diff --git a/samoa-instances/src/main/java/org/apache/samoa/instances/ArffLoader.java b/samoa-instances/src/main/java/org/apache/samoa/instances/ArffLoader.java
index a25dc62..dd82eda 100644
--- a/samoa-instances/src/main/java/org/apache/samoa/instances/ArffLoader.java
+++ b/samoa-instances/src/main/java/org/apache/samoa/instances/ArffLoader.java
@@ -29,39 +29,95 @@
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
-/**
- * @author abifet
- */
 public class ArffLoader implements Loader {
 
+  /**
+   * The instance information.
+   */
   protected InstanceInformation instanceInformation;
 
-  transient protected StreamTokenizer streamTokenizer;
+  protected InstancesHeader streamHeader;
 
-  protected Reader reader;
+  /**
+   * The stream tokenizer.
+   */
+  protected transient StreamTokenizer streamTokenizer;
 
-  protected int size;
-
-  protected int classAttribute;
-
-  public ArffLoader() {
-  }
-
+  /**
+   * Instantiates a new arff loader.
+   *
+   * @param reader the reader
+   * @param size the size
+   * @param classAttribute the class attribute
+   */
   public ArffLoader(Reader reader, int size, int classAttribute) {
-    this.reader = reader;
-    this.size = size;
-    this.classAttribute = classAttribute;
-    initStreamTokenizer(reader);
+    // size is not used
+    this(reader);
+    if (classAttribute < 0) {
+      this.instanceInformation.setClassIndex(this.instanceInformation.numAttributes() - 1);
+      //System.out.print(this.instanceInformation.classIndex());
+    } else if (classAttribute > 0) {
+      this.instanceInformation.setClassIndex(classAttribute - 1);
+    }
   }
 
+  protected Range range;
+
+  /**
+   * Instantiates a new arff loader.
+   *
+   * @param reader the reader
+   */
+  public ArffLoader(Reader reader) {
+    this(reader, null);
+  }
+
+  /**
+   * Instantiates a new arff loader.
+   *
+   * @param reader the reader
+   * @param range
+   */
+  public ArffLoader(Reader reader, Range range) {
+    this.range = range;
+    BufferedReader br = new BufferedReader(reader);
+
+    //Init streamTokenizer
+    streamTokenizer = new StreamTokenizer(br);
+    streamTokenizer.resetSyntax();
+    streamTokenizer.whitespaceChars(0, ' ');
+    streamTokenizer.wordChars(' ' + 1, '\u00FF');
+    streamTokenizer.whitespaceChars(',', ',');
+    streamTokenizer.commentChar('%');
+    streamTokenizer.quoteChar('"');
+    streamTokenizer.quoteChar('\'');
+    streamTokenizer.ordinaryChar('{');
+    streamTokenizer.ordinaryChar('}');
+    streamTokenizer.eolIsSignificant(true);
+
+    this.instanceInformation = this.getHeader();
+
+    if (range != null) { //is MultiLabel
+      this.instanceInformation.setRangeOutputIndices(range);
+    }
+
+  }
+
+  /**
+   * Gets the structure.
+   *
+   * @return the structure
+   */
   public InstanceInformation getStructure() {
     return this.instanceInformation;
   }
 
-  public Instance readInstance(Reader reader) {
-    if (streamTokenizer == null) {
-      initStreamTokenizer(reader);
-    }
+  /**
+   * Reads instance. It detects if it is dense or sparse.
+   *
+   * @return the instance
+   */
+  public Instance readInstance() {
     while (streamTokenizer.ttype == StreamTokenizer.TT_EOL) {
       try {
         streamTokenizer.nextToken();
@@ -78,94 +134,121 @@
 
   }
 
+  /**
+   * Reads instance. It detects if it is dense or sparse.
+   *
+   * @return the instance
+   */
+  public Instance readInstance(Reader reader) {
+    while (streamTokenizer.ttype == StreamTokenizer.TT_EOL) {
+      try {
+        streamTokenizer.nextToken();
+      } catch (IOException ex) {
+        Logger.getLogger(ArffLoader.class.getName()).log(Level.SEVERE, null, ex);
+      }
+    }
+    if (streamTokenizer.ttype == '{') {
+      return readInstanceSparse();
+      // return readDenseInstanceSparse();
+    } else {
+      return readInstanceDense();
+    }
+
+  }
+
+  /**
+   * Reads a dense instance from the file.
+   *
+   * @return the instance
+   */
   public Instance readInstanceDense() {
-    Instance instance = new DenseInstance(this.instanceInformation.numAttributes() + 1);
-    // System.out.println(this.instanceInformation.numAttributes());
+    Instance instance = newDenseInstance(this.instanceInformation.numAttributes());
+    //System.out.println(this.instanceInformation.numAttributes());
     int numAttribute = 0;
     try {
       while (numAttribute == 0 && streamTokenizer.ttype != StreamTokenizer.TT_EOF) {
-        // For each line
+        //For each line
         while (streamTokenizer.ttype != StreamTokenizer.TT_EOL
             && streamTokenizer.ttype != StreamTokenizer.TT_EOF) {
-          // For each item
+          //For each item
           if (streamTokenizer.ttype == StreamTokenizer.TT_NUMBER) {
-            // System.out.println(streamTokenizer.nval + "Num ");
-            this.setValue(instance, numAttribute, streamTokenizer.nval, true);
-            //numAttribute++;
+            //System.out.println(streamTokenizer.nval + "Num ");
+            instance.setValue(numAttribute, streamTokenizer.nval);//this.setValue(instance, numAttribute, streamTokenizer.nval, true);
+            ++numAttribute;
 
-          } else if (streamTokenizer.sval != null && (
-              streamTokenizer.ttype == StreamTokenizer.TT_WORD
-                  || streamTokenizer.ttype == 34 || streamTokenizer.ttype == 39)) {
-            // System.out.println(streamTokenizer.sval + "Str");
-            boolean isNumeric = attributes.get(numAttribute).isNumeric();
+          } else if (streamTokenizer.sval != null && (streamTokenizer.ttype == StreamTokenizer.TT_WORD
+              || streamTokenizer.ttype == 34 || streamTokenizer.ttype == 39)) {
+            //System.out.println(streamTokenizer.sval + "Str");
+            boolean isNumeric = this.auxAttributes.get(numAttribute).isNumeric();
             double value;
             if ("?".equals(streamTokenizer.sval)) {
-              value = Double.NaN; // Utils.missingValue();
+              value = Double.NaN; //Utils.missingValue();
             } else if (isNumeric == true) {
               value = Double.valueOf(streamTokenizer.sval).doubleValue();
             } else {
-              value = this.instanceInformation.attribute(numAttribute).indexOfValue(
-                  streamTokenizer.sval);
+              value = this.auxAttributes.get(numAttribute).indexOfValue(streamTokenizer.sval);
             }
 
-            this.setValue(instance, numAttribute, value, isNumeric);
-            //numAttribute++;
+            instance.setValue(numAttribute,value);//this.setValue(instance, numAttribute, value, isNumeric);
+            ++numAttribute;
           }
-          numAttribute++;
           streamTokenizer.nextToken();
         }
         streamTokenizer.nextToken();
-        // System.out.println("EOL");
+        //System.out.println("EOL");
       }
 
     } catch (IOException ex) {
       Logger.getLogger(ArffLoader.class.getName()).log(Level.SEVERE, null, ex);
     }
-    //System.out.println(instance);
     return (numAttribute > 0) ? instance : null;
   }
 
-  private void setValue(Instance instance, int numAttribute, double value, boolean isNumber) {
+  protected void setValue(Instance instance, int numAttribute, double value, boolean isNumber) {
     double valueAttribute;
-    if (this.instanceInformation.attribute(numAttribute).isNominal) {
-      valueAttribute = value;
-      //this.instanceInformation.attribute(numAttribute).indexOfValue(Double.toString(value));
-      // System.out.println(value +"/"+valueAttribute+" ");
+
+    if (isNumber && this.auxAttributes.get(numAttribute).isNominal) {
+      valueAttribute = value;//this.auxAttributes.get(numAttribute).indexOfValue(Double.toString(value));
+      //System.out.println(value +"/"+valueAttribute+" ");
 
