A fiirst version of LCS score function

pkg/obialign/lcs.go

@@ -0,0 +1,142 @@
+package obialign
+
+import (
+	"log"
+
+	"git.metabarcoding.org/lecasofts/go/obitools/pkg/obiseq"
+)
+
+func max(a, b int) int {
+	if a > b {
+		return a
+	}
+	return b
+}
+
+func min(a, b int) int {
+	if a < b {
+		return a
+	}
+	return b
+}
+
+type LCSMatrix struct {
+	matrix []int16 // Score matrix
+	lenght []int16 // Alignment length matrix
+	ll     int     // Length of the longest sequence
+	l      int     // Length of the shortest sequence
+	delta  int     // ll - l
+	extra  int
+	w      int
+}
+
+func NewLCSMatrix(matrix *LCSMatrix, L, l int, maxError int) *LCSMatrix {
+	if matrix == nil {
+		matrix = &LCSMatrix{}
+	}
+
+	if l > L {
+		log.Panicf("L (%d) must be greater or equal to l (%d)", L, l)
+	}
+
+	delta := L - l
+	extra := ((maxError - delta) / 2) + 1
+
+	needed := L * (1 + delta + 2*extra)
+
+	if needed > matrix.Cap() {
+		matrix.matrix = make([]int16, needed)
+		matrix.lenght = make([]int16, needed)
+	}
+
+	matrix.matrix = matrix.matrix[:needed]
+	matrix.lenght = matrix.lenght[:needed]
+
+	matrix.ll = L
+	matrix.l = l
+	matrix.delta = delta
+	matrix.extra = extra
+	matrix.w = delta + 1 + 2*extra
+
+	return matrix
+}
+
+func (matrix *LCSMatrix) Cap() int {
+	return cap(matrix.matrix)
+}
+
+func (matrix *LCSMatrix) Length() int {
+	return len(matrix.matrix)
+}
+
+func (matrix *LCSMatrix) Get(i, j int) (int16, int16) {
+	ij := max(0, i-matrix.extra)
+	sj := min(i+matrix.delta+matrix.extra, matrix.ll)
+
+	switch {
+	case i == 0:
+		return int16(0), int16(j)
+	case j == 0:
+		return int16(0), int16(i)
+	case j < ij || j > sj:
+		return -1, 30000
+	default:
+		return matrix.matrix[matrix.extra+matrix.w*(i-1)+(matrix.w-1)*(j-i)],
+			matrix.lenght[matrix.extra+matrix.w*(i-1)+(matrix.w-1)*(j-i)]
+	}
+}
+
+func (matrix *LCSMatrix) Set(i, j int, score, length int16) {
+	ij := max(0, i-matrix.extra)
+	sj := min(i+matrix.delta+matrix.extra, matrix.ll)
+
+	if i > 0 && j > 0 && j >= ij && j <= sj {
+		matrix.matrix[matrix.extra+matrix.w*(i-1)+(matrix.w-1)*(j-i)] = score
+		matrix.lenght[matrix.extra+matrix.w*(i-1)+(matrix.w-1)*(j-i)] = length
+	}
+}
+
+func LCSScore(seqA, seqB *obiseq.BioSequence, maxError int,
+	matrix *LCSMatrix) (int, int) {
+	// swapped := false
+
+	if seqA.Length() < seqB.Length() {
+		seqA, seqB = seqB, seqA
+		// swapped = true
+	}
+
+	if (seqA.Length() - seqB.Length()) > maxError {
+		return -1, -1
+	}
+
+	matrix = NewLCSMatrix(matrix, seqA.Length(), seqB.Length(), maxError)
+
+	for i := 1; i <= matrix.l; i++ {
+		ij := max(1, i-matrix.extra)
+		sj := min(i+matrix.delta+matrix.extra, matrix.ll)
+		for j := ij; j <= sj; j++ {
+			sd, ld := matrix.Get(i-1, j-1)
+			if seqB.Sequence()[i-1] == seqA.Sequence()[j-1] {
+				sd++
+			}
+			sup, lup := matrix.Get(i-1, j)
+			sleft, lleft := matrix.Get(i, j-1)
+			switch {
+			case sd >= sup && sd >= sleft:
+				matrix.Set(i, j, sd, ld+1)
+			case sup >= sleft && sup >= sd:
+				matrix.Set(i, j, sup, lup+1)
+			default:
+				matrix.Set(i, j, sleft, lleft+1)
+			}
+		}
+	}
+
+	s, l := matrix.Get(seqB.Length(), seqA.Length())
+
+	if (l - s) > int16(maxError) {
+		return -1, -1
+	}
+
+	return int(s), int(l)
+}