diff --git a/pkg/obiiter/workers.go b/pkg/obiiter/workers.go
index 51331c3..bf5bb5e 100644
--- a/pkg/obiiter/workers.go
+++ b/pkg/obiiter/workers.go
@@ -19,6 +19,14 @@ func AnnotatorToSeqWorker(function SeqAnnotator) SeqWorker {
 	return f
 }
 
+// That method allows for applying a SeqWorker function on every sequences.
+//
+// Sequences are provided by the iterator and modified sequences are pushed
+// on the returned IBioSequenceBatch.
+//
+// Moreover the SeqWorker function, the method accepted two optional integer parameters.
+//   - First is allowing to indicates the number of workers running in parallele (default 4)
+//   - The second the size of the chanel buffer. By default set to the same value than the input buffer.
 func (iterator IBioSequenceBatch) MakeIWorker(worker SeqWorker, sizes ...int) IBioSequenceBatch {
 	nworkers := 4
 	buffsize := iterator.BufferSize()
@@ -61,6 +69,51 @@ func (iterator IBioSequenceBatch) MakeIWorker(worker SeqWorker, sizes ...int) IB
 	return newIter
 }
 
+func (iterator IBioSequenceBatch) MakeIConditionalWorker(predicate obiseq.SequencePredicate,
+	worker SeqWorker, sizes ...int) IBioSequenceBatch {
+	nworkers := 4
+	buffsize := iterator.BufferSize()
+
+	if len(sizes) > 0 {
+		nworkers = sizes[0]
+	}
+
+	if len(sizes) > 1 {
+		buffsize = sizes[1]
+	}
+
+	newIter := MakeIBioSequenceBatch(buffsize)
+
+	newIter.Add(nworkers)
+
+	go func() {
+		newIter.WaitAndClose()
+		log.Debugln("End of the batch workers")
+
+	}()
+
+	f := func(iterator IBioSequenceBatch) {
+		for iterator.Next() {
+			batch := iterator.Get()
+			for i, seq := range batch.slice {
+				if predicate(batch.slice[i]) {
+					batch.slice[i] = worker(seq)
+				}
+			}
+			newIter.Push(batch)
+		}
+		newIter.Done()
+	}
+
+	log.Debugln("Start of the batch workers")
+	for i := 0; i < nworkers-1; i++ {
+		go f(iterator.Split())
+	}
+	go f(iterator)
+
+	return newIter
+}
+
 func (iterator IBioSequenceBatch) MakeISliceWorker(worker SeqSliceWorker, sizes ...int) IBioSequenceBatch {
 	nworkers := 4
 	buffsize := iterator.BufferSize()
diff --git a/pkg/obiseq/biosequence.go b/pkg/obiseq/biosequence.go
index 64e67e8..d5bafc3 100644
--- a/pkg/obiseq/biosequence.go
+++ b/pkg/obiseq/biosequence.go
@@ -199,7 +199,7 @@ func (s *BioSequence) Annotations() Annotation {
 }
 
 // A method that returns the value of the key in the annotation map.
-func (s *BioSequence) Get(key string) (interface{}, bool) {
+func (s *BioSequence) GetAttribute(key string) (interface{}, bool) {
 	var val interface{}
 	ok := s.annotations != nil
 
@@ -210,12 +210,17 @@ func (s *BioSequence) Get(key string) (interface{}, bool) {
 	return val, ok
 }
 
+func (s *BioSequence) SetAttribute(key string, value interface{}) {
+	annot := s.Annotations()
+	annot[key] = value
+}
+
 // A method that returns the value of the key in the annotation map.
-func (s *BioSequence) GetInt(key string) (int, bool) {
+func (s *BioSequence) GetIntAttribute(key string) (int, bool) {
 	var val int
 	var err error
 
-	v, ok := s.Get(key)
+	v, ok := s.GetAttribute(key)
 
 	if ok {
 		val, err = goutils.InterfaceToInt(v)
@@ -226,9 +231,9 @@ func (s *BioSequence) GetInt(key string) (int, bool) {
 }
 