     } else {
       valueAttribute = value;
-      // System.out.println(value +"/"+valueAttribute+" ");
+      //System.out.println(value +"/"+valueAttribute+" ");
     }
     if (this.instanceInformation.classIndex() == numAttribute) {
-      instance.setClassValue(valueAttribute);
-      // System.out.println(value
-      // +"<"+this.instanceInformation.classIndex()+">");
+      setClassValue(instance, valueAttribute);
+      //System.out.println(value +"<"+this.instanceInformation.classIndex()+">");
     } else {
+      //if(numAttribute>this.instanceInformation.classIndex())
+      //	numAttribute--;
       instance.setValue(numAttribute, valueAttribute);
     }
   }
 
+  /**
+   * Reads a sparse instance.
+   *
+   * @return the instance
+   */
   private Instance readInstanceSparse() {
-    // Return a Sparse Instance
-    Instance instance = new SparseInstance(1.0, null); // (this.instanceInformation.numAttributes()
-    // + 1);
-    // System.out.println(this.instanceInformation.numAttributes());
+    //Return a Sparse Instance
+    Instance instance = newSparseInstance(1.0); //, null); //(this.instanceInformation.numAttributes() + 1);
+    //System.out.println(this.instanceInformation.numAttributes());
     int numAttribute;
     ArrayList<Double> attributeValues = new ArrayList<Double>();
     List<Integer> indexValues = new ArrayList<Integer>();
     try {
-      // while (streamTokenizer.ttype != StreamTokenizer.TT_EOF) {
+      //while (streamTokenizer.ttype != StreamTokenizer.TT_EOF) {
       streamTokenizer.nextToken(); // Remove the '{' char
-      // For each line
+      //For each line
       while (streamTokenizer.ttype != StreamTokenizer.TT_EOL
           && streamTokenizer.ttype != StreamTokenizer.TT_EOF) {
         while (streamTokenizer.ttype != '}') {
-          // For each item
-          // streamTokenizer.nextToken();
-          // while (streamTokenizer.ttype != '}'){
-          // System.out.println(streamTokenizer.nval +"-"+
-          // streamTokenizer.sval);
-          // numAttribute = (int) streamTokenizer.nval;
+          //For each item
+          //streamTokenizer.nextToken();
+          //while (streamTokenizer.ttype != '}'){
+          //System.out.println(streamTokenizer.nval +"-"+ streamTokenizer.sval);
+          //numAttribute = (int) streamTokenizer.nval;
           if (streamTokenizer.ttype == StreamTokenizer.TT_NUMBER) {
             numAttribute = (int) streamTokenizer.nval;
           } else {
@@ -174,32 +257,26 @@
           streamTokenizer.nextToken();
 
           if (streamTokenizer.ttype == StreamTokenizer.TT_NUMBER) {
-            // System.out.print(streamTokenizer.nval + " ");
-            this.setSparseValue(instance, indexValues, attributeValues, numAttribute,
-                streamTokenizer.nval, true);
-            // numAttribute++;
+            //System.out.print(streamTokenizer.nval + " ");
+            this.setSparseValue(instance, indexValues, attributeValues, numAttribute, streamTokenizer.nval, true);
+            //numAttribute++;
 
-          } else if (streamTokenizer.sval != null && (
-              streamTokenizer.ttype == StreamTokenizer.TT_WORD
-              || streamTokenizer.ttype == 34)) {
-            // System.out.print(streamTokenizer.sval + "-");
-            if (attributes.get(numAttribute).isNumeric()) {
-              this.setSparseValue(instance, indexValues, attributeValues, numAttribute,
-                  Double.valueOf(streamTokenizer.sval).doubleValue(), true);
+          } else if (streamTokenizer.sval != null && (streamTokenizer.ttype == StreamTokenizer.TT_WORD
+              || streamTokenizer.ttype == 34 || streamTokenizer.ttype == 39)) {
+            //System.out.print(streamTokenizer.sval + "-");
+            if (this.auxAttributes.get(numAttribute).isNumeric()) {
+              this.setSparseValue(instance, indexValues, attributeValues, numAttribute, Double.valueOf(streamTokenizer.sval).doubleValue(), true);
             } else {
-              this.setSparseValue(instance, indexValues, attributeValues, numAttribute,
-                  this.instanceInformation
-                      .attribute(numAttribute).indexOfValue(streamTokenizer.sval),
-                  false);
+              this.setSparseValue(instance, indexValues, attributeValues, numAttribute, this.auxAttributes.get(numAttribute).indexOfValue(streamTokenizer.sval), false);
             }
           }
           streamTokenizer.nextToken();
         }
-        streamTokenizer.nextToken(); // Remove the '}' char
+        streamTokenizer.nextToken(); //Remove the '}' char
       }
       streamTokenizer.nextToken();
-      // System.out.println("EOL");
-      // }
+      //System.out.println("EOL");
+      //}
 
     } catch (IOException ex) {
       Logger.getLogger(ArffLoader.class.getName()).log(Level.SEVERE, null, ex);
@@ -210,78 +287,74 @@
       arrayIndexValues[i] = indexValues.get(i).intValue();
       arrayAttributeValues[i] = attributeValues.get(i).doubleValue();
     }
-    instance.addSparseValues(arrayIndexValues, arrayAttributeValues,
-        this.instanceInformation.numAttributes());
+    instance.addSparseValues(arrayIndexValues, arrayAttributeValues, this.instanceInformation.numAttributes());
     return instance;
 
   }
 
-  private void setSparseValue(Instance instance, List<Integer> indexValues,
-      List<Double> attributeValues,
-      int numAttribute, double value, boolean isNumber) {
+  private void setSparseValue(Instance instance, List<Integer> indexValues, List<Double> attributeValues, int numAttribute, double value, boolean isNumber) {
     double valueAttribute;
-    if (isNumber && this.instanceInformation.attribute(numAttribute).isNominal) {
-      valueAttribute =
-          this.instanceInformation.attribute(numAttribute).indexOfValue(Double.toString(value));
+    if (isNumber && this.auxAttributes.get(numAttribute).isNominal) {
+      valueAttribute = this.auxAttributes.get(numAttribute).indexOfValue(Double.toString(value));
     } else {
       valueAttribute = value;
     }
-    if (this.instanceInformation.classIndex() == numAttribute) {
-      instance.setClassValue(valueAttribute);
-    } else {
-      // instance.setValue(numAttribute, valueAttribute);
-      indexValues.add(numAttribute);
-      attributeValues.add(valueAttribute);
-    }
-    // System.out.println(numAttribute+":"+valueAttribute+","+this.instanceInformation.classIndex()+","+value);
+    //if (this.instanceInformation.classIndex() == numAttribute) {
+    //    setClassValue(instance, valueAttribute);
+    //} else {
+    //instance.setValue(numAttribute, valueAttribute);
+    indexValues.add(numAttribute);
+    attributeValues.add(valueAttribute);
+    //}
+    //System.out.println(numAttribute+":"+valueAttribute+","+this.instanceInformation.classIndex()+","+value);
   }
 
+  /**
+   * Reads an instance sparse and returns a dense one.
+   *
+   * @return the instance
+   */
   private Instance readDenseInstanceSparse() {
-    // Returns a dense instance
-    Instance instance = new DenseInstance(this.instanceInformation.numAttributes() + 1);
-    // System.out.println(this.instanceInformation.numAttributes());
+    //Returns a dense instance
+    Instance instance = newDenseInstance(this.instanceInformation.numAttributes());
+    //System.out.println(this.instanceInformation.numAttributes());
     int numAttribute;
     try {
-      // while (streamTokenizer.ttype != StreamTokenizer.TT_EOF) {
+      //while (streamTokenizer.ttype != StreamTokenizer.TT_EOF) {
       streamTokenizer.nextToken(); // Remove the '{' char
-      // For each line
+      //For each line
       while (streamTokenizer.ttype != StreamTokenizer.TT_EOL
           && streamTokenizer.ttype != StreamTokenizer.TT_EOF) {
         while (streamTokenizer.ttype != '}') {
-          // For each item
-          // streamTokenizer.nextToken();
-          // while (streamTokenizer.ttype != '}'){
-          // System.out.print(streamTokenizer.nval+":");
+          //For each item
+          //streamTokenizer.nextToken();
+          //while (streamTokenizer.ttype != '}'){
+          //System.out.print(streamTokenizer.nval+":");
           numAttribute = (int) streamTokenizer.nval;
           streamTokenizer.nextToken();
 
           if (streamTokenizer.ttype == StreamTokenizer.TT_NUMBER) {
-            // System.out.print(streamTokenizer.nval + " ");
-            this.setValue(instance, numAttribute, streamTokenizer.nval, true);
-            // numAttribute++;
+            //System.out.print(streamTokenizer.nval + " ");
+            instance.setValue(numAttribute, streamTokenizer.nval);//this.setValue(instance, numAttribute, streamTokenizer.nval, true);
+            //numAttribute++;
 
