@Override
public void map(IntWritable nid, PersonalizedPageRankNode node, Context context)
throws IOException, InterruptedException {
for (int sourceIndex = 0; sourceIndex < sources.size(); sourceIndex++) {
float p = node.getPageRank(sourceIndex);
float jump = 0.0f;
float link = 0.0f;
// float jump = (float) (Math.log(ALPHA) - Math.log(nodeCnt));
// IS A SOURCE NODE
if (sources.get(sourceIndex) == node.getNodeId()) {
jump = (float) Math.log(ALPHA);
link =
(float) Math.log(1.0f - ALPHA)
+ sumLogProbs(p, (float) (Math.log(missingMass[sourceIndex])));
} else {
// NOT A SOURCE NODE
jump = (float) Math.log(0);
link = (float) Math.log(1.0f - ALPHA) + p;
}
p = sumLogProbs(jump, link);
node.setPageRank(sourceIndex, p);
}
context.write(nid, node);
}
@Override
public void map(IntWritable nid, PersonalizedPageRankNode node, Context context)
throws IOException, InterruptedException {
// Pass along node structure.
intermediateStructure.setNodeId(node.getNodeId());
intermediateStructure.setType(PersonalizedPageRankNode.Type.Structure);
intermediateStructure.setAdjacencyList(node.getAdjacenyList());
context.write(nid, intermediateStructure);
int massMessages = 0;
// Distribute PageRank mass to neighbors (along outgoing edges).
if (node.getAdjacenyList().size() > 0) {
// Each neighbor gets an equal share of PageRank mass.
ArrayListOfIntsWritable list = node.getAdjacenyList();
float mass[] = new float[sources.size()];
for (int i = 0; i < sources.size(); i++) {
mass[i] = node.getPageRank(i) - (float) StrictMath.log(list.size());
}
context.getCounter(PageRank.edges).increment(list.size());
// Iterate over neighbors.
for (int i = 0; i < list.size(); i++) {
neighbor.set(list.get(i));
intermediateMass.setNodeId(list.get(i));
intermediateMass.setType(PersonalizedPageRankNode.Type.Mass);
for (int j = 0; j < sources.size(); j++) {
intermediateMass.setPageRank(j, mass[j]);
}
// Emit messages with PageRank mass to neighbors.
context.write(neighbor, intermediateMass);
massMessages++;
}
}
// Bookkeeping.
context.getCounter(PageRank.nodes).increment(1);
context.getCounter(PageRank.massMessages).increment(massMessages);
}
