A system for generating user interface elements comprises a data analysis module, a receiver module and an element generation module. The data analysis module is arranged to identify a plurality of classes in input data, wherein each class is associated with a plurality of characteristic values each with a corresponding time stamp. The receiver module is arranged to receive a selection of a first time stamp, and the data analysis module is arranged to determine a first selection of the characteristic values each associated with the first time stamp. The element generation module is arranged to generate a plurality of user interface elements each associated with a class by calculating, for each user interface element, a two-dimensional area based on the characteristic value in the first selection associated with the class of the element.