1. A method comprising: producing, by a system having a processor, visual structures to represent corresponding motifs, wherein the motifs correspond to repeating patterns in an input data set, wherein sizes of the visual structures are based on values of a characteristic associated with the motifs, and wherein a first of the motifs is nested within a second of the motifs to represent a hierarchical relationship of the patterns represented by the first and second motifs; dividing the input data set into plural parts; assigning weights to the corresponding plural parts according to densities of a particular type of motifs in the corresponding plural parts; using the assigned weights to distort the corresponding plural parts; presenting, by the system, the visual structures of corresponding motifs for display in a visualization screen, wherein the visualization screen depicts data in the input data set with the visual structures overlapping parts of depicted data; and receiving, by the system, interactive input specifying modification of a region containing motifs, wherein the specified modification includes interactive distortion of the visual structures in the region to change a size of the visual structures in the region.