Package org._3pq.jgrapht.graph

Class AsUndirectedGraph

  • All Implemented Interfaces:
    java.io.Serializable, Graph, UndirectedGraph
    public class AsUndirectedGraph
extends GraphDelegator
implements java.io.Serializable, UndirectedGraph
    An undirected view of the backing directed graph specified in the constructor. This graph allows modules to apply algorithms designed for undirected graphs to a directed graph by simply ignoring edge direction. If the backing directed graph is an oriented graph, then the view will be a simple graph; otherwise, it will be a multigraph. Query operations on this graph "read through" to the backing graph. Attempts to add edges will result in an UnsupportedOperationException, but vertex addition/removal and edge removal are all supported (and immediately reflected in the backing graph).

    Note that edges returned by this graph's accessors are really just the edges of the underlying directed graph. Since there is no interface distinction between directed and undirected edges, this detail should be irrelevant to algorithms.

    This graph does not pass the hashCode and equals operations through to the backing graph, but relies on Object's equals and hashCode methods. This graph will be serializable if the backing graph is serializable.

    Since:
    Aug 14, 2003
    Author:
    John V. Sichi
    See Also:
    Serialized Form

    • Constructor Detail

      • AsUndirectedGraph

        public AsUndirectedGraph​(DirectedGraph g)
        Constructor for AsUndirectedGraph.
        Parameters:
        g - the backing directed graph over which an undirected view is to be created.

    • Method Detail

      • getAllEdges

        public java.util.List getAllEdges​(java.lang.Object sourceVertex,
                                  java.lang.Object targetVertex)
        Description copied from interface: Graph
        Returns a list of all edges connecting source vertex to target vertex if such vertices exist in this graph. If any of the vertices does not exist or is null, returns null. If both vertices exist but no edges found, returns an empty list.

        In undirected graphs, some of the returned edges may have their source and target vertices in the opposite order. In simple graphs the returned list is either singleton list or empty list.

        Specified by:
        getAllEdges in interface Graph
        Overrides:
        getAllEdges in class GraphDelegator
        Parameters:
        sourceVertex - source vertex of the edge.
        targetVertex - target vertex of the edge.
        Returns:
        a list of all edges connecting source vertex to target vertex.
        See Also:
        Graph.getAllEdges(Object, Object)

      • getEdge

        public Edge getEdge​(java.lang.Object sourceVertex,
                    java.lang.Object targetVertex)
        Description copied from interface: Graph
        Returns an edge connecting source vertex to target vertex if such vertices and such edge exist in this graph. Otherwise returns null. If any of the specified vertices is null returns null

        In undirected graphs, the returned edge may have its source and target vertices in the opposite order.

        Specified by:
        getEdge in interface Graph
        Overrides:
        getEdge in class GraphDelegator
        Parameters:
        sourceVertex - source vertex of the edge.
        targetVertex - target vertex of the edge.
        Returns:
        an edge connecting source vertex to target vertex.
        See Also:
        Graph.getEdge(Object, Object)

      • addAllEdges

        public boolean addAllEdges​(java.util.Collection edges)
        Description copied from interface: Graph
        Adds all of the specified edges to this graph. The behavior of this operation is undefined if the specified vertex collection is modified while the operation is in progress. This method will invoke the Graph.addEdge(Edge) method.
        Specified by:
        addAllEdges in interface Graph
        Overrides:
        addAllEdges in class AbstractGraph
        Parameters:
        edges - the edges to be added to this graph.
        Returns:
        true if this graph changed as a result of the call
        See Also:
        Graph.addAllEdges(Collection)

      • addEdge

        public boolean addEdge​(Edge e)
        Description copied from interface: Graph
        Adds the specified edge to this graph. More formally, adds the specified edge, e, to this graph if this graph contains no edge e2 such that e2.equals(e). If this graph already contains such edge, the call leaves this graph unchanged and returns false. If the edge was added to the graph, returns true.

        Some graphs do not allow edge-multiplicity. In such cases, if the graph already contains an edge going from e.getSource() vertex to e.getTarget() vertex, than this method does not change the graph and returns false.

        The source and target vertices of the specified edge must already be in this graph. If this is not the case, IllegalArgumentException is thrown. The edge must also be assignment compatible with the class of the edges produced by the edge factory of this graph. If this is not the case ClassCastException is thrown.

        Specified by:
        addEdge in interface Graph
        Overrides:
        addEdge in class GraphDelegator
        Parameters:
        e - edge to be added to this graph.
        Returns:
        true if this graph did not already contain the specified edge.
        See Also:
        Graph.addEdge(Edge)

      • addEdge

        public Edge addEdge​(java.lang.Object sourceVertex,
                    java.lang.Object targetVertex)
        Description copied from interface: Graph
        Creates a new edge in this graph, going from the source vertex to the target vertex, and returns the created edge. Some graphs do not allow edge-multiplicity. In such cases, if the graph already contains an edge from the specified source to the specified target, than this method does not change the graph and returns null.

        The source and target vertices must already be contained in this graph. If they are not found in graph IllegalArgumentException is thrown.

        This method creates the new edge e using this graph's EdgeFactory. For the new edge to be added e must not be equal to any other edge the graph (even if the graph allows edge-multiplicity). More formally, the graph must not contain any edge e2 such that e2.equals(e). If such e2 is found then the newly created edge e is abandoned, the method leaves this graph unchanged returns null.

        Specified by:
        addEdge in interface Graph
        Overrides:
        addEdge in class GraphDelegator
        Parameters:
        sourceVertex - source vertex of the edge.
        targetVertex - target vertex of the edge.
        Returns:
        The newly created edge if added to the graph, otherwise null.
        See Also:
        Graph.addEdge(Object, Object)

      • degreeOf

        public int degreeOf​(java.lang.Object vertex)
        Description copied from interface: UndirectedGraph
        Returns the degree of the specified vertex. A degree of a vertex in an undirected graph is the number of edges touching that vertex.
        Specified by:
        degreeOf in interface UndirectedGraph
        Overrides:
        degreeOf in class GraphDelegator
        Parameters:
        vertex - vertex whose degree is to be calculated.
        Returns:
        the degree of the specified vertex.
        See Also:
        UndirectedGraph.degreeOf(Object)

      • toString

        public java.lang.String toString()
        Description copied from class: AbstractGraph
        Returns a string of the parenthesized pair (V, E) representing this G=(V,E) graph. 'V' is the string representation of the vertex set, and 'E' is the string representation of the edge set.
        Overrides:
        toString in class GraphDelegator
        Returns:
        a string representation of this graph.
        See Also:
        AbstractGraph.toString()