordered:
component
ascending.edge
ascending.
- Running time: \(O(V + E)\)
Signatures¶
pgr_biconnectedComponents(Edges SQL) RETURNS SET OF (seq, component, edge) OR EMPTY SET
Example: | The biconnected components of the graph |
---|
SELECT * FROM pgr_biconnectedComponents(
'SELECT id, source, target, cost, reverse_cost FROM edges'
);
seq | component | edge
-----+-----------+------
1 | 1 | 1
2 | 2 | 2
3 | 2 | 3
4 | 2 | 4
5 | 2 | 5
6 | 2 | 8
7 | 2 | 9
8 | 2 | 10
9 | 2 | 11
10 | 2 | 12
11 | 2 | 13
12 | 2 | 15
13 | 2 | 16
14 | 6 | 6
15 | 7 | 7
16 | 14 | 14
17 | 17 | 17
18 | 18 | 18
(18 rows)
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 (
|
Where:
ANY-INTEGER: | SMALLINT , INTEGER , BIGINT |
---|---|
ANY-NUMERICAL: | SMALLINT , INTEGER , BIGINT , REAL , FLOAT |
Result Columns¶
Returns set of (seq, component, edge)
Column | Type | Description |
---|---|---|
seq |
BIGINT |
Sequential value starting from 1. |
component |
BIGINT |
Component identifier.
|
edge |
BIGINT |
Identifier of the edge that belongs to the component . |
See Also¶
- Components - Family of functions
- The queries use the Sample Data network.
- Boost: Biconnected components
- wikipedia: Biconnected component
Indices and tables