A computer-implemented method executes instructions stored on a computer-readable medium. The method includes accessing a hierarchy of clusters, wherein each cluster includes at least one content file, and a label is associated with each cluster. The method further includes calculating a topic purity score for each cluster, and selecting a first cluster and a second cluster from the hierarchy of clusters, wherein the topic purity score of the first cluster and the second cluster are less than a purity threshold. The method also includes creating a third cluster by combining the content files included within the first cluster and the second cluster, determining a parent category of the first cluster and the second cluster, wherein the parent category is at a level within the hierarchy higher than a level of the first cluster and the second cluster, and associating a label of the parent category with the third cluster.