..
   ****************************************************************************
    pgRouting Manual
    Copyright(c) pgRouting Contributors

    This documentation is licensed under a Creative Commons Attribution-Share
    Alike 3.0 License: http://creativecommons.org/licenses/by-sa/3.0/
   ****************************************************************************

.. index::
   single: Components Family ; pgr_makeConnected - Experimental
   single: makeConnected - Experimental on v3.2


|

``pgr_makeConnected`` - Experimental
===============================================================================

``pgr_makeConnected`` — Set of edges that will connect the graph.

.. include:: experimental.rst
   :start-after: warning-begin
   :end-before: end-warning

.. rubric:: Availability

* Version 3.2.0

  * New experimental function.


Description
-------------------------------------------------------------------------------

Adds the minimum number of edges needed to make the input graph connected. The
algorithm first identifies
all of the connected components in the graph, then adds edges to connect those
components together in a path.
For example, if a graph contains three connected components A, B, and C,
make_connected will add two edges.
The two edges added might consist of one connecting a vertex in A with a vertex
in B and one connecting a vertex in B with a vertex in C.

The main characteristics are:

- Works for **undirected** graphs.
- It will give a minimum list of all edges which are needed in the graph to
  make connect it.
- The algorithm does not considers traversal costs in the calculations.
- The algorithm does not considers geometric topology in the calculations.
- Running time: :math:`O(V + E)`

|Boost| Boost Graph Inside

Signatures
-------------------------------------------------------------------------------

.. admonition:: \ \
   :class: signatures

   | pgr_makeConnected(`Edges SQL`_)

   | Returns set of |result-component-make|
   | OR EMPTY SET

:Example: List of edges that are needed to connect the graph.

.. literalinclude:: makeConnected.queries
   :start-after: -- q1
   :end-before: -- q2

Parameters
-------------------------------------------------------------------------------

.. include:: pgRouting-concepts.rst
   :start-after: only_edge_param_start
   :end-before: only_edge_param_end

Inner Queries
-------------------------------------------------------------------------------

Edges SQL
...............................................................................

.. include:: pgRouting-concepts.rst
    :start-after: basic_edges_sql_start
    :end-before: basic_edges_sql_end

Result columns
-------------------------------------------------------------------------------

Returns set of |result-component-make|

.. list-table::
   :width: 81
   :widths: auto
   :header-rows: 1

   * - Column
     - Type
     - Description
   * - ``seq``
     - ``BIGINT``
     - Sequential value starting from **1**.
   * - ``start_vid``
     - ``BIGINT``
     - Identifier of the first end point vertex of the edge.
   * - ``end_vid``
     - ``BIGINT``
     - Identifier of the second end point vertex of the edge.

See Also
-------------------------------------------------------------------------------

* `Boost: make connected
  <https://www.boost.org/libs/graph/doc/make_connected.html>`__
* :doc:`sampledata`

.. rubric:: Indices and tables

* :ref:`genindex`
* :ref:`search`