 // A method that returns the value of the key in the annotation map.
-func (s *BioSequence) GetString(key string) (string, bool) {
+func (s *BioSequence) GetStringAttribute(key string) (string, bool) {
 	var val string
-	v, ok := s.Get(key)
+	v, ok := s.GetAttribute(key)
 
 	if ok {
 		val = fmt.Sprint(v)
@@ -242,7 +247,7 @@ func (s *BioSequence) GetBool(key string) (bool, bool) {
 	var val bool
 	var err error
 
-	v, ok := s.Get(key)
+	v, ok := s.GetAttribute(key)
 
 	if ok {
 		val, err = goutils.InterfaceToBool(v)
@@ -259,7 +264,7 @@ func (s *BioSequence) MD5() [16]byte {
 
 // Returning the number of times the sequence has been observed.
 func (s *BioSequence) Count() int {
-	count, ok := s.GetInt("count")
+	count, ok := s.GetIntAttribute("count")
 
 	if !ok {
 		count = 1
@@ -270,7 +275,7 @@ func (s *BioSequence) Count() int {
 
 // Returning the taxid of the sequence.
 func (s *BioSequence) Taxid() int {
-	taxid, ok := s.GetInt("taxid")
+	taxid, ok := s.GetIntAttribute("taxid")
 
 	if !ok {
 		taxid = 1
@@ -330,6 +335,12 @@ func (s *BioSequence) WriteByteQualities(data byte) error {
 	return nil
 }
 
+// Clearing the sequence.
+func (s *BioSequence) ClearQualities() {
+	s.qualities = s.qualities[0:0]
+}
+
+
 // A method that appends a byte slice to the sequence.
 func (s *BioSequence) Write(data []byte) (int, error) {
 	s.sequence = append(s.sequence, data...)
@@ -347,3 +358,8 @@ func (s *BioSequence) WriteByte(data byte) error {
 	s.sequence = append(s.sequence, data)
 	return nil
 }
+
+// Clearing the sequence.
+func (s *BioSequence) Clear() {
+	s.sequence = s.sequence[0:0]
+}
diff --git a/pkg/obitax/path.go b/pkg/obitax/path.go
index e44daee..19bec5e 100644
--- a/pkg/obitax/path.go
+++ b/pkg/obitax/path.go
@@ -2,6 +2,8 @@ package obitax
 
 import (
 	"fmt"
+
+	log "github.com/sirupsen/logrus"
 )
 
 func (taxon *TaxNode) Path() (*TaxonSlice, error) {
@@ -22,6 +24,34 @@ func (taxon *TaxNode) Path() (*TaxonSlice, error) {
 	return &path, nil
 }
 