-          } else if (streamTokenizer.sval != null && (
-              streamTokenizer.ttype == StreamTokenizer.TT_WORD
+          } else if (streamTokenizer.sval != null && (streamTokenizer.ttype == StreamTokenizer.TT_WORD
               || streamTokenizer.ttype == 34)) {
-            // System.out.print(streamTokenizer.sval +
-            // "/"+this.instanceInformation.attribute(numAttribute).indexOfValue(streamTokenizer.sval)+" ");
-            if (attributes.get(numAttribute).isNumeric()) {
-              this.setValue(instance, numAttribute,
-                  Double.valueOf(streamTokenizer.sval).doubleValue(), true);
+            //System.out.print(streamTokenizer.sval + "/"+this.auxAttributes.get(numAttribute).indexOfValue(streamTokenizer.sval)+" ");
+            if (this.auxAttributes.get(numAttribute).isNumeric()) {
+              instance.setValue(numAttribute, Double.valueOf(streamTokenizer.sval).doubleValue());//this.setValue(instance, numAttribute, Double.valueOf(streamTokenizer.sval).doubleValue(), true);
             } else {
-              this.setValue(instance, numAttribute,
-                  this.instanceInformation.attribute(numAttribute)
-                      .indexOfValue(streamTokenizer.sval), false);
-              // numAttribute++;
+              instance.setValue(numAttribute, this.auxAttributes.get(numAttribute).indexOfValue(streamTokenizer.sval));//this.setValue(instance, numAttribute, this.auxAttributes.get(numAttribute).indexOfValue(streamTokenizer.sval), false);
+              //numAttribute++;
             }
           }
           streamTokenizer.nextToken();
         }
-        streamTokenizer.nextToken(); // Remove the '}' char
+        streamTokenizer.nextToken(); //Remove the '}' char
       }
       streamTokenizer.nextToken();
-      // System.out.println("EOL");
-      // }
+      //System.out.println("EOL");
+      //}
 
     } catch (IOException ex) {
       Logger.getLogger(ArffLoader.class.getName()).log(Level.SEVERE, null, ex);
@@ -289,30 +362,37 @@
     return instance;
   }
 
-  protected List<Attribute> attributes;
+  //protected List<Attribute> inputAttributes;
+  // protected List<Attribute> outputAttributes;
+
+  protected List<Attribute> auxAttributes;
 
   private InstanceInformation getHeader() {
-
+    //commented JD
+    //this.range.setUpper(10000); //TO DO: Create a new range object with isInRange that does not need the upper limit
     String relation = "file stream";
-    // System.out.println("RELATION " + relation);
-    attributes = new ArrayList<Attribute>();
+    //System.out.println("RELATION " + relation);
+    //inputAttributes = new ArrayList<Attribute>();
+    //outputAttributes = new ArrayList<Attribute>();
+    //ArrayList<Attribute>
+    auxAttributes = new ArrayList<Attribute>();//JD
+    int numAttributes = 0;
     try {
       streamTokenizer.nextToken();
       while (streamTokenizer.ttype != StreamTokenizer.TT_EOF) {
-        // For each line
-        // if (streamTokenizer.ttype == '@') {
-        if (streamTokenizer.ttype == StreamTokenizer.TT_WORD
-            && streamTokenizer.sval.startsWith("@") == true) {
-          // streamTokenizer.nextToken();
+        //For each line
+        //if (streamTokenizer.ttype == '@') {
+        if (streamTokenizer.ttype == StreamTokenizer.TT_WORD && streamTokenizer.sval.startsWith("@") == true) {
+          //streamTokenizer.nextToken();
           String token = streamTokenizer.sval.toUpperCase();
           if (token.startsWith("@RELATION")) {
             streamTokenizer.nextToken();
             relation = streamTokenizer.sval;
-            // System.out.println("RELATION " + relation);
+            //  System.out.println("RELATION " + relation);
           } else if (token.startsWith("@ATTRIBUTE")) {
             streamTokenizer.nextToken();
             String name = streamTokenizer.sval;
-            // System.out.println("* " + name);
+            //System.out.println("* " + name);
             if (name == null) {
               name = Double.toString(streamTokenizer.nval);
             }
@@ -320,81 +400,95 @@
             String type = streamTokenizer.sval;
             // System.out.println("* " + name + ":" + type + " ");
             if (streamTokenizer.ttype == '{') {
-              parseDoubleBrackests(name);
-            } else if (streamTokenizer.ttype == 10) {//for the buggy non-formal input arff file
               streamTokenizer.nextToken();
-              if (streamTokenizer.ttype == '{') {
-                parseDoubleBrackests(name);
+              List<String> attributeLabels = new ArrayList<String>();
+              while (streamTokenizer.ttype != '}') {
+
+                if (streamTokenizer.sval != null) {
+                  attributeLabels.add(streamTokenizer.sval);
+                  // System.out.print(streamTokenizer.sval + ",");
+                } else {
+                  attributeLabels.add(Double.toString(streamTokenizer.nval));
+                  //System.out.print(streamTokenizer.nval + ",");
+                }
+
+                streamTokenizer.nextToken();
               }
+              // System.out.println();
+              //attributes.add(new Attribute(name, attributeLabels));
+              //commented JD
+              /* if (this.range.isInRange(numAttribute)) {
+                             outputAttributes.add(new Attribute(name, attributeLabels));
+                             } else {
+                             inputAttributes.add(new Attribute(name, attributeLabels));
+                             }*/
+              auxAttributes.add(new Attribute(name, attributeLabels));
+              ++numAttributes;
             } else {
               // Add attribute
-              attributes.add(new Attribute(name));
+              //commented JD
+              /*if (this.range.isInRange(numAttribute)) {
+                             outputAttributes.add(new Attribute(name));
+                             } else {
+                             inputAttributes.add(new Attribute(name));
+                             }*/
+              auxAttributes.add(new Attribute(name));
+              ++numAttributes;
             }
 
           } else if (token.startsWith("@DATA")) {
-            // System.out.print("END");
+            //System.out.print("END");
             streamTokenizer.nextToken();
             break;
           }
         }
         streamTokenizer.nextToken();
       }
+      if (range != null) {
+        this.range.setUpper(numAttributes);
+      }
+      /*if (range==null) //is single-target. All instances should go to inputAtrributes (see setClassIndex(int) from InstanceInformation )
+             inputAttributes=auxAttributes;
+             else//is multi-target
+             {
+             this.range.setUpper(numAttribute);
+             for (int i=0; i<auxAttributes.size();i++)
+             {
+             //if (this.range.isInRange(i))
+             //	outputAttributes.add(auxAttributes.get(i));
+             //else
+             inputAttributes.add(auxAttributes.get(i));
+
+             }
+             }*/
 
     } catch (IOException ex) {
       Logger.getLogger(ArffLoader.class.getName()).log(Level.SEVERE, null, ex);
     }
-    return new InstanceInformation(relation, attributes);
+    // this.range.setUpper(inputAttributes.size()+outputAttributes.size());
+    return new InstanceInformation(relation, auxAttributes);
   }
 
