com.vividsolutions.jts.planargraph

Class PlanarGraph

Known Direct Subclasses:
LineMergeGraph

public abstract class PlanarGraph
extends java.lang.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 Summary

protected Set
dirEdges
protected Set
edges
protected NodeMap
nodeMap

Constructor Summary

PlanarGraph()
Constructs a empty graph.

Method Summary

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.
protected void
add(Edge edge)
Adds the Edge and its DirectedEdges with this PlanarGraph.
protected void
add(Node node)
Adds a node to the map, replacing any that is already at that location.
boolean
contains(DirectedEdge de)
Tests whether this graph contains the given DirectedEdge
boolean
contains(Edge e)
Tests whether this graph contains the given Edge
Iterator
dirEdgeIterator()
Returns an Iterator over the DirectedEdges in this PlanarGraph, in the order in which they were added.
Iterator
edgeIterator()
Returns an Iterator over the Edges in this PlanarGraph, in the order in which they were added.
Node
findNode(Coordinate pt)
Returns the Node at the given location, or null if no Node was there.
List
findNodesOfDegree(int degree)
Returns all Nodes with the given number of Edges around it.
Collection
getEdges()
Returns the Edges that have been added to this PlanarGraph
Collection
getNodes()
Iterator
nodeIterator()
Returns an Iterator over the Nodes in this PlanarGraph.
void
remove(DirectedEdge de)
Removes DirectedEdge from its from-Node and from this PlanarGraph.
void
remove(Edge edge)
Removes an Edge and its associated DirectedEdges from their from-Nodes and from the graph.
void
remove(Node node)
Removes a node from the graph, along with any associated DirectedEdges and Edges.

Field Details

dirEdges

protected Set dirEdges

edges

protected Set edges

nodeMap

protected NodeMap nodeMap

Constructor Details

PlanarGraph

public PlanarGraph()
Constructs a empty graph.

Method Details

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.

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(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.

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

contains

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

dirEdgeIterator

public Iterator dirEdgeIterator()
Returns an Iterator over the DirectedEdges in this PlanarGraph, in the order in which they were added.

edgeIterator

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

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

findNodesOfDegree

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

getEdges

public Collection getEdges()
Returns the Edges that have been added to this PlanarGraph

getNodes

public Collection getNodes()

nodeIterator

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

remove

public void remove(DirectedEdge de)
Removes DirectedEdge from its from-Node and from this PlanarGraph. 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(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(Node node)
Removes a node from the graph, along with any associated DirectedEdges and Edges.