Example usage for com.google.common.graph Network inDegree

Introduction

In this page you can find the example usage for com.google.common.graph Network inDegree.

Prototype

@Override
int inDegree(Object node);

Source Link

Document

Returns the number of #inEdges(Object) incoming edges in this graph of node .

Usage

From source file:org.apache.beam.runners.dataflow.worker.graph.Networks.java

/**
 * Returns a list of all distinct paths from roots of the network to leaves. The list can be in
 * arbitrary orders and can contain duplicate paths if there are multiple edges from two nodes.
 */// w  w  w .j  a v a2s.c  o m
public static <NodeT, EdgeT> List<List<NodeT>> allPathsFromRootsToLeaves(Network<NodeT, EdgeT> network) {
    ArrayDeque<List<NodeT>> paths = new ArrayDeque<>();
    // Populate the list with all roots
    for (NodeT node : network.nodes()) {
        if (network.inDegree(node) == 0) {
            paths.add(ImmutableList.of(node));
        }
    }

    List<List<NodeT>> distinctPathsFromRootsToLeaves = new ArrayList<>();
    while (!paths.isEmpty()) {
        List<NodeT> path = paths.removeFirst();
        NodeT lastNode = path.get(path.size() - 1);
        if (network.outDegree(lastNode) == 0) {
            distinctPathsFromRootsToLeaves.add(new ArrayList<>(path));
        } else {
            for (EdgeT edge : network.outEdges(lastNode)) {
                paths.addFirst(ImmutableList.<NodeT>builder().addAll(path)
                        .add(network.incidentNodes(edge).target()).build());
            }
        }
    }
    return distinctPathsFromRootsToLeaves;
}

---

From source file:org.apache.beam.runners.dataflow.worker.graph.Networks.java

/** Returns a set of nodes sorted in topological order. */
public static <N, E> Set<N> topologicalOrder(Network<N, E> network) {
    // TODO: Upgrade Guava and remove this method if topological sorting becomes
    // supported externally or remove this comment if its not going to be supported externally.

    checkArgument(network.isDirected(), "Only directed networks are supported, given %s", network);
    checkArgument(!network.allowsSelfLoops(), "Only networks without self loops are supported, given %s",
            network);//from w  w  w . j a v  a 2 s . co  m

    // Linked hashset will prevent duplicates from appearing and will maintain insertion order.
    LinkedHashSet<N> nodes = new LinkedHashSet<>(network.nodes().size());
    Queue<N> processingOrder = new ArrayDeque<>();
    // Add all the roots
    for (N node : network.nodes()) {
        if (network.inDegree(node) == 0) {
            processingOrder.add(node);
        }
    }

    while (!processingOrder.isEmpty()) {
        N current = processingOrder.remove();
        // If all predecessors have already been added, then we can add this node, otherwise
        // we need to add the node to the back of the processing queue.
        if (nodes.containsAll(network.predecessors(current))) {
            nodes.add(current);
            processingOrder.addAll(network.successors(current));
        } else {
            processingOrder.add(current);
        }
    }

    return nodes;
}

---