structure5
Class GraphListDirected<V,E>

java.lang.Object
  extended by structure5.AbstractStructure<V>
      extended by structure5.GraphList<V,E>
          extended by structure5.GraphListDirected<V,E>
All Implemented Interfaces:
Iterable<V>, Graph<V,E>, Structure<V>

public class GraphListDirected<V,E>
extends GraphList<V,E>

A GraphListDirected is a list-based graph representation that consists of a collection of vertices and directed edges. Portions of the graph may be marked visited to support iterative algorithms. Iteration is provided over vertices, edges, and vertices adjacent to a particular vertex.

Example Usage:

To create a graph representation of the movie theaters nearest the Williams College Department of Computer Science's unix laboratory, and to print these theaters out in order of increasing distance, we could use the following:

  public static void main(String[] argv){
        Graph theaters = new GraphListDirected();
        FibHeap heap = new FibHeap();
        
        //instantiate array of locations 
        String[] locations = new String[]{"TCL 312", "Images Cinema", 
                                          "Movie Plex 3", "Cinema 1,2,&3", 
                                          "Cinema 7", "Berkshire Mall Cinemas"
                                          ,"Hathaway's Drive Inn Theatre",
                                          "Hollywood Drive-In Theatre"};

        //instantiate array of distances between location[0] 
        //and movie theaters
        double[] distances =  new double[]{-1, 0.0, 12.6, 12.9, 12.9, 
                                           14.7, 16.5, 18.0};
        
        //build graph
        for(int i=0; i < locations.length; i++) theaters.add(locations[i]);
        for(int i=1; i < distances.length; i++){
          theaters.addEdge(locations[0],locations[i],new Double(distances[i]));
        }
        
        //place neighbors of lab in into priority queue
        for(Iterator i=theaters.neighbors(locations[0]); i.hasNext();){
            Object theater = i.next();
            Object distance = theaters.getEdge(locations[0], theater).label();
            heap.add(new ComparableAssociation((Comparable)distance,theater));
        }
        
        //print out theaters in order of distance
        while(!heap.isEmpty()){
            ComparableAssociation show = (ComparableAssociation)heap.remove();
            System.out.println(show.getValue()+" is "+show.getKey()+" miles away.");
        }
  }
 

See Also:
GraphList, GraphListUndirected, GraphMatrixDirected

Constructor Summary
GraphListDirected()
          Construct a directed, adjacency-list based graph.
 
Method Summary
 void addEdge(V vLabel1, V vLabel2, E label)
          Add an edge between two vertices within the graph.
 int edgeCount()
          Determine the number of edges in graph.
 V remove(V label)
          Remove a vertex from the graph.
 E removeEdge(V vLabel1, V vLabel2)
          Remove possible edge between vertices labeled vLabel1 and vLabel2.
 String toString()
          Construct a string representation of graph.
 
Methods inherited from class structure5.GraphList
add, clear, contains, containsEdge, degree, edges, get, getEdge, isDirected, isEmpty, isVisited, isVisitedEdge, iterator, main, neighbors, reset, size, visit, visitEdge
 
Methods inherited from class structure5.AbstractStructure
elements, hashCode, values
 
Methods inherited from class java.lang.Object
equals, getClass, notify, notifyAll, wait, wait, wait
 
Methods inherited from interface structure5.Structure
elements, values
 

Constructor Detail

GraphListDirected

public GraphListDirected()
Construct a directed, adjacency-list based graph.

Method Detail

addEdge

public void addEdge(V vLabel1,
                    V vLabel2,
                    E label)
Add an edge between two vertices within the graph. Edge is directed. Duplicate edges are silently replaced. Labels on edges may be null.

Specified by:
addEdge in interface Graph<V,E>
Specified by:
addEdge in class GraphList<V,E>
Parameters:
vLabel1 - Source vertex.
vLabel2 - Destination vertex.
label - Label associated with the edge.

remove

public V remove(V label)
Remove a vertex from the graph. Associated edges are also removed. Non-vertices are silently ignored.

Specified by:
remove in interface Graph<V,E>
Specified by:
remove in interface Structure<V>
Specified by:
remove in class GraphList<V,E>
Parameters:
label - The label of the vertex within the graph.
Returns:
The label associated with the vertex.

removeEdge

public E removeEdge(V vLabel1,
                    V vLabel2)
Remove possible edge between vertices labeled vLabel1 and vLabel2. vLabel1 is the source.

Specified by:
removeEdge in interface Graph<V,E>
Specified by:
removeEdge in class GraphList<V,E>
Parameters:
vLabel1 - Source vertex.
vLabel2 - Destination vertex.
Returns:
The label associated with the edge removed.

edgeCount

public int edgeCount()
Determine the number of edges in graph.

Specified by:
edgeCount in interface Graph<V,E>
Specified by:
edgeCount in class GraphList<V,E>
Returns:
Number of edges in graph.

toString

public String toString()
Construct a string representation of graph.

Overrides:
toString in class Object
Returns:
String representing graph.