I created a digraph using the jgrapht library. I use the successorListOf()
method to access a vertex's successor, but I'd like to be able to reach the n-th successor of a given vertex (which are Point objects in my case). My digraph has two branches (named B and C here). I made a simple and shorter code to make it easier:
public static DirectedGraph<Point, DefaultEdge> directedGraph = new DefaultDirectedGraph<Point, DefaultEdge>(DefaultEdge.class);
public static Point startPoint = new Point(2, 6, "S");
public static Point firstPoint = new Point(2, 7, "A");
public static Point secondPoint = new Point(2, 8, "B");
public static Point thirdPoint = new Point(2, 9, "B");
public static Point fourthPoint = new Point(2, 10, "B");
public static Point fifthPoint = new Point(3, 7, "C");
public static Point sixthPoint = new Point(4, 7, "C");
public static Point seventhPoint = new Point(5, 7, "C");
void setup () {
directedGraph.addVertex(startPoint);
directedGraph.addVertex(firstPoint);
directedGraph.addVertex(secondPoint);
directedGraph.addVertex(thirdPoint);
directedGraph.addVertex(fourthPoint);
directedGraph.addVertex(fifthPoint);
directedGraph.addVertex(sixthPoint);
directedGraph.addVertex(seventhPoint);
directedGraph.addEdge(startPoint, firstPoint);
directedGraph.addEdge(firstPoint, secondPoint);
directedGraph.addEdge(firstPoint, thirdPoint);
directedGraph.addEdge(firstPoint, fourthPoint);
}
// --------------------------------------------------------------
public static ArrayList<Point> pointList = new ArrayList<Point>();
public static class Point {
public int x;
public int y;
public String iD;
public Point(int x, int y, String iD)
{
this.x = x;
this.y = y;
this.iD= iD;
}
@Override
public String toString() {
return ("[x="+x+" y="+y+" iD="+iD+ "]");
}
@Override
public int hashCode() {
int hash = 7;
hash = 71 * hash + this.x;
hash = 71 * hash + this.y;
return hash;
}
@Override
public boolean equals(Object other)
{
if (this == other)
return true;
if (!(other instanceof Point))
return false;
Point otherPoint = (Point) other;
return otherPoint.x == x && otherPoint.y == y;
}
}
I'd like to add an edge between the firstPoint and each point of the "B" branch, and instead of having:
directedGraph.addEdge(firstPoint, secondPoint);
directedGraph.addEdge(firstPoint, thirdPoint);
directedGraph.addEdge(firstPoint, fourthPoint);
I'd like to use:
for (Point successor : Graphs.successorListOf (directedGraph, firstPoint)) {
if (successor.type.equals("B") {
directedGraph.addEdge(firstPoint, successor);
}
}
But here I can only reach the first successor of the branch B. How can I reach the successor of the successor etc, in the case of n-th successor ? The number of vertices in the B branch may change, that's why I'm looking for a way to do this automatically instead of Point by Point.
How could I do this ?
On the drawing,1 would be my startPoint, 2 would be my firstPoint, and then there are two branches which would be my B & C branches
I wrote the following code, but it's not tested and you might need to modify it to fit your requirements.
This code is running a DFS (depth first search) to a predefined depth using the variables and instances you used in your provided examples.
public void getSuccessor(DirectedGraph<Point, DefaultEdge> graph, Point point, String type, int depth) {
List<Point> visitedPoints = new ArrayList<>();
_getSuccessor(graph, point, visitedPoints, type, depth);
}
private void _getSuccessor(DirectedGraph<Point, DefaultEdge> graph, Point point, List<Point> visitedPoints, String type, int depth){
if(depth == 0)
return;
// Mark node as visited
visitedPoints.add(point);
// Loop on all its successors
for(Point successor : Graphs.successorListOf (directedGraph, point)){
// If node not already visited
if(!visitedPoints.contains(successor) && successor.type.equals(type)) {
directedGraph.addEdge(firstPoint, successor);
_getSuccessor(graph, successor, visitedPoints, type, depth-1);
}
}
}