1. A computer-implemented method for processing a data set composed of a plurality of data vectors that each includes a plurality of data values respectively associated with a plurality of variables in a variable space, comprising: Populating a first data structure with a plurality of entries that correspond to respective ones of said data vectors; and iteratively repeating operations of: performing correlation calculations to determine for every pair of entries in said first data structure a correlation value indicative of a correlation between the associated pair of data vectors, using the correlation values to identify one said pair of entries that has an associated pair of data vectors are closer to one another in the variable space than any other pair of data vectors associated with any other pair of entries, recording the identified pair of entries in a second data structure, merging the pair of data vectors associated with the identified pair of entries to define a merged data vector, and replacing the identified pair of entries in the first data structure with an entry corresponding to the merged data vector.