public static Counter PersonalizedPageRank(Counter seedVector, SparseMatrix transitionMat) {
double trimEps = 0.0;
int iterLimit = 200;
transitionMat = transitionMat.stochasticizeRows();
double beta = 0.85;
long start;
long end;
Counter vector = new Counter(seedVector);
double svCard = 0;
for (int i : seedVector.keySet()) {
svCard += seedVector.get(i);
}
Counter oldVector = new Counter(vector);
vector = transitionMat.multiply(vector);
double diff = 1;
int t = 0;
start = System.currentTimeMillis();
while (diff > Math.pow(10.0, -10.0) && (diff < 3.99999 || diff > 4.00001) && t < iterLimit) {
t += 1;
vector.trimKeys(trimEps);
vector = transitionMat.multiply(vector);
Set<Integer> vecSeedUnion = vector.concreteKeySet();
vecSeedUnion.addAll(seedVector.concreteKeySet());
for (int i : vecSeedUnion) {
// vector.set(i,
// beta*vector.get(i)/norm+(1-beta)*seedVector.get(i));///Math.max(norm,1.0));
vector.set(
i,
beta * vector.get(i)
+ (1 - beta) * seedVector.get(i) / svCard); // /Math.max(norm,1.0));
}
double norm = 0;
for (int i : vector.keySet()) {
// norm += vector.get(i)*vector.get(i);
// norm += Math.abs(vector.get(i));
norm += vector.get(i);
}
// norm = Math.sqrt(norm);
diff = 0;
Set<Integer> vecOldUnion = vector.concreteKeySet();
vecOldUnion.addAll(oldVector.concreteKeySet());
for (int i : vecOldUnion) {
diff += (oldVector.get(i) - vector.get(i)) * (oldVector.get(i) - vector.get(i));
}
System.out.println(diff + " " + norm);
// System.out.println(vector.toString());
// System.out.println(oldVector.toString());
oldVector = new Counter(vector);
}
// System.out.println(transitionMat.toStringValues());
end = System.currentTimeMillis();
System.out.println("Time: " + (end - start) + " iterations: " + t);
return vector;
}
public Counter multiply(Counter vector) {
Counter resVec = new Counter();
// for(int r: vector.keySet()){
// Counter row = this.getRow(r);
// double sum = 0;
// for(int c: row.keySet()){
//// resVec.add(r, row.get(c)*vector.get(c));
// sum += row.get(c)*vector.get(c);
// }
// resVec.add(r, sum);
// }
for (int r : rows) {
resVec.set(r, this.getRow(r).dot(vector));
}
return resVec;
}
/** Test method for {@link org.apache.niolex.commons.test.Counter#cnt()}. */
@Test
public void testCnt() {
Counter c = new Counter();
c.set(1123);
assertEquals(1123, c.cnt());
}