+func (taxon *TaxNode) TaxonAtRank(rank string) *TaxNode {
+	for taxon.rank != rank && taxon != taxon.pparent {
+		taxon = taxon.pparent
+
+		if taxon == nil {
+			log.Panicln("Taxonomy must be reindexed")
+		}
+	}
+
+	if taxon == taxon.pparent {
+		taxon = nil
+	}
+
+	return taxon
+}
+
+func (taxon *TaxNode) Species() *TaxNode {
+	return taxon.TaxonAtRank("species")
+}
+
+func (taxon *TaxNode) Genus() *TaxNode {
+	return taxon.TaxonAtRank("genus")
+}
+
+func (taxon *TaxNode) Family() *TaxNode {
+	return taxon.TaxonAtRank("family")
+}
+
 // Returns a TaxonSet listing the requested taxon and all
 // its ancestors in the taxonomy down to the root.
 func (taxonomy *Taxonomy) Path(taxid int) (*TaxonSlice, error) {
diff --git a/pkg/obitax/sequence_methods.go b/pkg/obitax/sequence_methods.go
new file mode 100644
index 0000000..08b8ee0
--- /dev/null
+++ b/pkg/obitax/sequence_methods.go
@@ -0,0 +1,37 @@
+package obitax
+
+import (
+	"git.metabarcoding.org/lecasofts/go/obitools/pkg/obiseq"
+)
+
+// Setting the taxon at a given rank for a given sequence.
+//
+// Two attributes are added to the sequence. One named by the rank name stores
+// the taxid, a second named by the rank name suffixed with '_name' contains the
+// Scientific name of the genus.
+// If the taxon at the given rank doesn't exist for the taxonomy annotation
+// of the sequence, nothing happens.
+func (taxonomy *Taxonomy) SetTaxonAtRank(sequence *obiseq.BioSequence, rank string) *TaxNode {
+	taxid := sequence.Taxid()
+	taxon, err := taxonomy.Taxon(taxid)
+	taxonAtRank := taxon.TaxonAtRank(rank)
+
+	if err == nil && taxonAtRank != nil {
+		sequence.SetAttribute(rank, taxonAtRank.taxid)
+		sequence.SetAttribute(rank+"_name", taxonAtRank.scientificname)
+	}
+
+	return taxonAtRank
+}
+
+func (taxonomy *Taxonomy) SetSpecies(sequence *obiseq.BioSequence) *TaxNode {
+	return taxonomy.SetTaxonAtRank(sequence, "species")
+}
+
+func (taxonomy *Taxonomy) SetGenus(sequence *obiseq.BioSequence) *TaxNode {
+	return taxonomy.SetTaxonAtRank(sequence, "genus")
+}
+
+func (taxonomy *Taxonomy) SetFamily(sequence *obiseq.BioSequence) *TaxNode {
+	return taxonomy.SetTaxonAtRank(sequence, "family")
+}
diff --git a/pkg/obitax/sequence_predicate.go b/pkg/obitax/sequence_predicate.go
index 9379e49..3ca6d94 100644
--- a/pkg/obitax/sequence_predicate.go
+++ b/pkg/obitax/sequence_predicate.go
@@ -22,7 +22,10 @@ func (taxonomy *Taxonomy) IsAValidTaxon(withAutoCorrection ...bool) obiseq.Seque
 		if err == nil && taxon.taxid != taxid {
 			if autocorrection {
 				sequence.SetTaxid(taxon.taxid)
-				log.Printf("Sequence %s : Taxid %d updated with %d", taxid, taxon.taxid)
+				log.Printf("Sequence %s : Taxid %d updated with %d",
+					sequence.Id(),
+					taxid,
+					taxon.taxid)
 			} else {
 				if _, ok := deprecatedTaxidsWarning[taxid]; !ok {
 					deprecatedTaxidsWarning[taxid] = true
diff --git a/pkg/obitax/sequence_workers.go b/pkg/obitax/sequence_workers.go
new file mode 100644
index 0000000..bfa591b
--- /dev/null
+++ b/pkg/obitax/sequence_workers.go
@@ -0,0 +1,56 @@
+package obitax
+
+import (
+	"git.metabarcoding.org/lecasofts/go/obitools/pkg/goutils"
+	"git.metabarcoding.org/lecasofts/go/obitools/pkg/obiiter"
+	"git.metabarcoding.org/lecasofts/go/obitools/pkg/obiseq"
+	log "github.com/sirupsen/logrus"
+)
+
+func (taxonomy *Taxonomy) MakeSetTaxonAtRankWorker(rank string) obiiter.SeqWorker {
+
+	if !goutils.Contains(taxonomy.RankList(), rank) {
+		log.Fatalf("%s is not a valid rank (allowed ranks are %v)",
+			rank,
+			taxonomy.RankList())
+	}
+
+	w := func(sequence *obiseq.BioSequence) *obiseq.BioSequence {
+		taxonomy.SetTaxonAtRank(sequence, rank)
+		return sequence
+	}
+
+	return w
+}
+
+func (taxonomy *Taxonomy) MakeSetSpeciesWorker() obiiter.SeqWorker {
+
+	w := func(sequence *obiseq.BioSequence) *obiseq.BioSequence {
+		taxonomy.SetSpecies(sequence)
+		return sequence
+	}
+
+	return w
+}
+
+func (taxonomy *Taxonomy) MakeSetGenusWorker() obiiter.SeqWorker {
+
+	w := func(sequence *obiseq.BioSequence) *obiseq.BioSequence {
+		taxonomy.SetGenus(sequence)
+		return sequence
+	}
+
+	return w
+}
+
+func (taxonomy *Taxonomy) MakeSetFamilyWorker() obiiter.SeqWorker {
+
+	w := func(sequence *obiseq.BioSequence) *obiseq.BioSequence {
+		taxonomy.SetFamily(sequence)
+		return sequence
+	}
+
+	return w
+}
+
+
diff --git a/pkg/obitools/obiclean/graph.go b/pkg/obitools/obiclean/graph.go
index cce3218..6d67d60 100644
--- a/pkg/obitools/obiclean/graph.go
+++ b/pkg/obitools/obiclean/graph.go
@@ -17,12 +17,35 @@ import (
 )
 
