Ejemplo n.º 1
0
// Entropic returns the entropic complexity of a segment of s defined by
// start and end.
func Entropic(s seq.Sequence, start, end int) (ce float64, err error) {
	if start < s.Start() || end > s.End() {
		err = fmt.Errorf("complex: index out of range")
		return
	}
	if start == end {
		return 0, nil
	}

	var N float64
	k := s.Alphabet().Len()
	logk := math.Log(float64(k))
	n := make([]float64, k)

	// tally classes
	it := s.Alphabet().LetterIndex()
	for i := start; i < end; i++ {
		if ind := it[s.At(i).L]; ind >= 0 {
			N++
			n[ind]++
		}
	}

	// -∑i=1..k((n_i/N)*log_k(n_i/N))
	for i := 0; i < k; i++ {
		if n[i] != 0 { // ignore zero counts
			ce += n[i] * logBaseK(logk, n[i]/N)
		}
	}
	ce = -ce / N

	return
}
Ejemplo n.º 2
0
// WF returns the Wootton and Federhen complexity of a segment of s defined by
// start and end.
func WF(s seq.Sequence, start, end int) (cwf float64, err error) {
	if start < s.Start() || end > s.End() {
		err = fmt.Errorf("complex: index out of range")
		return
	}
	if start == end {
		return 0, nil
	}

	var N int
	k := s.Alphabet().Len()
	logk := math.Log(float64(k))
	n := make([]int, k)

	// tally classes
	it := s.Alphabet().LetterIndex()
	for i := start; i < end; i++ {
		if ind := it[s.At(i).L]; ind >= 0 {
			N++
			n[ind]++
		}
	}

	// 1/N*log_k(N!/∏i=1..k(n_i!))
	cwf = lnFac(N)
	for i := 0; i < k; i++ {
		cwf -= lnFac(n[i])
	}
	cwf /= float64(N) * logk

	return
}
Ejemplo n.º 3
0
// Z returns the zlib compression estimate of complexity of a segment of s defined by
// start and end.
func Z(s seq.Sequence, start, end int) (cz float64, err error) {
	if start < s.Start() || end > s.End() {
		err = fmt.Errorf("complex: index out of range")
		return
	}
	if start == end {
		return 0, nil
	}

	bc := new(byteCounter)
	z := zlib.NewWriter(bc)
	defer z.Close()
	it := s.Alphabet().LetterIndex()
	var N float64
	for i := start; i < end; i++ {
		if b := byte(s.At(i).L); it[b] >= 0 {
			N++
			z.Write([]byte{b})
		}
	}
	z.Close()

	cz = (float64(*bc - overhead)) / N

	return
}