Change obiclean algorithm for a better evaluation of ratio

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) {