pgr_biconnectedComponents - pgRouting Manual (3.2)

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:

• The signature is for an undirected graph.

• 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 edge_table'
);
 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)

Parameters

Inner query

edges SQL :

an SQL query of an undirected graph, which should return a set of rows with the following columns:

Where:

ANY-INTEGER :

SMALLINT, INTEGER, BIGINT

ANY-NUMERICAL :

SMALLINT, INTEGER, BIGINT, REAL, FLOAT

Result Columns

Returns set of (seq, component, edge)

See Also

• Components - Family of functions

• The queries use the Sample Data network.

• Boost: Biconnected components

• wikipedia: Biconnected component

Indices and tables

• Index

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