18. The system of claim 10 , further configured to receive the second plurality of documents, after the at least one label are assigned to each of the first plurality of previously clustered documents.
10. A system comprising: a non-transitory storage device configured to store a set of documents, the set of documents including a first plurality of previously clustered documents and a second plurality of documents, each of the first plurality of previously clustered documents having at least one label identifying a topic to which content of the document relates; a clustering engine configured to: partition documents from the set of documents into multiple clusters; and determine that a dominant topic exists within a first cluster of said multiple clusters; determine (i) a purity score representing a first ratio of a number of documents having a label identifying the dominant topic in the first cluster to a total number of previously clustered documents within the first cluster and (ii) a confidence measure representing a second ratio of the total number of previously clustered documents in the first cluster to a size of the first cluster, wherein the size of the first cluster equals a total number od documents included within the first cluster; and a labeling engine configured to assign a label identifying the dominant topic to at least documents from the second plurality of documents within said one of the multiple clusters when the purity score exceeds a first predetermined threshold and the confidence score exceeds a second predetermined threshold.