-  private void parseDoubleBrackests(String name) throws IOException {
-
-    streamTokenizer.nextToken();
-    List<String> attributeLabels = new ArrayList<String>();
-    while (streamTokenizer.ttype != '}') {
-
-      if (streamTokenizer.sval != null) {
-        attributeLabels.add(streamTokenizer.sval);
-        // System.out.print(streamTokenizer.sval + ",");
-      } else {
-        attributeLabels.add(Double.toString(streamTokenizer.nval));
-        // System.out.print(streamTokenizer.nval + ",");
-      }
-
-      streamTokenizer.nextToken();
-    }
-    // System.out.println();
-    attributes.add(new Attribute(name, attributeLabels));
-
+  protected Instance newSparseInstance(double d, double[] res) {
+    Instance inst = new SparseInstance(d, res); //is it dense?
+    //inst.setInstanceInformation(this.instanceInformation);
+    return inst;
   }
 
-  private void initStreamTokenizer(Reader reader) {
-    BufferedReader br = new BufferedReader(reader);
-
-    // Init streamTokenizer
-    streamTokenizer = new StreamTokenizer(br);
-
-    streamTokenizer.resetSyntax();
-    streamTokenizer.whitespaceChars(0, ' ');
-    streamTokenizer.wordChars(' ' + 1, '\u00FF');
-    streamTokenizer.whitespaceChars(',', ',');
-    streamTokenizer.commentChar('%');
-    streamTokenizer.quoteChar('"');
-    streamTokenizer.quoteChar('\'');
-    streamTokenizer.ordinaryChar('{');
-    streamTokenizer.ordinaryChar('}');
-    streamTokenizer.eolIsSignificant(true);
-
-    this.instanceInformation = this.getHeader();
-    if (classAttribute < 0) {
-      this.instanceInformation.setClassIndex(this.instanceInformation.numAttributes() - 1);
-      // System.out.print(this.instanceInformation.classIndex());
-    } else if (classAttribute > 0) {
-      this.instanceInformation.setClassIndex(classAttribute - 1);
-    }
+  protected Instance newSparseInstance(double d) {
+    Instance inst = new SparseInstance(d);
+    //inst.setInstanceInformation(this.instanceInformation);
+    return inst;
   }
 
-  @Override
-  public Instance readInstance() {
-    return readInstance(this.reader);
+  protected Instance newDenseInstance(int numberAttributes) {
+    Instance inst = new DenseInstance(numberAttributes);
+    //inst.setInstanceInformation(this.instanceInformation);
+    return inst;
   }
+
+  private void setClassValue(Instance instance, double valueAttribute) {
+    instance.setValue(this.instanceInformation.classIndex(), valueAttribute);
+  }
+
 }
diff --git a/samoa-instances/src/main/java/org/apache/samoa/instances/Attribute.java b/samoa-instances/src/main/java/org/apache/samoa/instances/Attribute.java
index f14e6c3..128ace7 100644
--- a/samoa-instances/src/main/java/org/apache/samoa/instances/Attribute.java
+++ b/samoa-instances/src/main/java/org/apache/samoa/instances/Attribute.java
@@ -1,7 +1,3 @@
-/*
- * To change this template, choose Tools | Templates
- * and open the template in the editor.
- */
 package org.apache.samoa.instances;
 
 /*
@@ -28,53 +24,79 @@
 import java.text.SimpleDateFormat;
 import java.util.*;
 
-/**
- * @author abifet
- */
 public class Attribute implements Serializable {
 
-  public static final String ARFF_ATTRIBUTE = "@attribute";
-  public static final String ARFF_ATTRIBUTE_NUMERIC = "numeric";
-  public static final String ARFF_ATTRIBUTE_NOMINAL = "nominal";
-  public static final String ARFF_ATTRIBUTE_DATE = "date";
+  /** The keyword used to denote the start of an arff attribute declaration */
+  public final static String ARFF_ATTRIBUTE = "@attribute";
+
+  /** A keyword used to denote a numeric attribute */
+  public final static String ARFF_ATTRIBUTE_INTEGER = "integer";
+
+  /** A keyword used to denote a numeric attribute */
+  public final static String ARFF_ATTRIBUTE_REAL = "real";
+
+  /** A keyword used to denote a numeric attribute */
+  public final static String ARFF_ATTRIBUTE_NUMERIC = "numeric";
+
+  /** The keyword used to denote a string attribute */
+  public final static String ARFF_ATTRIBUTE_STRING = "string";
+
+  /** The keyword used to denote a date attribute */
+  public final static String ARFF_ATTRIBUTE_DATE = "date";
+
+  /** The keyword used to denote a relation-valued attribute */
+  public final static String ARFF_ATTRIBUTE_RELATIONAL = "relational";
+
+  /** The keyword used to denote the end of the declaration of a subrelation */
+  public final static String ARFF_END_SUBRELATION = "@end";
+
+  /** Strings longer than this will be stored compressed. */
+  private static final int STRING_COMPRESS_THRESHOLD = 200;
 
   /**
-   *
+   * The is nominal.
    */
   protected boolean isNominal;
+
   /**
-   *
+   * The is numeric.
    */
   protected boolean isNumeric;
+
   /**
-   *
+   * The is date.
    */
   protected boolean isDate;
+
+  /** 
+   * Date format specification for date attributes 
+   */
+  protected SimpleDateFormat m_DateFormat;
+
   /**
-   *
+   * The name.
    */
   protected String name;
+
   /**
-   *
+   * The attribute values.
    */
   protected List<String> attributeValues;
 
   /**
+   * Gets the attribute values.
    *
-   * @return
+   * @return the attribute values
    */
   public List<String> getAttributeValues() {
     return attributeValues;
   }
 
-  /**
-   *
-   */
-  protected int index;
 
   /**
+   * Instantiates a new attribute.
    *
-   * @param string
+   * @param string the string
    */
   public Attribute(String string) {
     this.name = string;
@@ -82,9 +104,10 @@
   }
 
   /**
+   * Instantiates a new attribute.
    *
-   * @param attributeName
-   * @param attributeValues
+   * @param attributeName the attribute name
+   * @param attributeValues the attribute values
    */
   public Attribute(String attributeName, List<String> attributeValues) {
     this.name = attributeName;
@@ -93,48 +116,71 @@
   }
 
   /**
+   * Instantiates a new attribute.
    *
+   * @param attributeName the attribute name
+   * @param dateFormat the format of the date used
+   */
+  public Attribute(String attributeName, String dateFormat) {
+    this.name = attributeName;        
+    this.valuesStringAttribute = null;
+    this.isDate = true;
+
+    if (dateFormat != null) {
+      m_DateFormat = new SimpleDateFormat(dateFormat);
+    } else {
+      m_DateFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss");
+    }
+  }
+
+  /**
+   * Instantiates a new attribute.
    */
   public Attribute() {
     this("");
   }
 
   /**
+   * Checks if is nominal.
    *
-   * @return
+   * @return true, if is nominal
    */
   public boolean isNominal() {
     return this.isNominal;
   }
 
   /**
+   * Name.
    *
-   * @return
+   * @return the string
    */
   public String name() {
     return this.name;
   }
 
   /**
+   * Value.
    *
-   * @param value
-   * @return
+   * @param value the value
+   * @return the string
    */
   public String value(int value) {
     return attributeValues.get(value);
   }
 
   /**
+   * Checks if is numeric.
    *
-   * @return
+   * @return true, if is numeric
    */
   public boolean isNumeric() {
     return isNumeric;
   }
 
   /**
+   * Num values.
    *
-   * @return
+   * @return the int
    */
   public int numValues() {
     if (isNumeric()) {
@@ -145,28 +191,43 @@
   }
 
   /**
+   * Index.
    *
-   * @return
+   * @return the int
    */
-  public int index() { // RuleClassifier
-    return this.index;
-  }
+  //    public int index() { //RuleClassifier        
+  //        return this.index;
+  //    }
 
+  /**
+   * Format date.
+   *
+   * @param value the value
+   * @return the string
+   */
   String formatDate(double value) {
-    SimpleDateFormat sdf = new SimpleDateFormat();
-    return sdf.format(new Date((long) value));
+    return this.m_DateFormat.format(new Date((long) value));
   }
 
+  /**
+   * Checks if is date.
+   *
+   * @return true, if is date
+   */
   boolean isDate() {
     return isDate;
   }
 
+  /**
+   * The values string attribute.
+   */
   private Map<String, Integer> valuesStringAttribute;
 
   /**
+   * Index of value.
    *
-   * @param value
-   * @return
+   * @param value the value
+   * @return the int
    */
   public final int indexOfValue(String value) {
 
