18. A non-transitory computer readable medium containing instructions which, when executed by one or more processing devices, perform a method of generating a query for identifying documents subject to a litigation hold, the method comprising: receiving a training set of documents, wherein each document in the set of training documents is given a relevance indicator; receiving an initial query including one or more initial keywords; querying the training set of documents based on the initial query; determining a spatial proximity between one of the initial keywords and a set of keywords in the training set of documents; generating, by one or more processing devices, a set of one or more neighboring queries based on the spatial proximity, the neighboring queries including one or more additional keywords; evaluating each of the one or more neighboring queries in the set by assigning a quality score, including determining a highest ranked neighboring query; repeating the generating a set of one or more neighboring queries and evaluating each of the one or more neighboring queries, wherein the highest ranked neighboring query is provided as the initial query, until it is determined that a quality score of the highest ranked neighboring query is less than a quality score of the initial query, wherein a previously highest ranked neighboring query with a quality score greater than or equal to the quality of the initial query is a resultant query; and presenting the resultant query to a user.
18. A non-transitory computer readable medium containing instructions which, when executed by one or more processing devices, perform a method of generating a query for identifying documents subject to a litigation hold, the method comprising: receiving a training set of documents, wherein each document in the set of training documents is given a relevance indicator; receiving an initial query including one or more initial keywords; querying the training set of documents based on the initial query; determining a spatial proximity between one of the initial keywords and a set of keywords in the training set of documents; generating, by one or more processing devices, a set of one or more neighboring queries based on the spatial proximity, the neighboring queries including one or more additional keywords; evaluating each of the one or more neighboring queries in the set by assigning a quality score, including determining a highest ranked neighboring query; repeating the generating a set of one or more neighboring queries and evaluating each of the one or more neighboring queries, wherein the highest ranked neighboring query is provided as the initial query, until it is determined that a quality score of the highest ranked neighboring query is less than a quality score of the initial query, wherein a previously highest ranked neighboring query with a quality score greater than or equal to the quality of the initial query is a resultant query; and presenting the resultant query to a user. 19. The computer readable medium of claim 18 , wherein the neighboring queries are evaluated based on one or more of the precision of the query, recall of the query, or the F 1 score of the query.