 type Ratio struct {
+	Sample string
 	From   int
 	To     int
+	CFrom  int
+	CTo    int
 	Pos    int
 	Length int
 }
 
+type Edge struct {
+	Father  int
+	From    byte
+	To      byte
+	Pos     int
+	NucPair int
+	Dist    int
+}
+
+func makeEdge(father, dist, pos int, from, to byte) Edge {
+	return Edge{
+		Father:  father,
+		Dist:    dist,
+		Pos:     pos,
+		From:    from,
+		To:      to,
+		NucPair: nucPair(from, to),
+	}
+}
+
 func abs(x int) int {
 	if x < 0 {
 		return -x
@@ -74,11 +97,19 @@ func EmpiricalDistCsv(filename string, data [][]Ratio) {
 
 	bar := progressbar.NewOptions(len(data), pbopt...)
 
-	fmt.Fprintln(file, "From,To,Count_from,Count_to,Position,length")
+	fmt.Fprintln(file, "Sample,From,To,Weight_from,Weight_to,Count_from,Count_to,Position,length")
 	for code, dist := range data {
 		a1, a2 := intToNucPair(code)
 		for _, ratio := range dist {
-			fmt.Fprintf(file, "%c,%c,%d,%d,%d,%d\n", a1, a2, ratio.From, ratio.To, ratio.Pos, ratio.Length)
+			fmt.Fprintf(file, "%s,%c,%c,%d,%d,%d,%d,%d,%d\n",
+				ratio.Sample,
+				a1, a2,
+				ratio.From,
+				ratio.To,
+				ratio.CFrom,
+				ratio.CTo,
+				ratio.Pos,
+				ratio.Length)
 		}
 		bar.Add(1)
 	}
@@ -94,11 +125,11 @@ func Gml(seqs *[]*seqPCR, sample string, statThreshold int) string {
 		comment "Obiclean graph for sample {{ Name }}"
 		directed 1
 		{{range $index, $data:= .}}
-		{{ if or $data.Fathers (gt $data.SonCount 0)}}
+		{{ if or $data.Edges (gt $data.SonCount 0)}}
 	node [ id {{$index}} 
 			graphics [
 				type "{{ Shape $data.Count }}"
-				fill "{{ if and (gt $data.SonCount 0) (not $data.Fathers)}}#0000FF{{  else }}#00FF00{{ end }}"
+				fill "{{ if and (gt $data.SonCount 0) (not $data.Edges)}}#0000FF{{  else }}#00FF00{{ end }}"
 				h {{ Sqrt $data.Count }}
 				w {{ Sqrt $data.Count }}
 			]
@@ -108,11 +139,11 @@ func Gml(seqs *[]*seqPCR, sample string, statThreshold int) string {
 		 {{ end }}
 
