/** Computes the mean across all vectors in the input set of vectors */
static Vector average(List<Vector> ps) {
int numVectors = ps.size();
Vector out = new Vector(ps.get(0).elements());
// start from i = 1 since we already copied index 0 above
for (int i = 1; i < numVectors; i++) {
out.addInPlace(ps.get(i));
}
return out.divide(numVectors);
}
/** Computes the vector to which the input vector is closest using squared distance */
static int closestPoint(Vector p, List<Vector> centers) {
int bestIndex = 0;
double closest = Double.POSITIVE_INFINITY;
for (int i = 0; i < centers.size(); i++) {
double tempDist = p.squaredDist(centers.get(i));
if (tempDist < closest) {
closest = tempDist;
bestIndex = i;
}
}
return bestIndex;
}