@@ -189,13 +250,20 @@
     }
   }
 
-  @Override
-  public String toString() {
+  /**
+   * Returns a description of this attribute in ARFF format. Quotes
+   * strings if they contain whitespace characters, or if they
+   * are a question mark.
+   *
+   * @return a description of this attribute as a string
+   */
+  public final String toString() {
+
     StringBuffer text = new StringBuffer();
 
-    text.append(ARFF_ATTRIBUTE).append(" ").append(Utils.quote(this.name)).append(" ");
+    text.append(ARFF_ATTRIBUTE).append(" ").append(Utils.quote(this.name())).append(" ");
 
-    if (isNominal) {
+    if (this.isNominal){
       text.append('{');
       Enumeration enu =  enumerateValues();
       while (enu.hasMoreElements()) {
@@ -204,10 +272,12 @@
           text.append(',');
       }
       text.append('}');
-    } else if (isNumeric) {
+    } else if (this.isNumeric){
       text.append(ARFF_ATTRIBUTE_NUMERIC);
-    } else if (isDate) {
-      text.append(ARFF_ATTRIBUTE_DATE);
+    } else if (this.isDate){
+      text.append(ARFF_ATTRIBUTE_DATE).append(" ").append(Utils.quote(m_DateFormat.toPattern()));
+    } else{
+      text.append("UNKNOW");
     }
 
     return text.toString();
diff --git a/samoa-instances/src/main/java/org/apache/samoa/instances/AttributesInformation.java b/samoa-instances/src/main/java/org/apache/samoa/instances/AttributesInformation.java
new file mode 100644
index 0000000..58ece8e
--- /dev/null
+++ b/samoa-instances/src/main/java/org/apache/samoa/instances/AttributesInformation.java
@@ -0,0 +1,152 @@
+package org.apache.samoa.instances;
+
+/*
+ * #%L
+ * SAMOA
+ * %%
+ * Copyright (C) 2014 - 2015 Apache Software Foundation
+ * %%
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * #L%
+ */
+
+import java.io.Serializable;
+import java.util.ArrayList;
+import java.util.List;
+
+public class AttributesInformation implements Serializable {
+
+  /**
+   * The attribute information.
+   */
+  protected List<Attribute> attributes;
+  protected List<Integer> indexValues;
+  /**
+   * The number of attributes.
+   */
+  protected int numberAttributes;
+
+  /**
+   * The attribute used for default for numerical values
+   */
+  protected Attribute defaultNumericAttribute;
+
+  public AttributesInformation(AttributesInformation chunk) {
+    this.attributes = chunk.attributes;
+    this.indexValues = chunk.indexValues;
+    this.numberAttributes = chunk.numberAttributes;
+  }
+
+  public AttributesInformation(List<Attribute> v, List<Integer> i, int numberAttributes) {
+    this.attributes = v;
+    this.indexValues = i;
+    this.numberAttributes = numberAttributes;
+  }
+
+  public AttributesInformation(List<Attribute> v, int numberAttributes) {
+    this.attributes = v;
+    this.indexValues = new ArrayList<Integer>(numberAttributes);
+    for (int i = 0; i < numberAttributes; i++) {
+      this.indexValues.add(i);
+    }
+    this.numberAttributes = numberAttributes;
+  }
+
+  public AttributesInformation() {
+    this.attributes = null;
+    this.indexValues = null;
+    this.numberAttributes = 0;
+    this.defaultNumericAttribute = null;
+  }
+
+  /**
+   * Attribute.
+   *
+   * @param indexAttribute the index Attribute
+   * @return the attribute
+   */
+  public Attribute attribute(int indexAttribute) {
+    if (this.attributes == null) {
+      //All attributes are numeric
+      return defaultNumericAttribute();
+    }
+    int location = locateIndex(indexAttribute);
+    if (location == -1) {
+      //if there is not attribute information, it is numeric
+      return defaultNumericAttribute();
+    }
+    return attributes.get(location);
+  }
+
+  public void add(Attribute attribute, int value) {
+    this.attributes.add(attribute);
+    this.indexValues.add(value);
+  }
+
+  /**
+   * Sets the attribute information.
+   *
+   * @param v the new attribute information
+   */
+  public void setAttributes(List<Attribute> v) {
+    this.attributes = v;
+    this.numberAttributes=v.size();
+  }
+
+  /**
+   * Locates the greatest index that is not greater than the given index.
+   *
+   * @return the internal index of the attribute index. Returns -1 if no index
+   * with this property could be found
+   */
+  public int locateIndex(int index) {
+
+    int min = 0;
+    int max = this.indexValues.size() - 1;
+
+    if (max == -1) {
+      return -1;
+    }
+
+    // Binary search
+    while ((this.indexValues.get(min) <= index) && (this.indexValues.get(max) >= index)) {
+      int current = (max + min) / 2;
+      if (this.indexValues.get(current) > index) {
+        max = current - 1;
+      } else if (this.indexValues.get(current) < index) {
+        min = current + 1;
+      } else {
+        return current;
+      }
+    }
+    if (this.indexValues.get(max) < index) {
+      return max;
+    } else {
+      return min - 1;
+    }
+  }
+
+  private Attribute defaultNumericAttribute() {
+    if (this.defaultNumericAttribute == null) {
+      this.defaultNumericAttribute = new Attribute("default");
+    }
+    return this.defaultNumericAttribute;
+  }
+
+  public void setAttributes(List<Attribute> v, List<Integer> indexValues) {
+    this.attributes = v;
+    this.numberAttributes=v.size();	
+    this.indexValues=indexValues;
+  }
+
+}
diff --git a/samoa-instances/src/main/java/org/apache/samoa/instances/AvroBinaryLoader.java b/samoa-instances/src/main/java/org/apache/samoa/instances/AvroBinaryLoader.java
index 5c57aa1..84b7eec 100644
--- a/samoa-instances/src/main/java/org/apache/samoa/instances/AvroBinaryLoader.java
+++ b/samoa-instances/src/main/java/org/apache/samoa/instances/AvroBinaryLoader.java
@@ -29,9 +29,6 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-/**
- * Load Data from Binary Avro Stream and parse to corresponding Dense & Parse Instances
- */
 public class AvroBinaryLoader extends AvroLoader {
 
   private static final long serialVersionUID = 1L;
diff --git a/samoa-instances/src/main/java/org/apache/samoa/instances/AvroJsonLoader.java b/samoa-instances/src/main/java/org/apache/samoa/instances/AvroJsonLoader.java
index b765405..622347a 100644
--- a/samoa-instances/src/main/java/org/apache/samoa/instances/AvroJsonLoader.java
+++ b/samoa-instances/src/main/java/org/apache/samoa/instances/AvroJsonLoader.java
@@ -34,9 +34,6 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-/**
- * Load Data from JSON Avro Stream and parse to corresponding Dense & Parse Instances
- */
 public class AvroJsonLoader extends AvroLoader {
 
   private static final long serialVersionUID = 1L;
diff --git a/samoa-instances/src/main/java/org/apache/samoa/instances/AvroLoader.java b/samoa-instances/src/main/java/org/apache/samoa/instances/AvroLoader.java
index 2b36744..d3e7f27 100644
--- a/samoa-instances/src/main/java/org/apache/samoa/instances/AvroLoader.java
+++ b/samoa-instances/src/main/java/org/apache/samoa/instances/AvroLoader.java
@@ -31,11 +31,6 @@
 import org.apache.avro.generic.GenericRecord;
 import org.apache.avro.io.DatumReader;
 
-/**
- * Load Data from Avro Stream and parse to corresponding Dense & Parse Instances Abstract Class: Subclass this class for
- * different types of Avro Encodings
- *
- */
 public abstract class AvroLoader implements Loader {
 
   private static final long serialVersionUID = 1L;
@@ -133,11 +128,7 @@
    */
 
   private void setDenseValue(Instance instance, int numAttribute, double valueAttribute) {
-
-    if (this.instanceInformation.classIndex() == numAttribute)
-      instance.setClassValue(valueAttribute);
-    else
-      instance.setValue(numAttribute, valueAttribute);
+    instance.setValue(numAttribute, valueAttribute);
   }
 