 		 {{range $index, $data:= .}}
-				{{range $i, $father:= $data.Fathers}}
+				{{range $i, $edge:= $data.Edges}}
 	edge [ source {{$index}} 
-	       target {{$father}} 
-		   color "{{ if gt (index $data.Dist $i) 1 }}#FF0000{{  else }}#00FF00{{ end }}"
-		   label "{{(index $data.Dist $i)}}"
+	       target {{$edge.Father}} 
+		   color "{{ if gt (index $data.Edges $i).Dist 1 }}#FF0000{{  else }}#00FF00{{ end }}"
+		   label "{{(index $data.Edges $i).Dist}}"
 		   ]
 				{{ end }}
 				{{ end }}
@@ -226,51 +257,83 @@ func intToNucPair(code int) (a, b byte) {
 	return decode[c1], decode[c2]
 }
 
-func buildSamplePairs(seqs *[]*seqPCR, minStatRatio int, workers int) ([][]Ratio, int) {
+func reweightSequences(seqs *[]*seqPCR) {
+
+	for _, node := range *seqs {
+		node.Weight = node.Count
+	}
+
+	//var rfunc func(*seqPCR)
+
+	rfunc := func(node *seqPCR) {
+		node.AddedSons=0
+		nedges := len(node.Edges)
+		if nedges > 0 {
+			swf := 0.0
+
+			for k := 0; k < nedges; k++ {
+				swf += float64((*seqs)[node.Edges[k].Father].Count)
+			}
+
+			for k := 0; k < nedges; k++ {
+				father := (*seqs)[node.Edges[k].Father]
+				father.Weight += int(math.Round(float64(node.Weight) * float64(father.Count) / swf))
+				father.AddedSons++
+				// log.Println(father.AddedSons, father.SonCount)
+			}
+
+		}
+	}
+
+	for _, node := range *seqs {
+		if node.SonCount == 0 {
+			rfunc(node)
+		}
+	}
+
+	for done := true; done; {
+		done = false
+		for _, node := range *seqs {
+			if node.SonCount > 0 && node.SonCount == node.AddedSons {
+				// log.Println(node.AddedSons, node.SonCount)
+				rfunc(node)
+				done = true
+			}
+		}
+	}
+}
+
+func buildSamplePairs(seqs *[]*seqPCR, workers int) int {
 	nseq := len(*seqs)
 	running := sync.WaitGroup{}
 
-	linePairs := func(i int) [][]Ratio {
+	linePairs := func(i int) {
 
-		ratio := make([][]Ratio, 25)
 		son := (*seqs)[i]
 
 		for j := i + 1; j < nseq; j++ {
 			father := (*seqs)[j]
 			d, pos, a1, a2 := obialign.D1Or0(son.Sequence, father.Sequence)
 			if d > 0 {
-				son.Fathers = append(son.Fathers, j)
-				son.Dist = append(son.Dist, d)
+				son.Edges = append(son.Edges, makeEdge(j, d, pos, a1, a2))
 				father.SonCount++
 
-				if father.Count > minStatRatio {
-					n := nucPair(a1, a2)
-					ratio[n] = append(ratio[n], Ratio{father.Count, son.Count, pos, father.Sequence.Length()})
-				}
 			}
 		}
 
-		return ratio
 	}
 
 	lineChan := make(chan int)
-	idxChan := make(chan [][]Ratio)
 
 	ff := func() {
 		for i := range lineChan {
-			idxChan <- linePairs(i)
+			linePairs(i)
 		}
-
 		running.Done()
 	}
 
 	running.Add(workers)
 
-	go func() {
-		running.Wait()
-		close(idxChan)
-	}()
-
 	for i := 0; i < workers; i++ {
 		go ff()
 	}
@@ -283,15 +346,12 @@ func buildSamplePairs(seqs *[]*seqPCR, minStatRatio int, workers int) ([][]Ratio
 	}()
 
 	np := nseq * (nseq - 1) / 2
-	ratio := make([][]Ratio, 25)
-	for data := range idxChan {
-		for i, r := range data {
-			ratio[i] = append(ratio[i], r...)
-		}
 
-	}
+	running.Wait()
 
