Package com.jgalgo.graph

Interface EdgeSet<V,E>

Type Parameters:
V - the vertices type
E - the edges type
All Superinterfaces:
Collection<E>, Iterable<E>, Set<E>
All Known Subinterfaces:
IEdgeSet
public interface EdgeSet<V,E> extends Set<E>
Set of graph edges. 
 
 Graph<String, Integer> g = ...;
 String vertex = ...;
 for (EdgeIter<String, Integer> eit = g.outEdges(vertex).iterator(); eit.hasNext();) {
 	Integer e = eit.next();
 	String u = eit.source();
 	String v = eit.target();
 	assert vertex.equals(u);
 	System.out.println("Out edge of " + vertex + ": " + e + "(" + u + ", " + v + ")");
 }

Note that sets implementing this interface should define Object.equals(Object), Object.hashCode() and Object.toString() compatible with the Set interface. Namely, the above methods should not take into account the endpoints of the edges, only the edges identifiers themselves.

Author:
Barak Ugav
See Also:

  • Method Details

    • iterator

      EdgeIter<V,E> iterator()
      Return an edge iterator that iterate over the edges in this set.
      Specified by:
      iterator in interface Collection<V>
      Specified by:
      iterator in interface Iterable<V>
      Specified by:
      iterator in interface Set<V>

    • of

      static <V, E> EdgeSet<V,E> of(Set<E> edges, Graph<V,E> g)
      Create an edge set object from a plain set of edges.

      A 'plain' set of edges is a set of the edges identifiers. It does not include any information about the endpoints (source and target) of each edge. This method creates an EdgeSet, which does contains information about the endpoints, given a plain set of edges and the graph in which the edges are defined in.

      The returned set is a view of the given set and graph. Namely, its updated when the original set is updated and visa vera, and the endpoints in the EdgeSet will be up to date with the given graph.

      No validation is performed to ensure that all the given edges are actually in the given graph. If this is not the case, an exception may be thrown later when the graph is queried for an edge source and target.

      If g is IntGraph, a IEdgeSet is returned. In that case, prefer to pass IntSet as edges to avoid un/boxing, or use IEdgeSet.of(IntSet, IntGraph) instead.

      Usually an EdgeSet object is obtained via one of the method of a Graph, and rarely a user need to a create one, but it may be used to add multiple edges to a graph using the Graph.addEdges(EdgeSet) method. In the following snippet, a maximum cardinality matching is computed on a graph, and a new graph containing only the matching edges is created: 

       
 Graph<V, E> g = ...;
 Set<E> matching = MatchingAlgo.newInstance().computeMaximumMatching(g, null).edges();

 Graph<V,E> matchingGraph = Graph.newUndirected();
 matchingGraph.addVertices(g.vertices());
 matchingGraph.addEdges(EdgeSet.of(matching, g));
      Type Parameters:
      V - the vertices type
      E - the edges type
      Parameters:
      edges - a set of edges identifiers
      g - the graph in which the edges are defined in, and from which the endpoints of the edges should be retrieved
      Returns:
      an EdgeSet with the given edges, containing the endpoints information from the graph

    • allOf

      static <V, E> EdgeSet<V,E> allOf(Graph<V,E> g)
      Create an edge set object of all the edges in a graph.

      The edge set returned by Graph.edges() is a 'plain' set of edges, namely it is a set of the edge identifiers themselves but does not include any information about the endpoints (source and target) of each edge. This method creates an EdgeSet, which does contains information about the endpoints, of all the edges in a given graph.

      The returned set is a view of the given set and graph. Namely, its updated when the original set is updated and visa vera, and the endpoints in the EdgeSet will be up to date with the given graph.

      If g is IntGraph, a IEdgeSet is returned. In that case, prefer to pass IntSet as edges to avoid un/boxing, or use IEdgeSet.allOf(IntGraph) instead.

      Usually an EdgeSet object is obtained via one of the method of a Graph, and rarely a user need to a create one, but it may be used to add multiple edges to a graph using the Graph.addEdges(EdgeSet) method. In the following snippet, an auxillary graph is created which is a copy of an original graph g with additional vertex connected to all the original vertices, for shortest path potential function computation (used in Johnson APSP): 

       
 V auxillaryVertex = ...;
 Graph<V, E> auxillaryGraph = Graph.newDirected();
 auxillaryGraph.addVertices(g.vertices());
 auxillaryGraph.addVertex(auxillaryVertex);
 auxillaryGraph.addEdges(EdgeSet.allOf(g));
 for (V v : g.vertices())
 	auxillaryGraph.addEdge(auxillaryVertex, v, ...
      Type Parameters:
      V - the vertices type
      E - the edges type
      Parameters:
      g - a graph
      Returns:
      an EdgeSet of all the edges in the graph