   /**
@@ -267,16 +258,16 @@
 
   private boolean isNumeric(Field field) {
     if (field.schema().getType() == Schema.Type.DOUBLE
-            || field.schema().getType() == Schema.Type.FLOAT
-            || field.schema().getType() == Schema.Type.LONG
-            || field.schema().getType() == Schema.Type.INT)
+        || field.schema().getType() == Schema.Type.FLOAT
+        || field.schema().getType() == Schema.Type.LONG
+        || field.schema().getType() == Schema.Type.INT)
       return true;
     if (field.schema().getType() == Schema.Type.UNION) {
       for (Schema schema: field.schema().getTypes()) {
         if (schema.getType() == Schema.Type.DOUBLE
-                || schema.getType() == Schema.Type.FLOAT
-                || schema.getType() == Schema.Type.LONG
-                || schema.getType() == Schema.Type.INT)
+            || schema.getType() == Schema.Type.FLOAT
+            || schema.getType() == Schema.Type.LONG
+            || schema.getType() == Schema.Type.INT)
           return true;
       }
     }
diff --git a/samoa-instances/src/main/java/org/apache/samoa/instances/DenseInstance.java b/samoa-instances/src/main/java/org/apache/samoa/instances/DenseInstance.java
index 80feb11..d8a789b 100644
--- a/samoa-instances/src/main/java/org/apache/samoa/instances/DenseInstance.java
+++ b/samoa-instances/src/main/java/org/apache/samoa/instances/DenseInstance.java
@@ -1,7 +1,3 @@
-/*
- * To change this template, choose Tools | Templates
- * and open the template in the editor.
- */
 package org.apache.samoa.instances;
 
 /*
@@ -24,65 +20,42 @@
  * #L%
  */
 
-import java.text.SimpleDateFormat;
+public class DenseInstance extends InstanceImpl {
 
-/**
- * @author abifet
- */
-public class DenseInstance extends SingleLabelInstance {
-
-  private static final long serialVersionUID = 280360594027716737L;
-
-  public DenseInstance() {
-    // necessary for kryo serializer
-  }
-
+  /**
+   * Instantiates a new dense instance.
+   *
+   * @param weight the weight
+   * @param res the res
+   */
   public DenseInstance(double weight, double[] res) {
     super(weight, res);
   }
 
-  public DenseInstance(SingleLabelInstance inst) {
+  /**
+   * Instantiates a new dense instance.
+   *
+   * @param inst the inst
+   */
+  public DenseInstance(InstanceImpl inst) {
     super(inst);
   }
 
+  /**
+   * Instantiates a new dense instance.
+   *
+   * @param inst the inst
+   */
   public DenseInstance(Instance inst) {
-    super((SingleLabelInstance) inst);
+    super((InstanceImpl) inst);
   }
 
+  /**
+   * Instantiates a new dense instance.
+   *
+   * @param numberAttributes the number attributes
+   */
   public DenseInstance(double numberAttributes) {
     super((int) numberAttributes);
-    // super(1, new double[(int) numberAttributes-1]);
-    // Add missing values
-    // for (int i = 0; i < numberAttributes-1; i++) {
-    // //this.setValue(i, Double.NaN);
-    // }
-
-  }
-
-  @Override
-  public String toString() {
-    StringBuffer text = new StringBuffer();
-
-    //append all attributes except the class attribute.
-    for (int attIndex = 0; attIndex < this.numAttributes()-1; attIndex++) {
-      if (!this.isMissing(attIndex)) {
-        if (this.attribute(attIndex).isNominal()) {
-          int valueIndex = (int) this.value(attIndex);
-          String stringValue = this.attribute(attIndex).value(valueIndex);
-          text.append(stringValue).append(",");
-        } else if (this.attribute(attIndex).isNumeric()) {
-          text.append(this.value(attIndex)).append(",");
-        } else if (this.attribute(attIndex).isDate()) {
-          SimpleDateFormat dateFormatter = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss");
-          text.append(dateFormatter.format(this.value(attIndex))).append(",");
-        }
-      } else {
-        text.append("?,");
-      }
-    }
-    //append the class value at the end of the instance.
-    text.append(this.classAttribute().value((int)classValue()));
-
-    return text.toString();
   }
 }
diff --git a/samoa-instances/src/main/java/org/apache/samoa/instances/DenseInstanceData.java b/samoa-instances/src/main/java/org/apache/samoa/instances/DenseInstanceData.java
index ecb2f88..6781e91 100644
--- a/samoa-instances/src/main/java/org/apache/samoa/instances/DenseInstanceData.java
+++ b/samoa-instances/src/main/java/org/apache/samoa/instances/DenseInstanceData.java
@@ -1,7 +1,3 @@
-/*
- * To change this template, choose Tools | Templates
- * and open the template in the editor.
- */
 package org.apache.samoa.instances;
 
 /*
@@ -24,74 +20,151 @@
  * #L%
  */
 
-/**
- * 
- * @author abifet
- */
-public class DenseInstanceData implements InstanceData {
+public class DenseInstanceData implements InstanceData{
 
+  /**
+   * Instantiates a new dense instance data.
+   *
+   * @param array the array
+   */
   public DenseInstanceData(double[] array) {
     this.attributeValues = array;
   }
 
+  /**
+   * Instantiates a new dense instance data.
+   *
+   * @param length the length
+   */
   public DenseInstanceData(int length) {
     this.attributeValues = new double[length];
   }
 
+  /**
+   * Instantiates a new dense instance data.
+   */
   public DenseInstanceData() {
     this(0);
   }
 
+  /** The attribute values. */
   protected double[] attributeValues;
 
+  /**
+   * Num attributes.
+   *
+   * @return the int
+   */
   @Override
   public int numAttributes() {
     return this.attributeValues.length;
   }
 
+  /**
+   * Value.
+   *
+   * @param indexAttribute the index attribute
+   * @return the double
+   */
   @Override
   public double value(int indexAttribute) {
-    return this.attributeValues[indexAttribute];
+	if (this.attributeValues.length <= indexAttribute)
+      return this.attributeValues[this.attributeValues.length-1];
+    
+	return this.attributeValues[indexAttribute];
   }
 
+  /**
+   * Checks if is missing.
+   *
+   * @param indexAttribute the index attribute
+   * @return true, if is missing
+   */
   @Override
   public boolean isMissing(int indexAttribute) {
     return Double.isNaN(this.value(indexAttribute));
   }
 
+  /**
+   * Num values.
+   *
+   * @return the int
+   */
   @Override
   public int numValues() {
     return numAttributes();
   }
 
+  /**
+   * Index.
+   *
+   * @param indexAttribute the index attribute
+   * @return the int
+   */
   @Override
   public int index(int indexAttribute) {
     return indexAttribute;
   }
 
+  /**
+   * Value sparse.
+   *
+   * @param indexAttribute the index attribute
+   * @return the double
+   */
   @Override
   public double valueSparse(int indexAttribute) {
     return value(indexAttribute);
   }
 
+  /**
+   * Checks if is missing sparse.
+   *
+   * @param indexAttribute the index attribute
+   * @return true, if is missing sparse
+   */
   @Override
   public boolean isMissingSparse(int indexAttribute) {
     return isMissing(indexAttribute);
   }
 
-  /*
-   * @Override public double value(Attribute attribute) { return
-   * value(attribute.index()); }
+  /**
+   * To double array.
+   *
+   * @return the double[]
    */
-
   @Override
   public double[] toDoubleArray() {
-    return attributeValues.clone();
+    return attributeValues;
   }
 
+  /**
+   * Sets the value.
+   *
+   * @param attributeIndex the attribute index
+   * @param d the d
+   */
   @Override
   public void setValue(int attributeIndex, double d) {
     this.attributeValues[attributeIndex] = d;
   }
 
