Examples with HashSet chapter3.section5.HashSet used on opensource projects

Example 6 with HashSet

use of chapter3.section5.HashSet in project algorithms-sedgewick-wayne by reneargento.

the class Exercise51_RealWorldDAG method randomRealDAG.

private Digraph randomRealDAG(int randomVerticesToChoose, int randomEdgesToChoose) {
    String filePath = Constants.FILES_PATH + Constants.CITATION_DIGRAPH_FILE;
    String separator = " ";
    In in = new In(filePath);
    Digraph fullDigraph = new Digraph();
    SeparateChainingHashTable<Integer, Integer> realDAGToFullDAGMap = new SeparateChainingHashTable<>();
    while (in.hasNextLine()) {
        String[] connection = in.readLine().split(separator);
        int paper1 = Integer.parseInt(connection[0]);
        int paper2 = Integer.parseInt(connection[1]);
        if (paper1 == paper2 || paper1 > paper2) {
            // and maintain the digraph as a DAG
            continue;
        }
        if (!realDAGToFullDAGMap.contains(paper1)) {
            int paperVertex1Id = realDAGToFullDAGMap.size();
            realDAGToFullDAGMap.put(paper1, paperVertex1Id);
        }
        if (!realDAGToFullDAGMap.contains(paper2)) {
            int paperVertex2Id = realDAGToFullDAGMap.size();
            realDAGToFullDAGMap.put(paper2, paperVertex2Id);
        }
        int paperVertex1Id = realDAGToFullDAGMap.get(paper1);
        int paperVertex2Id = realDAGToFullDAGMap.get(paper2);
        fullDigraph.addEdge(paperVertex1Id, paperVertex2Id);
    }
    DirectedCycle directedCycle = new DirectedCycle(fullDigraph);
    if (directedCycle.hasCycle()) {
        throw new IllegalArgumentException("Digraph is not a DAG");
    }
    Digraph randomSubDigraph = new Digraph();
    SeparateChainingHashTable<Integer, Integer> digraphToSubDigraphMap = new SeparateChainingHashTable<>();
    List<DirectedEdge> allSubDigraphEdges = new ArrayList<>();
    for (int vertex = 0; vertex < randomVerticesToChoose; vertex++) {
        // Randomly choose a vertex between 1 and vertices
        int randomVertexId = StdRandom.uniform(fullDigraph.vertices) + 1;
        if (digraphToSubDigraphMap.contains(randomVertexId)) {
            continue;
        }
        int subDigraphVertexId = digraphToSubDigraphMap.size();
        digraphToSubDigraphMap.put(randomVertexId, subDigraphVertexId);
        randomSubDigraph.addVertex(subDigraphVertexId);
        for (int neighbor : fullDigraph.adjacent(randomVertexId)) {
            allSubDigraphEdges.add(new DirectedEdge(subDigraphVertexId, neighbor));
        }
    }
    // Randomly choose E directed edges from the subdigraph induced by the random vertices
    if (randomEdgesToChoose > allSubDigraphEdges.size()) {
        throw new IllegalArgumentException("Not enough edges to choose");
    }
    DirectedEdge[] allSubDigraphEdgesArray = new DirectedEdge[allSubDigraphEdges.size()];
    int allSubDigraphEdgesArrayIndex = 0;
    HashSet<Integer> edgesChosen = new HashSet<>();
    for (DirectedEdge directedEdge : allSubDigraphEdges) {
        allSubDigraphEdgesArray[allSubDigraphEdgesArrayIndex++] = directedEdge;
    }
    for (int edge = 0; edge < randomEdgesToChoose; edge++) {
        // Randomly choose an edge
        int randomEdgeId = StdRandom.uniform(allSubDigraphEdgesArray.length);
        if (edgesChosen.contains(randomEdgeId)) {
            continue;
        }
        edgesChosen.add(randomEdgeId);
        DirectedEdge randomEdge = allSubDigraphEdgesArray[randomEdgeId];
        if (!digraphToSubDigraphMap.contains(randomEdge.toVertex)) {
            int subDigraphNeighborVertexId = digraphToSubDigraphMap.size();
            digraphToSubDigraphMap.put(randomEdge.toVertex, subDigraphNeighborVertexId);
        }
        int subDigraphNeighborVertexId = digraphToSubDigraphMap.get(randomEdge.toVertex);
        randomSubDigraph.addEdge(randomEdge.fromVertex, subDigraphNeighborVertexId);
    }
    return randomSubDigraph;
}