-	return ratio, np
+	reweightSequences(seqs)
+
+	return np
 }
 
 func extendSimilarityGraph(seqs *[]*seqPCR, step int, workers int) int {
@@ -310,8 +370,7 @@ func extendSimilarityGraph(seqs *[]*seqPCR, step int, workers int) int {
 					matrix)
 				d := (lali - lcs)
 				if lcs >= 0 && d <= step && step > 0 {
-					son.Fathers = append(son.Fathers, j)
-					son.Dist = append(son.Dist, d)
+					son.Edges = append(son.Edges, makeEdge(j, d, -1, '-', '-'))
 					father.SonCount++
 					//a, b := minMax((*seqs)[i].Count, (*seqs)[j].Count)
 				}
@@ -340,7 +399,7 @@ func extendSimilarityGraph(seqs *[]*seqPCR, step int, workers int) int {
 
 	go func() {
 		for i := 0; i < nseq; i++ {
-			if len((*seqs)[i].Fathers) == 0 {
+			if len((*seqs)[i].Edges) == 0 {
 				lineChan <- i
 			}
 		}
@@ -354,21 +413,18 @@ func extendSimilarityGraph(seqs *[]*seqPCR, step int, workers int) int {
 
 func FilterGraphOnRatio(seqs *[]*seqPCR, ratio float64) {
 	for _, s1 := range *seqs {
-		c1 := float64(s1.Count)
-		f := s1.Fathers
-		d := s1.Dist
+		c1 := float64(s1.Weight)
+		e := s1.Edges
 		j := 0
-		for i, s2 := range f {
-			f[j] = f[i]
-			d[j] = d[i]
-			if (c1 / float64((*seqs)[s2].Count)) <= math.Pow(ratio, float64(d[i])) {
+		for i, s2 := range e {
+			e[j] = e[i]
+			if (c1 / float64((*seqs)[s2.Father].Weight)) <= math.Pow(ratio, float64(e[i].Dist)) {
 				j++
 			} else {
-				(*seqs)[s2].SonCount--
+				(*seqs)[s2.Father].SonCount--
 			}
 		}
-		s1.Fathers = f[0:j]
-		s1.Dist = d[0:j]
+		s1.Edges = e[0:j]
 	}
 }
 
@@ -384,7 +440,7 @@ func sortSamples(samples map[string]*([]*seqPCR)) {
 }
 
 func ObicleanStatus(seq *seqPCR) string {
-	if len(seq.Fathers) == 0 {
+	if len(seq.Edges) == 0 {
 		if seq.SonCount > 0 {
 			return "h"
 		} else {
@@ -395,8 +451,28 @@ func ObicleanStatus(seq *seqPCR) string {
 	}
 }
 
+func EstimateRatio(samples map[string]*[]*seqPCR, minStatRatio int) [][]Ratio {
+	ratio := make([][]Ratio, 25)
+
+	for name, seqs := range samples {
+
+		for _, seq := range *seqs {
+			for _, edge := range seq.Edges {
+				father := (*seqs)[edge.Father]
+				if father.Weight >= minStatRatio && edge.Dist == 1 {
+					ratio[edge.NucPair] = append(ratio[edge.NucPair], Ratio{name, father.Weight, seq.Weight, father.Count, seq.Count, edge.Pos, father.Sequence.Length()})
+				}
+			}
+
+		}
+	}
+
+	return ratio
+
+}
+
 func BuildSeqGraph(samples map[string]*[]*seqPCR,
-	maxError, minStatRatio, workers int) [][]Ratio {
+	maxError, workers int) {
 
 	sortSamples(samples)
 