+  @Override
+  public void deleteAttributeAt(int index) {
+
+    double[] newValues = new double[attributeValues.length - 1];
+
+    System.arraycopy(attributeValues, 0, newValues, 0, index);
+    if (index < attributeValues.length - 1) {
+      System.arraycopy(attributeValues, index + 1, newValues, index,
+          attributeValues.length - (index + 1));
+    }
+    attributeValues = newValues;
+  }
+
+  @Override
+  public InstanceData copy() {
+    return new DenseInstanceData(this.attributeValues);
+  }
+
 }
diff --git a/samoa-instances/src/main/java/org/apache/samoa/instances/Instance.java b/samoa-instances/src/main/java/org/apache/samoa/instances/Instance.java
index ee99914..da4dcdd 100644
--- a/samoa-instances/src/main/java/org/apache/samoa/instances/Instance.java
+++ b/samoa-instances/src/main/java/org/apache/samoa/instances/Instance.java
@@ -1,7 +1,3 @@
-/*
- * To change this template, choose Tools | Templates
- * and open the template in the editor.
- */
 package org.apache.samoa.instances;
 
 /*
@@ -26,68 +22,310 @@
 
 import java.io.Serializable;
 
-/**
- * 
- * @author abifet
- */
-
 public interface Instance extends Serializable {
 
-  double weight();
+  /**
+   * Gets the weight of the instance.
+   *
+   * @return the weight
+   */
+  public double weight();
 
-  void setWeight(double weight);
+  /**
+   * Sets the weight.
+   *
+   * @param weight the new weight
+   */
+  public void setWeight(double weight);
 
-  // Attributes
-  Attribute attribute(int instAttIndex);
+  /**
+   * Attribute.
+   *
+   * @param instAttIndex the inst att index
+   * @return the attribute
+   */
+  public Attribute attribute(int instAttIndex);
 
-  void deleteAttributeAt(int i);
+  /**
+   * Delete attribute at.
+   *
+   * @param i the index
+   */
+  public void deleteAttributeAt(int i);
 
-  void insertAttributeAt(int i);
+  /**
+   * Insert attribute at.
+   *
+   * @param i the index
+   */
+  public void insertAttributeAt(int i);
 
-  int numAttributes();
+  /**
+   * Gets the number of attributes.
+   *
+   * @return the number of attributes
+   */
+  public int numAttributes();
 
+  /**
+   * Adds the sparse values.
+   *
+   * @param indexValues the index values
+   * @param attributeValues the attribute values
+   * @param numberAttributes the number attributes
+   */
   public void addSparseValues(int[] indexValues, double[] attributeValues, int numberAttributes);
 
-  // Values
-  int numValues();
+  /**
+   * Gets the number of values, mainly for sparse instances.
+   *
+   * @return the number of values
+   */
+  public int numValues();
 
-  String stringValue(int i);
+  /**
+   * Gets the value of a discrete attribute as a string.
+   *
+   * @param i the i
+   * @return the string
+   */
+  public String stringValue(int i);
 
-  double value(int instAttIndex);
+  /**
+   * Gets the value of an attribute.
+   *
+   * @param instAttIndex the inst att index
+   * @return the double
+   */
+  public double value(int instAttIndex);
 
-  double value(Attribute attribute);
+  /**
+   * Sets an attribute as missing
+   *
+   * @param instAttIndex, the attribute's index     
+   */
+  public void setMissing(int instAttIndex);        
 
-  void setValue(int m_numAttributes, double d);
+  /**
+   * Sets the value of an attribute.
+   *
+   * @param instAttIndex the index
+   * @param value the value
+   */
+  public void setValue(int instAttIndex, double value);
 
-  boolean isMissing(int instAttIndex);
+  /**
+   * Checks if an attribute is missing.
+   *
+   * @param instAttIndex the inst att index
+   * @return true, if is missing
+   */
+  public boolean isMissing(int instAttIndex);
 
-  int index(int i);
+  /**
+   * Gets the index of the attribute given the index of the array in a sparse
+   * representation.
+   *
+   * @param arrayIndex the index of the array
+   * @return the index
+   */
+  public int index(int arrayIndex);
 
-  double valueSparse(int i);
+  /**
+   * Gets the value of an attribute in a sparse representation of the
+   * instance.
+   *
+   * @param i the i
+   * @return the value
+   */
+  public double valueSparse(int i);
 
-  boolean isMissingSparse(int p1);
+  /**
+   * Checks if the attribute is missing sparse.
+   *
+   * @param p1 the p1
+   * @return true, if is missing sparse
+   */
+  public boolean isMissingSparse(int p1);
 
-  double[] toDoubleArray();
+  /**
+   * To double array.
+   *
+   * @return the double[]
+   */
+  public double[] toDoubleArray();
 
-  // Class
-  Attribute classAttribute();
+  /**
+   * Class attribute.
+   *
+   * @return the attribute
+   */
+  public Attribute classAttribute();
 
-  int classIndex();
+  /**
+   * Class index.
+   *
+   * @return the int
+   */
+  public int classIndex();
 
-  boolean classIsMissing();
+  /**
+   * Class is missing.
+   *
+   * @return true, if successful
+   */
+  public boolean classIsMissing();
 
-  double classValue();
+  /**
+   * Class value.
+   *
+   * @return the double
+   */
+  public double classValue();
 
-  int numClasses();
+  /**
+   * Num classes.
+   *
+   * @return the int
+   */
+  public int numClasses();
 
-  void setClassValue(double d);
+  /**
+   * Sets the class value.
+   *
+   * @param d the new class value
+   */
+  public void setClassValue(double d);
 
-  Instance copy();
+  /**
+   * Copy.
+   *
+   * @return the instance
+   */
+  public Instance copy();
 
-  // Dataset
-  void setDataset(Instances dataset);
+  /**
+   * Sets the dataset.
+   *
+   * @param dataset the new dataset
+   */
+  public void setDataset(Instances dataset);
 
-  Instances dataset();
+  /**
+   * Dataset.
+   *
+   * @return the instances
+   */
+  public Instances dataset();
 
-  String toString();
+  /**
+   * Gets the number of input attributes.
+   *
+   * @return the number of input attributes
+   */
+  public int numInputAttributes();
+
+  /**
+   * Gets the number of output attributes.
+   *
+   * @return the number of output attributes
+   */
+  public int numOutputAttributes();
+
+  /**
+   * Gets the number of output attributes.
+   *
+   * @return the number of output attributes
+   */
+  public int numberOutputTargets();
+
+  /**
+   * Gets the value of an output attribute.
+   *
+   * @param attributeIndex the index
+   * @return the value
+   */
+  public double classValue(int attributeIndex);
+
+  /**
+   * Sets the value of an output attribute.
+   *
+   * @param indexClass the output attribute index
+   * @param valueAttribute the value of the attribute
+   */
+  public void setClassValue(int indexClass, double valueAttribute);
+
+  /**
+   * Gets an output attribute given its index.
+   *
+   * @param attributeIndex the index
+   * @return the attribute
+   */
+  public Attribute outputAttribute(int attributeIndex);
+
+  /**
+   * Gets an input attribute given its index.
+   *
+   * @param attributeIndex the index
+   * @return the attribute
+   */
+  public Attribute inputAttribute(int attributeIndex);
+
+  /**
+   * Gets the value of an input attribute.
+   *
+   * @param attributeIndex the index
+   * @return the value
+   */
+  public double valueInputAttribute(int attributeIndex);
+
+  /**
+   * Gets the value of an output attribute.
+   *
+   * @param attributeIndex the index
+   * @return the value
+   */
+  public double valueOutputAttribute(int attributeIndex);
+
+  /**
+   * Index of an Attribute.
+   *
+   * @param attribute, the attribute to be found.
+   * @return the index of an attribute
+   */
+  public int indexOfAttribute(Attribute attribute);
+
+  /**
+   * Gets the value of an attribute, given the attribute.
+   *
+   * @param attribute the attribute
+   * @return the double
+   */
+  public double value(Attribute attribute);
+
+  /**
+   * Sets an attribute as missing
+   *
+   * @param attribute, the Attribute
+   */
+  public void setMissing(Attribute attribute);
+
+  /**
+   * Sets the value of an attribute.
+   *
+   * @param attribute, the Attribute
+   * @param value the value
+   */
+  public void setValue(Attribute attribute, double value);
+
+  /**
+   * Checks if an attribute is missing.
+   *
+   * @param attribute, the Attribute
+   * @return true, if is missing
+   */
+  public boolean isMissing(Attribute attribute);
+
+
+
 }
diff --git a/samoa-instances/src/main/java/org/apache/samoa/instances/InstanceData.java b/samoa-instances/src/main/java/org/apache/samoa/instances/InstanceData.java
index eca4145..b735ea5 100644
--- a/samoa-instances/src/main/java/org/apache/samoa/instances/InstanceData.java
+++ b/samoa-instances/src/main/java/org/apache/samoa/instances/InstanceData.java
@@ -1,7 +1,3 @@
-/*
- * To change this template, choose Tools | Templates
- * and open the template in the editor.
- */
 package org.apache.samoa.instances;
 
