Java Code Examples for org.apache.giraph.graph.Vertex#getValue()

@Override
public void compute(final Vertex<ObjectWritable<Integer>, VertexValueWritable<IntWritable>, EdgeValueWritable<NullWritable>> vertex,
                    final Iterable<IntWritable> messages) throws IOException {
    VertexValueWritable<IntWritable> vertexValue = vertex.getValue();
    HBaseVertex v = vertexValue.getVertex();
    if (vertexValue.getValue() == null) {
        vertexValue.setValue(new IntWritable(((Number) v.id()).intValue()));
    }
    int value = vertexValue.getValue().get();
    boolean changed = false;
    for (IntWritable message : messages) {
        if (value < message.get()) {
            value = message.get();
            vertexValue.setValue(new IntWritable(value));
            changed = true;
        }
    }
    if (getSuperstep() == 0 || changed) {
        sendMessageToAllEdges(vertex, new IntWritable(value));
    }
    vertex.voteToHalt();
}
 

/**
 * Calculate this nodes contribution for the actual q value of the graph.
 */
private double calculateActualQ(Vertex<Text, LouvainNodeState, LongWritable> vertex, Iterable<LouvainMessage> messages) {
    // long start = System.currentTimeMillis();
    LouvainNodeState state = vertex.getValue();
    long k_i_in = state.getInternalWeight();
    for (LouvainMessage m : messages) {
        if (m.getCommunityId().equals(state.getCommunity())) {
            try {
                k_i_in += vertex.getEdgeValue(new Text(m.getSourceId())).get();
            } catch (NullPointerException e) {
                throw new IllegalStateException("Node: " + vertex.getId() + " does not have edge: " + m.getSourceId() + "  check that the graph is bi-directional.");
            }
        }
    }
    long sigma_tot = vertex.getValue().getCommunitySigmaTotal();
    long M = this.getTotalEdgeWeight();
    long k_i = vertex.getValue().getNodeWeight() + vertex.getValue().getInternalWeight();

    double q = ((((double) k_i_in) / M) - (((double) (sigma_tot * k_i)) / Math.pow(M, 2)));
    q = (q < 0) ? 0 : q;

    // long end = System.currentTimeMillis();
    // System.out.println("calculated actual q in :"+(end-start));
    return q;
}
 

@Override
public void compute(
        Vertex<ObjectWritable<Long>, VertexValueWritable<DoubleWritable>, EdgeValueWritable<FloatWritable>> vertex,
        Iterable<DoubleWritable> messages) throws IOException {
    VertexValueWritable<DoubleWritable> vertexValue = vertex.getValue();
    if (getSuperstep() == 0) {
        vertexValue.setValue(new DoubleWritable(Double.MAX_VALUE));
    }
    double minDist = isSource(vertex) ? 0d : Double.MAX_VALUE;
    for (DoubleWritable message : messages) {
        minDist = Math.min(minDist, message.get());
    }
    if (LOG.isDebugEnabled()) {
        LOG.debug("Vertex " + vertex.getId() + " got minDist = " + minDist +
                " vertex value = " + vertex.getValue());
    }
    if (minDist < vertexValue.getValue().get()) {
        vertexValue.setValue(new DoubleWritable(minDist));
        for (Edge<ObjectWritable<Long>, EdgeValueWritable<FloatWritable>> edge : vertex.getEdges()) {
            double distance = minDist + ((Number) edge.getValue().getEdge().property("weight").value()).doubleValue();
            if (LOG.isDebugEnabled()) {
                LOG.debug("Vertex " + vertex.getId() + " sent to " +
                        edge.getTargetVertexId() + " = " + distance);
            }
            sendMessage(edge.getTargetVertexId(), new DoubleWritable(distance));
        }
    }
    vertex.voteToHalt();
}
 

/**
 * Each vertex will recieve its own communities sigma_total (if updated),
 * and then send its currenty community info to each of its neighbors.
 *
 * @param messages
 */
private void getAndSendCommunityInfo(Vertex<Text, LouvainNodeState, LongWritable> vertex, Iterable<LouvainMessage> messages) {
    LouvainNodeState state = vertex.getValue();
    // set new community information.
    if (getSuperstep() > 0) {
        Iterator<LouvainMessage> it = messages.iterator();
        if (!it.hasNext()) {
            throw new IllegalStateException("No community info recieved in getAndSendCommunityInfo! Superstep: " + getSuperstep() + " id: " + vertex.getId());
        }
        LouvainMessage inMess = it.next();
        if (it.hasNext()) {
            throw new IllegalStateException("More than one community info packets recieved in getAndSendCommunityInfo! Superstep: " + getSuperstep() + " id: " + vertex.getId());
        }
        state.setCommunity(inMess.getCommunityId());
        state.setCommunitySigmaTotal(inMess.getCommunitySigmaTotal());
    }

