// global svd P Q
private void buildGlobalModel() throws Exception {
for (int iter = 1; iter <= numIters; iter++) {
for (MatrixEntry me : trainMatrix) {
int u = me.row(); // user
int i = me.column(); // item
double rui = me.get();
double pui = DenseMatrix.rowMult(P, u, Q, i);
double eui = rui - pui;
// update factors
for (int f = 0; f < numFactors; f++) {
double puf = P.get(u, f), qif = Q.get(i, f);
P.add(u, f, lRate * (eui * qif - regU * puf));
Q.add(i, f, lRate * (eui * puf - regI * qif));
}
}
} // end of training
}
@Override
protected double predict(int u, int j) {
return globalMean + DenseMatrix.rowMult(P, u, Q, j);
}
