Skews from custom sequences

To compute skews, the input sequence is scanned with a sliding window, and the requested parameter is calculate for each window. The data is shown in a graph.

G+C %
The porcentaje of G+C is computed

GC-skew
For each window, (G-C)/(G+C) is computed, where G and C are the number of ocurrences for each nucleotide

AT-skew
For each window, (A-T)/(A+T) is computed, where A and T are the number of ocurrences for each nucleotide.

KETO-skew
For each window, (G+C-A-T)/(G+C+A+T) is computed, where A, C, G and T are the number of ocurrences for each nucleotide.

Oligo-skew
For each window, frecuencies for all nucleotides with selected length is computed. Those frecuencies are compared to frecuencies obtained from the complete sequence. When comparing both frecuencies, global distance is computed, as described by Almeida et al. (2001)