1. A method comprising: receiving, by machine logic of a computer, a set of vector data, wherein the set of vector data includes a plurality of vector values from each class of a plurality of classes; applying, by machine logic of the computer, an inter-class filtering to the set of vector data, wherein the inter-class filtering is based, at least in part, on an inter-class distance; and applying, by machine logic of the computer, an intra-class filtering to the set of vector data, wherein the intra-class filtering is based, at least in part, on an intra-class distance; wherein: the inter-class distance is based on a sum of distances between: (i) a subject vector value in the plurality of vector values; and (ii) at least some of the vector values in the plurality of vector values of at least one other class of the plurality of classes; and the intra-class distance is based on a sum of distances between: (i) a subject vector value in the plurality of vector values in a first class of the plurality of classes; and (ii) at least some of the vector values in the plurality of vector values of the first class.