/**
* Adds the specified edge to the graph, including its vertices if not already included.
*
* @param targetGraph the graph for which the specified edge to be added
* @param sourceGraph the graph in which the specified edge is already present
* @param edge edge to add
* @param <V> the graph vertex type
* @param <E> the graph edge type
*
* @return <tt>true</tt> if the target graph did not already contain the specified edge.
*/
public static bool addEdgeWithVertices <V, E>(Graph <V, E> targetGraph, Graph <V, E> sourceGraph, E edge)
{
V sourceVertex = sourceGraph.getEdgeSource(edge);
V targetVertex = sourceGraph.getEdgeTarget(edge);
targetGraph.addVertex(sourceVertex);
targetGraph.addVertex(targetVertex);
return(targetGraph.addEdge(sourceVertex, targetVertex, edge));
}
/**
* Adds all the vertices and all the edges of the specified source digraph to the specified
* destination digraph, reversing all of the edges. If you want to do this as a linked view of
* the source graph (rather than by copying to a destination graph), use
* {@link EdgeReversedGraph} instead.
*
* <p>
* The behavior of this operation is undefined if any of the specified graphs is modified while
* operation is in progress.
*
* @param destination the graph to which vertices and edges are added
* @param source the graph used as source for vertices and edges to add
* @param <V> the graph vertex type
* @param <E> the graph edge type
*
* @see EdgeReversedGraph
*/
public static void addGraphReversed <V, E>(Graph <V, E> destination, Graph <V, E> source)
{
if (!source.getType().isDirected() || !destination.getType().isDirected())
{
throw new ArgumentException("graph must be directed");
}
addAllVertices(destination, source.vertexSet());
foreach (E edge in source.edgeSet())
{
destination.addEdge(source.getEdgeTarget(edge), source.getEdgeSource(edge));
}
}
/**
* Adds a subset of the edges of the specified source graph to the specified destination graph.
* The behavior of this operation is undefined if either of the graphs is modified while the
* operation is in progress. {@link #addEdgeWithVertices} is used for the transfer, so source
* vertexes will be added automatically to the target graph.
*
* @param destination the graph to which edges are to be added
* @param source the graph used as a source for edges to add
* @param edges the edges to be added
* @param <V> the graph vertex type
* @param <E> the graph edge type
*
* @return <tt>true</tt> if this graph changed as a result of the call
*/
public static bool addAllEdges <V, E>(Graph <V, E> destination, Graph <V, E> source, ICollection <E> edges)
{
bool modified = false;
foreach (E e in edges)
{
V s = source.getEdgeSource(e);
V t = source.getEdgeTarget(e);
destination.addVertex(s);
destination.addVertex(t);
modified |= destination.addEdge(s, t, e);
}
return(modified);
}
/**
* Gets the vertex opposite another vertex across an edge.
*
* @param g graph containing e and v
* @param e edge in g
* @param v vertex in g
* @param <V> the graph vertex type
* @param <E> the graph edge type
*
* @return vertex opposite to v across e
*/
public static V getOppositeVertex <V, E>(Graph <V, E> g, E e, V v)
{
V source = g.getEdgeSource(e);
V target = g.getEdgeTarget(e);
if (v.Equals(source))
{
return(target);
}
else if (v.Equals(target))
{
return(source);
}
else
{
throw new ArgumentException("no such vertex: " + v.ToString());
}
}
/**
* Tests whether an edge is incident to a vertex.
*
* @param g graph containing e and v
* @param e edge in g
* @param v vertex in g
* @param <V> the graph vertex type
* @param <E> the graph edge type
*
* @return true iff e is incident on v
*/
public static bool testIncidence <V, E>(Graph <V, E> g, E e, V v)
{
return((g.getEdgeSource(e).Equals(v)) || (g.getEdgeTarget(e).Equals(v)));
}