Package org.geotools.graph.structure

Interface Graph

All Known Subinterfaces:
DirectedGraph
All Known Implementing Classes:
BasicDirectedGraph, BasicGraph
public interface Graph
Represents a graph.

A graph is a collection of nodes (verticies) connected by links called edges (arcs).

In most applications nodes of a graph represent the objects being modelled, and the edges represent the relationships between the objects. An example could be a polygon coverage in which one wishes to model a boundary sharing relationship. The following is an illustration.



In the above figure, the objects (nodes) are the polygons themselves, and the relationship (edges) between them is boundary sharing.

However, there exists types of graphs in which the roles are reversed and the edges are the objects, and the nodes are the relationships. An example of such a graph is the stream network shown below.



In the above figure, the objects (edges) are the stream segments and the relationship (nodes) between them is endpoint sharing. However, if desirable one could model the second case similar to the first. The resulting graph is shown below.



The Graph object is intended to serve as a container for a collection of nodes and edges. It does dont define or manage the relationship among the components it contains.

Author:
Justin Deoliveira, Refractions Research Inc, jdeolive@refractions.net
See Also:

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    static final int
    FAIL_QUERY
    Signal to indicate that a graph component does NOT meet the requirements of a query made against the graph.
    static final int
    PASS_AND_CONTINUE
    Signal to indicate that a graph component meets the requirements of a query against a graph and that the query should continue.
    static final int
    PASS_AND_STOP
    Signal to indicate that a graph component meets the requirements of a query against a graph and that the query should end.

  • Method Summary

    Modifier and Type
    Method
    Description
    Collection<Edge>
    getEdges()
    Returns the edges of the graph.
    Collection<Node>
    getNodes()
    Returns the nodes of the graph.
    List<Node>
    getNodesOfDegree(int n)
    Returns all the nodes in the graph of a specified degree.
    List<Edge>
    getVisitedEdges(boolean visited)
    Returns all the edges in the graph that have been marked as visited or non-visited.
    List<Node>
    getVisitedNodes(boolean visited)
    Returns all the nodes in the graph that have been marked as visited or non-visited.
    List<? extends Graphable>
    queryEdges(GraphVisitor visitor)
    Performs a query against the edges of the graph.
    List<Node>
    queryNodes(GraphVisitor visitor)
    Performs a query against the nodes of the graph.
    void
    visitEdges(GraphVisitor visitor)
    Applies the visitor pattern to the edges of the graph.
    void
    visitNodes(GraphVisitor visitor)
    Applies the visitor pattern to the nodes of the graph.

  • Field Details

    • PASS_AND_CONTINUE

      static final int PASS_AND_CONTINUE
      Signal to indicate that a graph component meets the requirements of a query against a graph and that the query should continue.
      See Also:

    • PASS_AND_STOP

      static final int PASS_AND_STOP
      Signal to indicate that a graph component meets the requirements of a query against a graph and that the query should end.
      See Also:

    • FAIL_QUERY

      static final int FAIL_QUERY
      Signal to indicate that a graph component does NOT meet the requirements of a query made against the graph.
      See Also:

  • Method Details

    • getNodes

      Collection<Node> getNodes()
      Returns the nodes of the graph.
      Returns:
      A collection of Node objects.
      See Also:

    • getEdges

      Collection<Edge> getEdges()
      Returns the edges of the graph.
      Returns:
      A collection of Edge objects.
      See Also:

    • queryNodes

      List<Node> queryNodes(GraphVisitor visitor)
      Performs a query against the nodes of the graph. Each Node object contained in the graph is passed to a GraphVisitor to determine if it meets the query criteria.
      Parameters:
      visitor - Determines if node meets query criteria. Returns MEET_AND_CONTINUE to signal that the node meets the query criteria and the query should continue.
      Returns MEET_AND_STOP to signal that the node meest the query criteria and the query should stop.
      FAIL_QUERY to signal that the node does NOT meet the query criteria.
      Returns:
      A collection of nodes that meet the query criteria.
      See Also:

    • queryEdges

      List<? extends Graphable> queryEdges(GraphVisitor visitor)
      Performs a query against the edges of the graph. Each Edge object contained in the graph is passed to a GraphVisitor to determine if it meets the query criteria.
      Parameters:
      visitor - Determines if the meets the query criteria.
      Returns MEET_AND_CONTINUE to signal that the edge meets the query criteria and the query should continue.
      Returns MEET_AND_STOP to signal that the edge meest the query criteria and the query should stop.
      FAIL_QUERY to signal that the edge does NOT meet the query criteria.
      Returns:
      A collection of edges that meet the query criteria.
      See Also:

    • visitNodes

      void visitNodes(GraphVisitor visitor)
      Applies the visitor pattern to the nodes of the graph.

    • visitEdges

      void visitEdges(GraphVisitor visitor)
      Applies the visitor pattern to the edges of the graph.

    • getNodesOfDegree

      List<Node> getNodesOfDegree(int n)
      Returns all the nodes in the graph of a specified degree. The degree of a node is the number of edges that are adjacent to the node.
      Parameters:
      n - The desired degree of nodes to be returned.
      Returns:
      A collection of nodes of degree n.
      See Also:

    • getVisitedNodes

      List<Node> getVisitedNodes(boolean visited)
      Returns all the nodes in the graph that have been marked as visited or non-visited.
      Parameters:
      visited - True if node is visited, false if node is unvisited.
      Returns:
      List of nodes marked as visited / non-visited.
      See Also:

    • getVisitedEdges

      List<Edge> getVisitedEdges(boolean visited)
      Returns all the edges in the graph that have been marked as visited or non-visited.
      Parameters:
      visited - True if edge is visited, false if edge is unvisited.
      Returns:
      List of edges marked as visited / non-visited.
      See Also: