ans is widely used in computer vision, for example in the construction of vocabularies of visual features (visual words). In these applications the number \(n\) of points to cluster and/or the number \(K\) of clusters is often large. Unfortunately, minimizing the objective \(E\) is in general a difficult combinatorial problem, so locally optimal or approximated solutions are sought instead.</p>
<p>The basic K-means algorithm alternate between re-estimating the centers and the assignments (<a class="el" href