Package org.locationtech.jts.planargraph

Class PlanarGraph

  • Direct Known Subclasses:
    LineMergeGraph
    public abstract class PlanarGraph
extends Object
    Represents a directed graph which is embeddable in a planar surface.

    This class and the other classes in this package serve as a framework for building planar graphs for specific algorithms. This class must be subclassed to expose appropriate methods to construct the graph. This allows controlling the types of graph components (DirectedEdges, Edges and Nodes) which can be added to the graph. An application which uses the graph framework will almost always provide subclasses for one or more graph components, which hold application-specific data and graph algorithms.

    Version:
    1.7

    • Field Detail

      • edges

        protected Set edges

      • dirEdges

        protected Set dirEdges

      • nodeMap

        protected NodeMap nodeMap

    • Constructor Detail

      • PlanarGraph

        public PlanarGraph()
        Constructs a empty graph.

    • Method Detail

      • findNode

        public Node findNode​(Coordinate pt)
        Returns the Node at the given location, or null if no Node was there.
        Parameters:
        pt - the location to query
        Returns:
        the node found or null if this graph contains no node at the location

      • add

        protected void add​(Node node)
        Adds a node to the map, replacing any that is already at that location. Only subclasses can add Nodes, to ensure Nodes are of the right type.
        Parameters:
        node - the node to add

      • add

        protected void add​(Edge edge)
        Adds the Edge and its DirectedEdges with this PlanarGraph. Assumes that the Edge has already been created with its associated DirectEdges. Only subclasses can add Edges, to ensure the edges added are of the right class.

      • add

        protected void add​(DirectedEdge dirEdge)
        Adds the Edge to this PlanarGraph; only subclasses can add DirectedEdges, to ensure the edges added are of the right class.

      • nodeIterator

        public Iterator nodeIterator()
        Returns an Iterator over the Nodes in this PlanarGraph.

      • contains

        public boolean contains​(Edge e)
        Tests whether this graph contains the given Edge
        Parameters:
        e - the edge to query
        Returns:
        true if the graph contains the edge

      • contains

        public boolean contains​(DirectedEdge de)
        Tests whether this graph contains the given DirectedEdge
        Parameters:
        de - the directed edge to query
        Returns:
        true if the graph contains the directed edge

      • dirEdgeIterator

        public Iterator dirEdgeIterator()
        Returns an Iterator over the DirectedEdges in this PlanarGraph, in the order in which they were added.
        See Also:
        add(Edge), add(DirectedEdge)

      • edgeIterator

        public Iterator edgeIterator()
        Returns an Iterator over the Edges in this PlanarGraph, in the order in which they were added.
        See Also:
        add(Edge)

      • getEdges

        public Collection getEdges()
        Returns the Edges that have been added to this PlanarGraph
        See Also:
        add(Edge)

      • remove

        public void remove​(Edge edge)
        Removes an Edge and its associated DirectedEdges from their from-Nodes and from the graph. Note: This method does not remove the Nodes associated with the Edge, even if the removal of the Edge reduces the degree of a Node to zero.

      • remove

        public void remove​(DirectedEdge de)
        Removes a DirectedEdge from its from-Node and from this graph. This method does not remove the Nodes associated with the DirectedEdge, even if the removal of the DirectedEdge reduces the degree of a Node to zero.

      • remove

        public void remove​(Node node)
        Removes a node from the graph, along with any associated DirectedEdges and Edges.

      • findNodesOfDegree

        public List findNodesOfDegree​(int degree)
        Returns all Nodes with the given number of Edges around it.