Examples of org.geotools.graph.structure.Graph

org.geotools.graph.structure.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. @see Node @see Edge @author Justin Deoliveira, Refractions Research Inc, jdeolive@refractions.net @source $URL$

        }
        return ret;
    }
    
    private static void showGraph(Collection nodes, Collection edges, int phase){
        Graph g = new BasicGraph(nodes, edges);
        javax.swing.JFrame frame = new javax.swing.JFrame();
        GraphViewer viewer = new GraphViewer();
        viewer.setGraph(g);
        frame.getContentPane().add(viewer);
        frame.setDefaultCloseOperation(javax.swing.JFrame.EXIT_ON_CLOSE);

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    assertTrue(n1.getDegree() == 2);
  }
    
  
  public void test_getGraph() {
    Graph graph = m_builder.getGraph();
    assertTrue(graph instanceof DirectedGraph);
  }

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        for (int i = 0; i < nodes.length; i++){
            System.out.println("triangulating node " + i);
            triangleList = insertNode(tempNodes[i], triangleList);
        }


        Graph g = triangleListToGraph(triangleList);
                
        return g;  
    }

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            if (!(nodesVisited.contains(next))){
                Vector componentNodes = new Vector();
                Vector componentEdges = new Vector();
                expandComponent(next, edges, componentNodes, componentEdges);
                nodesVisited.addAll(componentNodes);
                Graph component = new BasicGraph(componentNodes, componentEdges);
                components.add(component);
            }
        }
        
        return components;

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          new Coordinate(base.x + i, base.y + i)
        )
      );  
    }
    generator().generate();
    Graph built = generator().getGraph();
    
    //ensure correct graph structure
    assertTrue(built.getEdges().size() == n);
    assertTrue(built.getNodes().size() == n+1);
    
    assertTrue(built.getNodesOfDegree(1).size() == 2);
    assertTrue(built.getNodesOfDegree(2).size() == n-1);
    
    //ensure coordinates
    GraphVisitor visitor = new GraphVisitor() {
      public int visit(Graphable component) {
        Edge e = (Edge)component;
        XYNode a = (XYNode)e.getNodeA();
        XYNode b = (XYNode)e.getNodeB();
        
        //coordinats should be a distance of sqrt(2)
        assertTrue(
          Math.abs(a.getCoordinate().x - b.getCoordinate().x) == 1 &&
          Math.abs(a.getCoordinate().y - b.getCoordinate().y) == 1
        );
        
//        assertTrue(
//            Math.abs(a.getX() - b.getX()) == 1 
//         && Math.abs(a.getY() - b.getY()) == 1
//        );
        return(0);
      }
    };
    built.visitEdges(visitor);
  }

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    generator().add(
      new LineSegment(new Coordinate(base.x + n, base.y + n), base) 
    );
    
    generator().generate();
    Graph built = generator().getGraph();
    
    assertTrue(built.getEdges().size() == n+1);
    assertTrue(built.getNodes().size() == n+1);
    
    //all nodes should be of degree 2
    assertTrue(
      built.getNodesOfDegree(2).size() == built.getNodes().size()
    );
    
    //ensure coordinates
    GraphVisitor visitor = new GraphVisitor() {
      public int visit(Graphable component) {
        Edge e = (Edge)component;
        XYNode a = (XYNode)e.getNodeA();
        XYNode b = (XYNode)e.getNodeB();
        
        if (b.getCoordinate().equals(base)) {
          assertTrue(a.getCoordinate().equals(new Coordinate(n,n)));  
        } 
        else {
         assertTrue(
            Math.abs(a.getCoordinate().x - b.getCoordinate().x) == 1 &&
            Math.abs(a.getCoordinate().y - b.getCoordinate().y) == 1
          );
        }
    
        return(0);
      }
    };
    built.visitEdges(visitor);
  }

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        LineString lineString3 = gf.createLineString(new Coordinate[] { c7, c4 });
        gen.add(lineString);
        gen.add(lineString2);
        gen.add(lineString3);


        Graph graph = gen.getGraph();
        Collection graphNodes = graph.getNodes();
        assertEquals(5, graphNodes.size());
        Collection<Coordinate> graphNodeCoordinates = getCoordinates(graphNodes);
        assertTrue(graphNodeCoordinates.contains(c2));
        assertFalse("c6 should be snapped to c2", graphNodeCoordinates.contains(c6));
        assertTrue("c7 should not have been snapped to c2 - distance bigger than tolerance", graphNodeCoordinates.contains(c7)); //
        assertEquals(3, graph.getEdges().size());
    }

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      serializer().setProperty(SerializedReaderWriter.FILENAME, victim.getAbsolutePath());
      
      serializer().write(builder().getGraph());
      
      Graph before = builder().getGraph();
      Graph after = serializer().read();
      
      //ensure same number of nodes and edges
      assertTrue(before.getNodes().size() == after.getNodes().size());
      assertTrue(before.getEdges().size() == after.getEdges().size());
      
