A clustering system includes a visual mapping sub-system configured to display an N-dimensional to two- or three-dimensional mapping of items to be clustered, where N is greater than three, the mapping having mapping parameters for the N-dimensions. A user interface sub-system is configured to receive user inputted values for the mapping parameters, user inputted values selecting whether selected mapping parameters are fixed or adjustable, and user inputted values associating selected items with selected groups. An adjustment sub-system is configured to adjust the adjustable mapping parameters, without adjusting any fixed mapping parameters, to improve a measure of distinctness of one or more groups of items in the two- or three-dimensional mapping.