It is specifically the folder partition tree on the rows that allows one to define a corresponding generalized earth mover metric between columns; this means that the expected value of a column on a row folder (bin) is a new "meta" coordinate, and the scaled distance between two columns in scaled "meta coordinates" leads to a generalized earth mover's distance (gEMD) between the columns. This metric can now be used to build a new partition tree on the columns which, in turn, is used to build a new partition tree on the rows. The procedure eventually converges to a fixed pair of partition tree metrics.