@@ -416,13 +492,8 @@ func BuildSeqGraph(samples map[string]*[]*seqPCR,
 	)
 
 	bar := progressbar.NewOptions(npairs, pbopt...)
-	all_ratio := make([][]Ratio, 25)
 	for _, seqs := range samples {
-		ratio, np := buildSamplePairs(seqs, minStatRatio, workers)
-
-		for i, r := range ratio {
-			all_ratio[i] = append(all_ratio[i], r...)
-		}
+		np := buildSamplePairs(seqs, workers)
 
 		bar.Add(np)
 	}
@@ -444,6 +515,4 @@ func BuildSeqGraph(samples map[string]*[]*seqPCR,
 			bar.Add(np)
 		}
 	}
-
-	return all_ratio
 }
diff --git a/pkg/obitools/obiclean/obiclean.go b/pkg/obitools/obiclean/obiclean.go
index b25a075..50afa8d 100644
--- a/pkg/obitools/obiclean/obiclean.go
+++ b/pkg/obitools/obiclean/obiclean.go
@@ -13,11 +13,12 @@ import (
 )
 
 type seqPCR struct {
-	Count    int                 // number of reads associated to a sequence in a PCR
-	Sequence *obiseq.BioSequence // pointer to the corresponding sequence
-	SonCount int
-	Fathers  []int
-	Dist     []int
+	Count     int                 // number of reads associated to a sequence in a PCR
+	Weight    int                 // Number of reads associated to a sequence after clustering
+	Sequence  *obiseq.BioSequence // pointer to the corresponding sequence
+	SonCount  int
+	AddedSons int
+	Edges     []Edge
 }
 
 // buildSamples sorts the sequences by samples
@@ -43,9 +44,10 @@ func buildSamples(dataset obiseq.BioSequenceSlice,
 			}
 
 			*pcr = append(*pcr, &seqPCR{
-				Count:    v,
-				Sequence: s,
-				SonCount: 0,
+				Count:     v,
+				Sequence:  s,
+				SonCount:  0,
+				AddedSons: 0,
 			})
 		}
 	}
@@ -181,6 +183,33 @@ func Status(sequence *obiseq.BioSequence) map[string]string {
 	return obistatus
 }
 
+func Weight(sequence *obiseq.BioSequence) map[string]int {
+	annotation := sequence.Annotations()
+	iobistatus, ok := annotation["obiclean_weight"]
+	var weight map[string]int
+	var err error
+
+	if ok {
+		switch iobistatus := iobistatus.(type) {
+		case map[string]int:
+			weight = iobistatus
+		case map[string]interface{}:
+			weight = make(map[string]int)
+			for k, v := range iobistatus {
+				weight[k], err = goutils.InterfaceToInt(v)
+				if err != nil {
+					log.Panicf("Weight value %v cannnot be casted to an integer value\n", v)
+				}
+			}
+		}
+	} else {
+		weight = make(map[string]int)
+		annotation["obiclean_weight"] = weight
+	}
+
+	return weight
+}
+
 func IOBIClean(itertator obiiter.IBioSequenceBatch) obiiter.IBioSequenceBatch {
 
 	db := itertator.Load()
@@ -191,9 +220,8 @@ func IOBIClean(itertator obiiter.IBioSequenceBatch) obiiter.IBioSequenceBatch {
 
 	log.Infof("Dataset composed of %d samples\n", len(samples))
 
-	all_ratio := BuildSeqGraph(samples,
+	BuildSeqGraph(samples,
 		DistStepMax(),
-		MinCountToEvalMutationRate(),
 		obioptions.CLIParallelWorkers())
 
 	if RatioMax() < 1.0 {
@@ -215,6 +243,7 @@ func IOBIClean(itertator obiiter.IBioSequenceBatch) obiiter.IBioSequenceBatch {
 	}
 
 	if IsSaveRatioTable() {
+		all_ratio := EstimateRatio(samples, MinCountToEvalMutationRate())
 		EmpiricalDistCsv(RatioTableFilename(), all_ratio)
 	}
 
@@ -237,6 +266,9 @@ func IOBIClean(itertator obiiter.IBioSequenceBatch) obiiter.IBioSequenceBatch {
 		for _, pcr := range *seqs {
 			obistatus := Status(pcr.Sequence)
 			obistatus[name] = ObicleanStatus(pcr)
+
+			obiweight := Weight(pcr.Sequence)
+			obiweight[name] = pcr.Weight
 		}
 		bar.Add(1)
 	}