A visual analytics system includes a memory and a processor. The processor executes a clustering application having an interactive user-interface rendered on a client computer. The clustering application determines a first cluster of data items of a data set, the data items in the first cluster having first attribute values that are similar to each other within a first degree of similarity and determines a second cluster of data items of the data set, the data items in the second cluster having second attribute values that are similar to each other within a second degree of similarity. For visual analytics, the user interface receives a user selection of a third degree of similarity. In response to which, the clustering application determines a third cluster of data items of the data set, the data items in the third cluster being dissimilar to either the first attribute value of the first reference data item or the second attribute value of the second reference data item by at least the third degree of similarity, and visually displays the third cluster of data items on the user interface.