public int speakerVote() {

         //Run through each element in the map to create a cumulative distribution

         Set<Integer> communityIds = communityDistribution.keySet();

         ArrayList<Integer> communities = new ArrayList<Integer>();

         ArrayList<Integer> cumulativeCounts = new ArrayList<Integer>();

         int sum=-1;

         for (Integer comm: communityIds) {

             sum += communityDistribution.get(comm);

             communities.add(comm);

             cumulativeCounts.add(sum);

         }

         //Generate a random integer in the range [0,sum)

         int rand = RandomNumGenerator.getRandomInt(sum+1);

         //Find the index of first value greater than rand in cumulativeCounts

         int i=0;

         for (i=0; i<cumulativeCounts.size(); i++) {

             if (cumulativeCounts.get(i)>=rand)

                 break;

         }

         //Return the corresponding community

         return communities.get(i);

     }

 public void updateLabels(Integer userId){

         Set<DefaultWeightedEdge> incomingEdges = userNodegraph.getGraph().incomingEdgesOf(userId);//获取所有该顶点的入度顶点

         Map<Integer, Integer> incomingVotes = new HashMap<Integer, Integer>();//所有speaker顶点投票情况

         //For each vertex V with an incoming edge to the current node

         for ( DefaultWeightedEdge edge: incomingEdges ) {

             int speakerId = userNodegraph.getGraph().getEdgeSource(edge);

             UserNode speakerNode = userNodegraph.getNodeMap().get(speakerId);

             int votedCommunity = speakerNode.speakerVote();

             int votedCommunitycount = 1;

             if ( incomingVotes.containsKey(votedCommunity)){

                 votedCommunitycount += incomingVotes.get(votedCommunity);

             }

             incomingVotes.put(votedCommunity, votedCommunitycount);

         }

         //Find the most popular vote

         Iterator<Entry<Integer, Integer>> it = incomingVotes.entrySet().iterator();

         int popularCommunity=-1;

         int popularCommunityCount=0;

         while ( it.hasNext()) {

             Entry<Integer, Integer> entry = it.next();

             if ( entry.getValue() > popularCommunityCount ) {

                 popularCommunity = entry.getKey();

                 popularCommunityCount = entry.getValue();

             }

         }

         //Update community distribution of the current node by 1

         UserNode currentNode = userNodegraph.getNodeMap().get(userId);

         currentNode.updateCommunityDistribution(popularCommunity, 1);

     }