[jgrapht-users] "graph must contain the start vertex" when running KShortestPaths

[Sebastian M. <woo...@gm...>]

Hello,

sorry this is such a long mail, but I included a test program, and my 
graph is quite large.

I am using JGraphT to create graphs of my data with great success so 
far. However, now I am trying to calculate the shortest paths between 
two nodes using KShortestPaths, and I only receive the following exception:

[code]
java.lang.IllegalArgumentException: graph must contain the start vertex
     at 
org.jgrapht.traverse.CrossComponentIterator.<init>(CrossComponentIterator.java:170)
     at 
org.jgrapht.traverse.BreadthFirstIterator.<init>(BreadthFirstIterator.java:92)
     at 
org.jgrapht.alg.ConnectivityInspector.connectedSetOf(ConnectivityInspector.java:142)
     at 
org.jgrapht.alg.ConnectivityInspector.pathExists(ConnectivityInspector.java:208)
     at 
org.jgrapht.alg.RankingPathElementList.isGuardVertexDisconnected(RankingPathElementList.java:347)
     at 
org.jgrapht.alg.RankingPathElementList.isNotValidPath(RankingPathElementList.java:364)
     at 
org.jgrapht.alg.RankingPathElementList.addPathElements(RankingPathElementList.java:203)
     at 
org.jgrapht.alg.KShortestPathsIterator.tryToAddNewPaths(KShortestPathsIterator.java:361)
     at 
org.jgrapht.alg.KShortestPathsIterator.updateOutgoingVertices(KShortestPathsIterator.java:398)
     at 
org.jgrapht.alg.KShortestPathsIterator.next(KShortestPathsIterator.java:177)
     at org.jgrapht.alg.KShortestPaths.getPaths(KShortestPaths.java:150)
     at KShortestPathsMain.main(KShortestPathsMain.java:97)
[/code]

Note that I am only getting this exception with that one, large graph I 
created from my data. When I create a graph by hand, it does not occur. 
Here is my test program. The graph is attached.

[code]
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.List;

import org.jgrapht.GraphPath;
import org.jgrapht.alg.KShortestPaths;
import org.jgrapht.graph.DefaultWeightedEdge;
import org.jgrapht.graph.SimpleWeightedGraph;

public class KShortestPathsMain {

     public KShortestPathsMain() {}

     public static void main(String[] args) {

         SimpleWeightedGraph<String, DefaultWeightedEdge> graph = new 
SimpleWeightedGraph<>(DefaultWeightedEdge.class);

             FileReader fstream = null;
             try {
                 fstream = new FileReader("edges.txt");
             } catch (FileNotFoundException e1) {
                 e1.printStackTrace();
             }
             BufferedReader in = new BufferedReader(fstream);

             String[] edgeText;
             DefaultWeightedEdge ed;
             String line = null;
             try {
                 line = in.readLine();
             } catch (IOException e1) {
                 // TODO Auto-generated catch block
                 e1.printStackTrace();
             }
             while(line != null) {
                 edgeText = line.split("\t");

                 graph.addVertex(edgeText[0]);
                 graph.addVertex(edgeText[1]);
                 ed = graph.addEdge(edgeText[0], edgeText[1]);
                 graph.setEdgeWeight(ed, Double.parseDouble(edgeText[2]));

                 try {
                     line = in.readLine();
                 } catch (IOException e) {
                     e.printStackTrace();
                 }
             }

             // Close the input stream
             try {
                 in.close();
             } catch (IOException e1) {
                 e1.printStackTrace();
             }

         DefaultWeightedEdge src = graph.getEdge("M013", "M014");

         KShortestPaths<String, DefaultWeightedEdge> kPaths = new 
KShortestPaths<String, DefaultWeightedEdge>(
                 graph, graph.getEdgeSource(src), 5);
         List<GraphPath<String,DefaultWeightedEdge>> paths = null;

         try {
             paths = kPaths.getPaths(graph.getEdgeTarget(src));
             for (GraphPath<String, DefaultWeightedEdge> path : paths) {
                 for (DefaultWeightedEdge edge : path.getEdgeList()) {
                     System.out.print("<" + graph.getEdgeSource(edge) + "\t"
                             + graph.getEdgeTarget(edge) + "\t" + edge + 
">\t");
                 }
                 System.out.println(": " + path.getWeight());
             }
         } catch (IllegalArgumentException e) {
             e.printStackTrace();
         }
     }
}

[/code]

I tried different edges, and directed and undirected graphs. Same 
result. If anyone has a clue what might be going on here, I'd very much 
appreciate help.


Sebastian