      //ensure same graph structure
      GraphVisitor visitor = new GraphVisitor() {
        public int visit(Graphable component) {
          DirectedEdge e = (DirectedEdge)component;
          
          assertTrue(e.getInNode().getID() == e.getID());
          assertTrue(e.getOutNode().getID() == e.getID()+1);
          
          return(0);
        }
      };
      after.visitEdges(visitor);
      
      visitor = new GraphVisitor() {
        public int visit(Graphable component) {
          DirectedNode n = (DirectedNode)component;
          
          if (n.getDegree() == 1) {
            assertTrue(n.getID() == 0 || n.getID() == nnodes-1);  
          }
          else {
            assertTrue(n.getDegree() == 2);
            
            Edge in = (Edge)n.getInEdges().get(0);
            Edge out = (Edge)n.getOutEdges().get(0);
            
            assertTrue(
              (in.getID() == n.getID()-1 && out.getID() == n.getID())
            );
            
          }
          
          return(0);
        }
      };
      after.visitNodes(visitor);
      
    }
    catch(Exception e) {
      e.printStackTrace();
      assertTrue(false);

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      serializer().setProperty(SerializedReaderWriter.FILENAME, victim.getAbsolutePath());
      
      serializer().write(builder().getGraph());
      
      Graph before = builder().getGraph();
      Graph after = serializer().read();
      
      //ensure same number of nodes and edges
      assertTrue(before.getNodes().size() == after.getNodes().size());
      assertTrue(before.getEdges().size() == after.getEdges().size());
      
      //ensure same structure
      GraphVisitor visitor = new GraphVisitor() {
        public int visit(Graphable component) {
          DirectedNode n = (DirectedNode)component;
          String id = (String)n.getObject();
          
          assertTrue(obj2node.get(id) != null);
          
          StringTokenizer st = new StringTokenizer(id, ".");
          
          if (st.countTokens() == 1) {
            //root
            assertTrue(n.getDegree() == 2); 
            
            Node n0 = ((Edge)n.getEdges().get(0)).getOtherNode(n);
            Node n1 = ((Edge)n.getEdges().get(1)).getOtherNode(n);
            
            assertTrue(
              n0.getObject().equals("0.0") && n1.getObject().equals("0.1")
           || n0.getObject().equals("0.1") && n1.getObject().equals("0.0")
            );
          }
          else if (st.countTokens() == k+1) {
            //leaf
            assertTrue(n.getDegree() == 1);
            
            Node parent = ((DirectedEdge)n.getInEdges().get(0)).getInNode();
            String parentid = (String)parent.getObject();
            
            assertTrue(parentid.equals(id.substring(0, id.length()-2)));   
          } 
          else {
            //internal
            assertTrue(n.getDegree() == 3);
            
            String parent = ((DirectedEdge)n.getInEdges().get(0)).getInNode()
                              .getObject().toString();
            String c0 = ((DirectedEdge)n.getOutEdges().get(0)).getOutNode()
                              .getObject().toString();                      
            String c1 = ((DirectedEdge)n.getOutEdges().get(1)).getOutNode()
                              .getObject().toString();                      
                                              
            String parentid = id.substring(0, id.length()-2);
            
            assertTrue(
             parent.equals(parentid) && c0.equals(id+".0") && c1.equals(id+".1")
          || parent.equals(parentid) && c1.equals(id+".0") && c0.equals(id+".1")
            );
          }  
          
          return(0);
        }
      };
      after.visitNodes(visitor);
      
    }
    catch(Exception e) {
      e.printStackTrace();
      assertTrue(false);

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      serializer().setProperty(SerializedReaderWriter.FILENAME, victim.getAbsolutePath());
      
      serializer().write(builder().getGraph());
      
      Graph before = builder().getGraph();
      Graph after = serializer().read();
      
      //ensure same number of nodes and edges
      assertTrue(before.getNodes().size() == after.getNodes().size());
      assertTrue(before.getEdges().size() == after.getEdges().size());
      
      GraphVisitor visitor = new GraphVisitor() {
        public int visit(Graphable component) {
          Node n = (Node)component;
          if (n.getID() == 0 || n.getID() == nnodes-1) 
            assertTrue(n.getDegree() == 0);
          else if (n.getID() == 1 || n.getID() == nnodes-2)
            assertTrue(n.getDegree() == 1);
          else assertTrue(n.getDegree() == 2); 
           
          return(0); 
        }
      };
      after.visitNodes(visitor);
    }
    catch(Exception e) {
      e.printStackTrace();
      assertTrue(false); 
    }

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Related Classes of org.geotools.graph.structure.Graph

org.geotools.graph.build.basic.BasicDirectedGraphBuilderTest

org.geotools.graph.build.basic.BasicGraphBuilderTest

org.geotools.graph.build.line.LineStringGraphGeneratorTest

org.geotools.graph.build.opt.OptDirectedGraphBuilderTest

org.geotools.graph.build.opt.OptGraphBuilderTest

org.geotools.graph.build.polygon.PolygonGraphGeneratorTest

org.geotools.graph.GraphExamples

org.geotools.graph.io.standard.BasicGraphSerializerTest

org.geotools.graph.io.standard.DirectedGraphSerializerTest

org.geotools.graph.io.standard.OptDirectedGraphSerializerTest

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