17. A system according to claim 11 , further comprising: a reference set module to generate the reference concepts from a set of concepts, comprising at least one of: a comparison module to identify the concepts that are dissimilar from each other concept in the concept set and to assign the classification code to each of the dissimilar concepts, as the reference concepts; and a reference clustering module to group the set of concepts into one or more clusters, to select one or more of the concepts in at least one cluster, and to assign the classification code to each of the selected concepts, as the reference concepts.
11. A system for displaying relationships between concepts to provide classification suggestions via nearest neighbor, comprising: a database to maintain reference concepts each associated with a classification code and a set of uncoded concepts, wherein each of the reference concepts and the uncoded concepts comprises one or more nouns extracted from a plurality of documents; an association module to associate each reference concept with a symbol representing the classification code; a similarity module to compare at least one uncoded concept with the reference concepts and to identify one or more of the reference concepts that are similar to the at least one uncoded concept; a display to display relationships between the at least one uncoded concept and the similar reference concepts for classifying the at least one uncoded concept based on the classification symbols of the similar reference concepts comprising at least one of: a presence module to display one or more of a presence and absence of the similar reference concepts with different classification codes; and a quantity module to display a quantity of the similar reference concepts for each of the different classification codes; a suggestion module to provide at least one visual classification suggestion based on the displayed relationships; a classification module to receive a classification code for the at least one uncoded concept from a human reviewer based on the at least one suggestion; and a computer processor to execute the modules.