work on obiclean chimera detection

pkg/obiseq/iupac_nog.go

@@ -0,0 +1,28 @@
+package obiseq
+
+var _iupac = [26]byte{
+	//  a   b  c  d   e  f
+	1, 14, 2, 13, 0, 0,
+	//  g   h  i  j  k   l
+	4, 11, 0, 0, 12, 0,
+	//  m   n  o  p  q  r
+	3, 15, 0, 0, 0, 5,
+	//  s  t  u   v  w  x
+	6, 8, 8, 13, 9, 0,
+	//  y   z
+	10, 0,
+}
+
+func SameIUPACNuc(a, b byte) bool {
+	if (a >= 'A') && (a <= 'Z') {
+		a |= 32
+	}
+	if (b >= 'A') && (b <= 'Z') {
+		b |= 32
+	}
+
+	if (a >= 'a') && (a <= 'z') && (b >= 'a') && (b <= 'z') {
+		return (_iupac[a-'a'] & _iupac[b-'a']) > 0
+	}
+	return a == b
+}