Package com.jgalgo

Interface WeightFunction.Int

  • All Superinterfaces:
    Comparator<Integer>, it.unimi.dsi.fastutil.ints.IntComparator, WeightFunction
    All Known Subinterfaces:
    Weights.Byte, Weights.Int, Weights.Short
    Enclosing interface:
    WeightFunction
    Functional Interface:
    This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.
    @FunctionalInterface
public static interface WeightFunction.Int
extends WeightFunction
    Weight function that maps graph edges (or vertices) to integer weights.

    Some algorithms implementations support only integers weights, or run faster in such a case. This interface is the API for these algorithms for the edges (or vertices) integer weights. 

     
 // Create a directed graph with three vertices and edges between them
 Graph g = Graph.newBuilderDirected().build();
 int v1 = g.addVertex();
 int v2 = g.addVertex();
 int v3 = g.addVertex();
 int e1 = g.addEdge(v1, v2);
 int e2 = g.addEdge(v2, v3);
 int e3 = g.addEdge(v1, v3);

 // Assign some weights to the edges
 Weights.Int weights = g.addEdgesWeights("weightsKey", int.class);
 weights.set(e1, 1);
 weights.set(e2, 3);
 weights.set(e3, 15);
 EdgeWeightFunc.Int weightFunc = weights;

 // Calculate the shortest paths from v1 to all other vertices
 ShortestPathSingleSource ssspAlgo = ShortestPathSingleSource.newBuilder().setIntWeights(true).build();
 ShortestPathSingleSource.Result ssspRes = ssspAlgo.computeShortestPaths(g, weightFunc, v1);

 // Print the shortest path from v1 to v3
 assert ssspRes.distance(v3) == 4;
 assert ssspRes.getPath(v3).equals(IntList.of(e1, e2));
 System.out.println("Distance from v1 to v3 is: " + ssspRes.distance(v3));
 System.out.println("The shortest path from v1 to v3 is:");
 for (int e : ssspRes.getPath(v3)) {
 	int u = g.edgeSource(e), v = g.edgeTarget(e);
 	System.out.println(" " + e + "(" + u + ", " + v + ")");
 }
    Author:
    Barak Ugav

    • Method Detail

      • weight

        @Deprecated
default double weight​(int element)
        Deprecated.
        Description copied from interface: WeightFunction
        Get the weight of an element.
        Specified by:
        weight in interface WeightFunction
        Parameters:
        element - an element identifier
        Returns:
        the weight of the element

      • weightInt

        int weightInt​(int element)
        Get the integer weight of an element.
        Parameters:
        element - an element identifier
        Returns:
        the integer weight of the element
        Throws:
        IndexOutOfBoundsException - if element is not a valid element identifier

      • compare

        default int compare​(int e1,
                    int e2)
        Description copied from interface: WeightFunction
        Compare two elements by their weights.
        Specified by:
        compare in interface it.unimi.dsi.fastutil.ints.IntComparator
        Specified by:
        compare in interface WeightFunction