11. A method for grouping cluster spines into a two-dimensional visual display space, comprising: obtaining clusters of concepts each extracted from one or more documents and forming spines by placing the clusters sharing at least one of the concepts along a vector; ordering the spines based on a length of each spine; selecting one or more of the spines, each unique from the other spines, as unique spines and placing the unique spines into a visual display space; determining a similarity between at least one of the spines not placed and each of the placed unique spines and identifying the placed unique spine most similar; selecting at least one anchor cluster on the most similar unique spine that satisfies a threshold similarity with the unplaced spine; identifying one of the clusters on the unplaced spine that is most similar to the selected anchor cluster and grafting the most similar cluster to the selected anchor cluster such that the unplaced spine is positioned along a vector extending from a center of the selected anchor cluster to form a group of cluster spines; and displaying the group of cluster spines in the visual display space.
11. A method for grouping cluster spines into a two-dimensional visual display space, comprising: obtaining clusters of concepts each extracted from one or more documents and forming spines by placing the clusters sharing at least one of the concepts along a vector; ordering the spines based on a length of each spine; selecting one or more of the spines, each unique from the other spines, as unique spines and placing the unique spines into a visual display space; determining a similarity between at least one of the spines not placed and each of the placed unique spines and identifying the placed unique spine most similar; selecting at least one anchor cluster on the most similar unique spine that satisfies a threshold similarity with the unplaced spine; identifying one of the clusters on the unplaced spine that is most similar to the selected anchor cluster and grafting the most similar cluster to the selected anchor cluster such that the unplaced spine is positioned along a vector extending from a center of the selected anchor cluster to form a group of cluster spines; and displaying the group of cluster spines in the visual display space. 14. A method according to claim 11 , wherein the most similar anchor cluster comprises a weak anchor cluster comprising a minimum similarity with the unplaced spine.