diff --git a/hipo4/bank.cpp b/hipo4/bank.cpp
index 89680e7..88175bd 100644
--- a/hipo4/bank.cpp
+++ b/hipo4/bank.cpp
@@ -398,7 +398,7 @@ void    bank::putLong(const char *name, int index, int64_t value){
   int offset = bankSchema.getOffset(item, index, bankRows);
   putLongAt(offset,value);
 }
-
+/*
 hipo::iterator iterator::link(hipo::bank &bank, int row, int column){
     hipo::iterator blink(bank);
     int nrows = bank.getRows();
@@ -407,33 +407,62 @@ hipo::iterator iterator::link(hipo::bank &bank, int row, int column){
     }
     return blink;
 }
-
-hipo::iterator iterator::reduce(std::function<double(hipo::bank&, int)> func, hipo::bank& bank){
-  hipo::iterator it(bank);
-  int nrows = bank.getRows();
-  for(int r = 0; r < nrows; r++){
-    double v = func(bank,r);
-    if(v>0.5) it.add(r);
+*/
+void bank::reduce(std::function<double(hipo::bank&, int)> func, bool doReset){
+  
+  if(doReset==true){
+    bankIterator.reset();
+    int nrows = getRows();
+    for(int r = 0; r < nrows; r++){
+      double v = func(*this,r);
+      if(v>0.5) bankIterator.add(r);
+    }
+  } else {
+    std::vector<int> indx;
+    for(bankIterator.begin();!bankIterator.end(); bankIterator.next()){
+      indx.push_back(bankIterator.index());
+    }
+    bankIterator.reset();
+    int nrows = (int) indx.size();
+    for(int r = 0; r < nrows; r++){
+      double v = func(*this,indx[r]);
+      if(v>0.5) bankIterator.add(indx[r]);
+    }
   }
-  return it;
+  //return it;
 }
 
-hipo::iterator iterator::reduce(hipo::bank &bank, const char *expression){
+void bank::reduce(const char *expression, bool doReset){
   hipo::Parser p(expression);
-
-  int nrows = bank.getRows();
-  int nitems = bank.getSchema().getEntries();
-  hipo::schema &schema = bank.getSchema();
-  hipo::iterator it(bank);
-  for(int k = 0; k < nrows; k++){
-     for(int i = 0; i < nitems; i++){
-       p[schema.getEntryName(i)] = bank.get(i,k);
-     }
-     double value = p.Evaluate();
+  int nrows  = getRows();
+  int nitems = getSchema().getEntries();
+  hipo::schema &schema = getSchema();
+  if(doReset==true){
+    bankIterator.reset();
+    for(int k = 0; k < nrows; k++){
+      for(int i = 0; i < nitems; i++){
+        p[schema.getEntryName(i)] = get(i,k);
+      }
+      double value = p.Evaluate();
+     //printf(" row = %d - value %f\n",k,value);
+      if(value>0.5) bankIterator.add(k);
+    }
+  } else {
+    std::vector<int> indx;
+    for(bankIterator.begin();!bankIterator.end(); bankIterator.next()){
+      indx.push_back(bankIterator.index());
+    }
+    bankIterator.reset();
+    for(int k = 0; k < (int) indx.size(); k++){
+      for(int i = 0; i < nitems; i++){
+        p[schema.getEntryName(i)] = get(i,indx[k]);
+      }
+      double value = p.Evaluate();
      //printf(" row = %d - value %f\n",k,value);
-     if(value>0.5) it.add(k);
+      if(value>0.5) bankIterator.add(indx[k]);
+    }
   }
-  return it;
+  //return it;
 }
 
 void bank::show(){
diff --git a/hipo4/bank.h b/hipo4/bank.h
index 65ebd4d..7322dc3 100644
--- a/hipo4/bank.h
+++ b/hipo4/bank.h
@@ -201,11 +201,31 @@ namespace hipo {
   };
   //typedef std::auto_ptr<hipo::generic_node> node_pointer;
 
+class iterator {
+    private:
+      std::vector<int> rows;
+      decltype(rows)::size_type current_index;
+    public:
+      iterator(){}
+      virtual ~iterator(){}
+      void    reset(){ rows.clear();}
+      void    add(int index){rows.push_back(index);}
+      void    begin(){current_index=0;}
+      bool    next(){
+        current_index++; if(current_index>rows.size()) { 
+          current_index = rows.size(); return false;
+        } return true;
+      }
+      bool   end(){return current_index>=rows.size();}
+      int    index(){ return rows[current_index];}
+      void   show(){ for(const auto& row : rows) printf("%5d ",row); printf("\n");}
+};
     class bank : public hipo::structure {
 
     private:
 
-      hipo::schema  bankSchema;
+      hipo::schema    bankSchema;
+      hipo::iterator  bankIterator;
       int           bankRows{-1};
 
     protected:
@@ -234,7 +254,7 @@ namespace hipo {
         //void show();
 
         hipo::schema  &getSchema() { return bankSchema;}
-
+        hipo::iterator &getIterator(){ return bankIterator;}
         int    getRows()  const noexcept{ return bankRows;}
         void   setRows(   int rows);
         int    getInt(    int item, int index) const noexcept;
@@ -298,7 +318,8 @@ namespace hipo {
               printf("---> error(put) : unknown type for [%s] type = %d\n", bankSchema.getEntryName(item).c_str(), type);
           }
         }
-     
+        void reduce(std::function<double(hipo::bank&, int)> func, bool doReset);
+        void reduce(const char *expression, bool doReset);
         void    show() override;
         void    reset();
         //virtual  void notify(){ };
@@ -307,6 +328,7 @@ namespace hipo {
 
   };
 
+/*
   class iterator {
     private:
       hipo::bank  &ib;
@@ -339,6 +361,7 @@ namespace hipo {
       static hipo::iterator reduce(std::function<double(hipo::bank&, int)> func, hipo::bank& bank);
       static hipo::iterator reduce(hipo::bank &bank, const char *expression);
   };
+  */
     /////////////////////////////////////
     //inlined getters