@Override
public void init(String prefix) {
// initialize global arm model
GlobalArmModel.initialize(prefix);
// initialize static fields
K = (double) GlobalArmModel.numberOfArms();
d = GlobalArmModel.getDValue();
// initialize counters
n = new double[GlobalArmModel.numberOfArms()];
Arrays.fill(n, 0.0);
sumN = 0.0;
// model
s = Arrays.copyOf(n, n.length);
w = Arrays.copyOf(n, n.length);
r = Arrays.copyOf(n, n.length);
q = Arrays.copyOf(n, n.length);
f = Arrays.copyOf(n, n.length);
g = Arrays.copyOf(n, n.length);
// parameter
c = Configuration.getDouble(prefix + ".p2greedy.C");
}
public int update() {
final double N = (double) Network.size();
// final double m = Math.log(N)/Math.log(2.0);
final double t = (double) ++age;
// final double eps = c*K/(d*d*t*N*N);
final double eps = Math.min(1.0, c * K / (d * d * t * N));
int I = 0; // index of the arm which will be played in the current run
if (t == 1) {
I = CommonState.r.nextInt(GlobalArmModel.numberOfArms());
} else {
final double r = CommonState.r.nextDouble();
if (r < eps) {
// random
I = CommonState.r.nextInt(GlobalArmModel.numberOfArms());
} else {
// best
I = bestArmIdx();
}
}
// play arm I
final double xi = GlobalArmModel.playMachine(I);
// update
if (Utils.isPower2(t)) {
addAndSetTo0(s, r);
addAndSetTo0(w, q);
addAndSetTo0(r, f);
addAndSetTo0(q, g);
}
final double mul = N / 2.0;
f[I] += mul * xi;
g[I] += mul;
// update counters
n[I]++;
sumN++;
return I;
}
