1. A method for grouping of data in a set of data points based on similarity or connectivity of what the data represent, comprising: selecting an initial set of data points; defining a measure of similarity or connection, and constructing a similarity or connectivity matrix showing which data points are similar or connected according to the measure; computing eigenvectors of the similarity or connectivity matrix, using a computer; and associating lineal sub-spaces in an eigenvector space with groupings of the data points in the initial set of data points.