The invention is a device for adapting a computer to enable identification of those subsets of a stream of signal values which form patterns when contraction mapped to an approximation of the attractor of a fractal. The machine currently employs an approximation of the attractor of an affine Sierpinski gasket. In principle, the fractal could be a Sierpinski carpet, Menger sponge, the Mandelbrot Set, or fractals constructed in polar or spherical coordinates. The stream of signal values and subsets of the stream can be displayed, segregated, or otherwise processed automatically by computer by reference to the mapped locations of the signal values. Selection sets can be employed manually to confine a visualized pattern as displayed on the map. Signal values which contribute to the confined pattern then are automatically identified. Some selection sets can be pre-set to automatically confine mapped signal values which fall within certain pre-determined patterns without visual inspection and manual confinement. The subsets of signal values identified by the selection sets are then available for further processing, including display of segregated subsets. The device enables display of segregated subsets of signal values in other display and analysis modes, such as the graphic phase space portraits of U.S. Pat. No. 5,218,530.