1. A computer implemented method for clustering content according to similarity, the method comprising: receiving a set of features for a plurality of content items; calculating, by a processor, a distance matrix for the plurality of content items based on user navigation of at least some of the content items; labeling, by a processor, at least some of the content items as pairwise constraints based on the distance matrix; and creating, by a processor, a boosted cluster by incorporating the pairwise constraints into a clustering algorithm.