Method nearest_centroid

nodedb-vector/src/quantize/pq.rs:245–256

(&self, subspace: usize, sub_vec: &[f32])

    }

    fn nearest_centroid(&self, subspace: usize, sub_vec: &[f32]) -> usize {
        let mut best_idx = 0;
        let mut best_dist = f32::MAX;
        for (i, centroid) in self.codebooks[subspace].iter().enumerate() {
            let d = l2_sub(sub_vec, centroid);
            if d < best_dist {
                best_dist = d;
                best_idx = i;
            }
        }
        best_idx
    }
}

/// L2 squared distance for sub-vectors (used in k-means and encoding).