1. A computer-implemented system for generating document groupings, comprising: a lexicon of terms extracted from a set of documents and comprising a frequency of each extracted term within each document; concepts each comprising two or more of the extracted terms; a selection module to select a subset of the documents in the set based on the term frequencies; a grouping module to group the subset of documents into clusters based on the concepts; a similarity module to calculate a similarity of each document cluster with at least one document based on a distance by summing the frequency of each term in that document and a weight of the cluster for each of the terms; and an update module to update the weights until a rate of change for each cluster becomes constant.