    // send community info to all neighbors
    for (Edge<Text, LongWritable> edge : vertex.getEdges()) {
        LouvainMessage outMess = new LouvainMessage();
        outMess.setCommunityId(state.getCommunity());
        outMess.setCommunitySigmaTotal(state.getCommunitySigmaTotal());
        outMess.setEdgeWeight(edge.getValue().get());
        outMess.setSourceId(vertex.getId().toString());
        this.sendMessage(edge.getTargetVertexId(), outMess);
    }

}
 

/**
 * Based on community of each of its neighbors, each vertex determimnes if
 * it should retain its currenty community or swtich to a neighboring
 * communinity.
 * <p/>
 * At the end of this step a message is sent to the nodes community hub so a
 * new community sigma_total can be calculated.
 *
 * @param messages
 * @param iteration
 */
private void calculateBestCommunity(Vertex<Text, LouvainNodeState, LongWritable> vertex, Iterable<LouvainMessage> messages, int iteration) {

    LouvainNodeState state = vertex.getValue();

    // group messages by communities.
    HashMap<String, LouvainMessage> communityMap = new HashMap<String, LouvainMessage>();
    for (LouvainMessage message : messages) {

        String communityId = message.getCommunityId();
        long weight = message.getEdgeWeight();
        LouvainMessage newmess = new LouvainMessage(message);

        if (communityMap.containsKey(communityId)) {
            LouvainMessage m = communityMap.get(communityId);
            m.setEdgeWeight(m.getEdgeWeight() + weight);
        } else {
            communityMap.put(communityId, newmess);
        }
    }

    // calculate change in Q for each potential community
    String bestCommunityId = vertex.getValue().getCommunity();
    String startingCommunityId = bestCommunityId;
    BigDecimal maxDeltaQ = new BigDecimal("0.0");
    for (Map.Entry<String, LouvainMessage> entry : communityMap.entrySet()) {
        BigDecimal deltaQ = calculateQDelta(startingCommunityId, entry.getValue().getCommunityId(), entry.getValue().getCommunitySigmaTotal(), entry.getValue().getEdgeWeight(), state.getNodeWeight(), state.getInternalWeight());
        if (deltaQ.compareTo(maxDeltaQ) > 0 || (deltaQ.equals(maxDeltaQ) && entry.getValue().getCommunityId().compareTo(bestCommunityId) < 0)) {
            bestCommunityId = entry.getValue().getCommunityId();
            maxDeltaQ = deltaQ;
        }
    }

    // ignore switches based on iteration (prevent certain cycles)
    if ((state.getCommunity().compareTo(bestCommunityId) > 0 && iteration % 2 == 0) || (state.getCommunity().compareTo(bestCommunityId) < 0 && iteration % 2 != 0)) {
        bestCommunityId = state.getCommunity();
        // System.out.println("Iteration: "+iteration+" Node: "+getId()+" held stable to prevent cycle");
    }

    // update community and change count
    if (!state.getCommunity().equals(bestCommunityId)) {
        String old = state.getCommunity();
        LouvainMessage c = communityMap.get(bestCommunityId);
        if (!bestCommunityId.equals(c.getCommunityId())) {
            throw new IllegalStateException("Community mapping contains wrong Id");
        }
        state.setCommunity(c.getCommunityId());
        state.setCommunitySigmaTotal(c.getCommunitySigmaTotal());
        state.setChanged(1L);
        logger.debug("Iteration: {} Node: {} changed from {} -> {} dq: {}", iteration, vertex.getId(), old, state.getCommunity(), maxDeltaQ);
    }

    // send our node weight to the community hub to be summed in next
    // superstep
    this.sendMessage(new Text(state.getCommunity()), new LouvainMessage(state.getCommunity(), state.getNodeWeight() + state.getInternalWeight(), 0, vertex.getId().toString()));
}