/**
* Add edges from one source vertex to multiple target vertices. Whether duplicates are created
* depends on the underlying {@link DirectedGraph} implementation.
*
* @param graph graph to be mutated
* @param source source vertex of the new edges
* @param targets target vertices for the new edges
* @param <V> the graph vertex type
* @param <E> the graph edge type
*/
public static void addOutgoingEdges <V, E>(Graph <V, E> graph, V source, ICollection <V> targets)
{
if (!graph.containsVertex(source))
{
graph.addVertex(source);
}
foreach (V target in targets)
{
if (!graph.containsVertex(target))
{
graph.addVertex(target);
}
graph.addEdge(source, target);
}
}
/**
* Add edges from multiple source vertices to one target vertex. Whether duplicates are created
* depends on the underlying {@link Graph} implementation.
*
* @param graph graph to be mutated
* @param target target vertex for the new edges
* @param sources source vertices for the new edges
* @param <V> the graph vertex type
* @param <E> the graph edge type
*/
public static void addIncomingEdges <V, E>(Graph <V, E> graph, V target, ICollection <V> sources)
{
if (!graph.containsVertex(target))
{
graph.addVertex(target);
}
foreach (V source in sources)
{
if (!graph.containsVertex(source))
{
graph.addVertex(source);
}
graph.addEdge(source, target);
}
}
/**
* Removes the given vertex from the given graph. If the vertex to be removed has one or more
* predecessors, the predecessors will be connected directly to the successors of the vertex to
* be removed.
*
* @param graph graph to be mutated
* @param vertex vertex to be removed from this graph, if present
* @param <V> the graph vertex type
* @param <E> the graph edge type
*
* @return true if the graph contained the specified vertex; false otherwise.
*/
public static bool removeVertexAndPreserveConnectivity <V, E>(Graph <V, E> graph, V vertex)
{
if (!graph.containsVertex(vertex))
{
return(false);
}
if (vertexHasPredecessors(graph, vertex))
{
List <V> predecessors = Graphs.predecessorListOf(graph, vertex);
List <V> successors = Graphs.successorListOf(graph, vertex);
foreach (V predecessor in predecessors)
{
addOutgoingEdges(graph, predecessor, successors);
}
}
graph.removeVertex(vertex);
return(true);
}
