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| <Head> |
| <Title>Boost Graph Library: make_connected</Title> |
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| |
| <H1><tt>make_connected</tt></H1> |
| |
| <p> |
| |
| <pre> |
| template <typename Graph, typename VertexIndexMap, typename AddEdgeVisitor> |
| make_connected(Graph& g, VertexIndexMap vm, AddEdgeVisitor& vis); |
| </pre> |
| |
| <p> |
| |
| A undirected graph <i>G</i> is connected if, for every pair of vertices |
| <i>u,v</i> in <i>G</i>, there is a path from <i>u</i> to <i>v</i>. |
| <tt>make_connected</tt> adds the minimum number of edges needed to make the |
| input graph connected. The algorithm first identifies all of the |
| <a href="./connected_components.html">connected components</a> in the graph, |
| then adds edges to connect those components together in a path. For example, if |
| a graph contains three connected components <i>A</i>, <i>B</i>, and <i>C</i>, |
| <tt>make_connected</tt> will add two edges. The two edges added might consist |
| of one connecting a vertex in <i>A</i> with a vertex in <i>B</i> and one |
| connecting a vertex in <i>B</i> with a vertex in <i>C</i>. |
| <p> |
| The default behavior of <tt>make_connected</tt> is to modify the graph |
| <tt>g</tt> by calling <tt>add_edge(u,v,g)</tt> for every pair of vertices |
| <i>(u,v)</i> where an edge needs to be added to connect <tt>g</tt>. This |
| behavior can be overriden by providing a vistor as the <tt>AddEdgeVisitor</tt> |
| parameter. The only requirement for an <tt>AddEdgeVisitor</tt> is that it |
| define a member function with the following signature: |
| <pre> |
| template <typename Graph, typename Vertex> |
| void visit_vertex_pair(Vertex u, Vertex v, Graph& g); |
| </pre> |
| This event point can also be used as a hook to update the underlying edge |
| index map automatically as edges are added. See the |
| documentation for the <a href="./AddEdgeVisitor.html">AddEdgeVisitor</a> |
| concept for more information. |
| |
| |
| <H3>Where Defined</H3> |
| |
| <P> |
| <a href="../../../boost/graph/make_connected.hpp"> |
| <TT>boost/graph/make_connected.hpp</TT> |
| </a> |
| |
| <h3>Parameters</h3> |
| |
| IN/OUT: <tt>Graph& g</tt> |
| |
| <blockquote> |
| An undirected graph. The graph type must be a model of <a |
| href="VertexListGraph.html">Vertex List Graph</a>, <a |
| href="IncidenceGraph.html">Incidence Graph</a>, and |
| a <a href="MutableGraph.html">Mutable Graph</a><br> |
| </blockquote> |
| |
| IN: <tt>VertexIndexMap vm</tt> |
| |
| <blockquote> |
| A <a href="../../property_map/doc/ReadablePropertyMap.html">Readable Property Map |
| </a> that maps vertices from <tt>g</tt> to distinct integers in the range |
| <tt>[0, num_vertices(g) )</tt><br> |
| <b>Default</b>: <tt>get(vertex_index,g)</tt><br> |
| </blockquote> |
| |
| IN: <tt>AddEdgeVisitor</tt> |
| |
| <blockquote> |
| A model of <a href="AddEdgeVisitor.html">AddEdgeVisitor |
| </a>.<br> |
| <b>Default</b>: <tt>default_add_edge_visitor</tt>, a class defines |
| <tt>visit_vertex_pair</tt> to dispatch |
| its calls to <tt>add_edge</tt>. |
| </blockquote> |
| |
| |
| |
| <h3>Complexity</h3> |
| |
| On a graph with <i>n</i> vertices and <i>m</i> edges, <tt>make_connected</tt> |
| runs in time <i>O(n + m)</i> |
| |
| <H3>Example</H3> |
| |
| <P> |
| <a href="../example/make_connected.cpp"> |
| <TT>../example/make_connected.cpp</TT> |
| </a> |
| |
| <h3>See Also</h3> |
| |
| <a href="planar_graphs.html">Planar Graphs in the Boost Graph Library</a> |
| |
| <br> |
| <HR> |
| Copyright © 2007 Aaron Windsor (<a href="mailto:aaron.windsor@gmail.com"> |
| aaron.windsor@gmail.com</a>) |
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