hi,
I want to try DijkstraShortestPathFinder, I construct the graphic via a Esri
shape file. unfortunately I found the return of the pathfinder is always
"null", when i debug the code, I found the calulate()function always return
very quickly, since the DijkstraIterator.DijkstraNode.cost== Double.maxvalue is
true.
I don't know why , My code is as below, and the the attribute of the
shapefile includes "fid","fnode" "tonode" etc.., fnode and tnode uniquelly
specify a node, is the second(ft.getAttribute(2).toString().trim() in the code)
and the third attribute of a feature, thus I use those id as the hashkey.
Thanks a lot for your help.
Vicky
public class ShortPath24 {
public static void main(String argv[]){
try {
//read feature from shapefilestore
BasicLineGraphBuilder lgb = new BasicLineGraphBuilder();
ShapefileDataStore ds= new ShapefileDataStore(new
URL("file:///d:/temp/road/xuhui_polyline.shp"));
FeatureSource fs = (FeatureSource)ds.getFeatureSource("xuhui_polyline");
FeatureCollection fr = fs.getFeatures();
FeatureIterator f = fr.features();
Hashtable nodes = new Hashtable();
Hashtable edges = new Hashtable();
while(f.hasNext()){
//Add nodes and BasicLineGraphBuilder
org.geotools.feature.Feature ft = f.next();
MultiLineString a2=(MultiLineString)ft.getDefaultGeometry();
Coordinate[] coordi = a2.getCoordinates();
OptXYNode tempfromNode =new OptXYNode();
tempfromNode.setCoordinate(coordi[0]);
String key1=ft.getAttribute(2).toString().trim();
if (!nodes.containsKey(key1)){
lgb.addNode(tempfromNode);
nodes.put(key1, tempfromNode);
}
else
tempfromNode =(OptXYNode) nodes.get(key1);
OptXYNode temptoNode =new OptXYNode();
temptoNode.setCoordinate(coordi[coordi.length-1]);
String key2=ft.getAttribute(3).toString().trim();
if (!nodes.containsKey(key2)){
lgb.addNode(temptoNode);
nodes.put(key2, temptoNode);
}
else
temptoNode =(OptXYNode) nodes.get(key1);
Edge ed= new BasicEdge(tempfromNode, temptoNode);
addAnEdge(tempfromNode,ed);
addAnEdge(temptoNode,ed);
edges.put(ft.getAttribute(1).toString(), ed);
lgb.addEdge(ed);
}
Graph g = lgb.getGraph();
System.out.println(g.getNodes().size());
System.out.println(g.getEdges().size());
OptXYNode source=(OptXYNode) nodes.get("89059633400121");
OptXYNode dest= (OptXYNode)nodes.get("89059633300051");
System.out.println(dest);
DijkstraIterator.EdgeWeighter weighter = new
DijkstraIterator.EdgeWeighter() {
public double getWeight(Edge e) {
return 1.0; //constant
}
};
DijkstraShortestPathFinder pf = new DijkstraShortestPathFinder( g, source,
weighter);
pf.calculate();
Path path=pf.getPath(dest);
System.out.println(path);
}
catch (Exception e){
e.printStackTrace();
}
}
public static void addAnEdge(OptXYNode node,Edge e){
Edge array[]=node.getEdgeArray();
node.setDegree(node.getDegree()+1);
for (int i=0;i<array.length;i++)
node.add(array[i]);
node.add(e);
}
}
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