Algorithm for CGR and k -mer table. (a) CGR is generated by iterating the movement of pointer to the midpoint of current position and the vertex corresponding to the next nucleotide within a given sequence in reverse order. Here the reverse order is used to match the coordinate system of CGR and k-mer table. (b) k-mer table is generated by repeated division of the square into four quadrants representing the four nucleotides. Note that ACGT position is identical in CGR and k-mer table.