 /*
@@ -26,30 +22,90 @@
 
 import java.io.Serializable;
 
-/**
- * 
- * @author abifet
- */
 public interface InstanceData extends Serializable {
 
+  /**
+   * Num attributes.
+   *
+   * @return the int
+   */
   public int numAttributes();
 
+  /**
+   * Value.
+   *
+   * @param instAttIndex the inst att index
+   * @return the double
+   */
   public double value(int instAttIndex);
 
+  /**
+   * Checks if is missing.
+   *
+   * @param instAttIndex the inst att index
+   * @return true, if is missing
+   */
   public boolean isMissing(int instAttIndex);
 
+  /**
+   * Num values.
+   *
+   * @return the int
+   */
   public int numValues();
 
+  /**
+   * Index.
+   *
+   * @param i the i
+   * @return the int
+   */
   public int index(int i);
 
+  /**
+   * Value sparse.
+   *
+   * @param i the i
+   * @return the double
+   */
   public double valueSparse(int i);
 
+  /**
+   * Checks if is missing sparse.
+   *
+   * @param p1 the p1
+   * @return true, if is missing sparse
+   */
   public boolean isMissingSparse(int p1);
 
-  // public double value(Attribute attribute);
-
+  /**
+   * To double array.
+   *
+   * @return the double[]
+   */
   public double[] toDoubleArray();
 
+  /**
+   * Sets the value.
+   *
+   * @param m_numAttributes the m_num attributes
+   * @param d the d
+   */
   public void setValue(int m_numAttributes, double d);
 
+
+  /**
+   * Deletes an attribute.
+   *
+   * @param index the indes
+   */
+  public void deleteAttributeAt(int index);
+
+  /**
+   * Produces a shallow copy of this instance data. 
+   * 
+   * @return the shallow copy
+   */
+  public InstanceData copy();
+
 }
diff --git a/samoa-instances/src/main/java/org/apache/samoa/instances/InstanceImpl.java b/samoa-instances/src/main/java/org/apache/samoa/instances/InstanceImpl.java
new file mode 100644
index 0000000..ff77dc2
--- /dev/null
+++ b/samoa-instances/src/main/java/org/apache/samoa/instances/InstanceImpl.java
@@ -0,0 +1,483 @@
+package org.apache.samoa.instances;
+
+/*
+ * #%L
+ * SAMOA
+ * %%
+ * Copyright (C) 2014 - 2015 Apache Software Foundation
+ * %%
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * #L%
+ */
+
+import java.text.SimpleDateFormat;
+
+public class InstanceImpl implements MultiLabelInstance {
+
+  /**
+   * The weight.
+   */
+  protected double weight;
+
+  /**
+   * The instance data.
+   */
+  protected InstanceData instanceData;
+
+  /**
+   * The instance information.
+   */
+  protected InstancesHeader instanceHeader;
+
+  /**
+   * Instantiates a new instance.
+   *
+   * @param inst the inst
+   */
+  public InstanceImpl(InstanceImpl inst) {
+    this.weight = inst.weight;
+    this.instanceData = inst.instanceData;
+    this.instanceHeader = inst.instanceHeader;
+  }
+
+  //Dense
+  /**
+   * Instantiates a new instance.
+   *
+   * @param weight the weight
+   * @param res the res
+   */
+  public InstanceImpl(double weight, double[] res) {
+    this.weight = weight;
+    this.instanceData = new DenseInstanceData(res);
+  }
+
+  //Sparse
+  /**
+   * Instantiates a new instance.
+   *
+   * @param weight the weight
+   * @param attributeValues the attribute values
+   * @param indexValues the index values
+   * @param numberAttributes the number attributes
+   */
+  public InstanceImpl(double weight, double[] attributeValues, int[] indexValues, int numberAttributes) {
+    this.weight = weight;
+    this.instanceData = new SparseInstanceData(attributeValues, indexValues, numberAttributes);
+  }
+
+  /**
+   * Instantiates a new instance.
+   *
+   * @param weight the weight
+   * @param instanceData the instance data
+   */
+  public InstanceImpl(double weight, InstanceData instanceData) {
+    this.weight = weight;
+    this.instanceData = instanceData;
+  }
+
+  /**
+   * Instantiates a new instance.
+   *
+   * @param numAttributes the num attributes
+   */
+  public InstanceImpl(int numAttributes) {
+    this.instanceData = new DenseInstanceData(new double[numAttributes]); //JD
+    this.weight = 1;
+  }
+
+  /**
+   * Weight.
+   *
+   * @return the double
+   */
+  @Override
+  public double weight() {
+    return weight;
+  }
+
+  /**
+   * Sets the weight.
+   *
+   * @param weight the new weight
+   */
+  @Override
+  public void setWeight(double weight) {
+    this.weight = weight;
+  }
+
+  /**
+   * Attribute.
+   *
+   * @param instAttIndex the inst att index
+   * @return the attribute
+   */
+  @Override
+  public Attribute attribute(int instAttIndex) {
+    return this.instanceHeader.attribute(instAttIndex);
+  }
+
+  public int indexOfAttribute(Attribute attribute){
+    return this.instanceHeader.indexOf(attribute);
+  }
+
+  /**
+   * Delete attribute at.
+   *
+   * @param i the i
+   */
+  @Override
+  public void deleteAttributeAt(int i) {
+    this.instanceData.deleteAttributeAt(i);
+  }
+
+  /**
+   * Insert attribute at.
+   *
+   * @param i the i
+   */
+  @Override
+  public void insertAttributeAt(int i) {
+    throw new UnsupportedOperationException("Not yet implemented");
+  }
+
+  /**
+   * Num attributes.
+   *
+   * @return the int
+   */
+  @Override
+  public int numAttributes() {
+    return this.instanceData.numAttributes();
+  }
+
+  /**
+   * Value.
+   *
+   * @param instAttIndex the inst att index
+   * @return the double
+   */
+  @Override
+  public double value(int instAttIndex) {
+    return this.instanceData.value(instAttIndex);
+  }
+
+  /**
+   * Checks if is missing.
+   *
+   * @param instAttIndex the inst att index
+   * @return true, if is missing
+   */
+  @Override
+  public boolean isMissing(int instAttIndex) {
+    return this.instanceData.isMissing(instAttIndex);
+  }
+
+  /**
+   * Num values.
+   *
+   * @return the int
+   */
+  @Override
+  public int numValues() {
+    return this.instanceData.numValues();
+  }
+
+  /**
+   * Index.
+   *
+   * @param i the i
+   * @return the int
+   */
+  @Override
+  public int index(int i) {
+    return this.instanceData.index(i);
+  }
+
+  /**
+   * Value sparse.
+   *
+   * @param i the i
+   * @return the double
+   */
+  @Override
+  public double valueSparse(int i) {
+    return this.instanceData.valueSparse(i);
+  }
+
+  /**
+   * Checks if is missing sparse.
+   *
+   * @param p the p
+   * @return true, if is missing sparse
+   */
+  @Override
+  public boolean isMissingSparse(int p) {
+    return this.instanceData.isMissingSparse(p);
+  }
+
+  /**
+   * String value.
+   *
+   * @param i the i
+   * @return the string
+   */
+  @Override
+  public String stringValue(int i) {
+    throw new UnsupportedOperationException("Not yet implemented");
+  }
+
+  /**
+   * To double array.
+   *
+   * @return the double[]
+   */
+  @Override
+  public double[] toDoubleArray() {
+    return this.instanceData.toDoubleArray();
+  }
+
+  /**
+   * Sets the value.
+   *
+   * @param numAttribute the num attribute
+   * @param d the d
+   */
+  @Override
+  public void setValue(int numAttribute, double d) {
+    this.instanceData.setValue(numAttribute, d);
+  }
+
+  /**
+   * Class value.
+   *
+   * @return the double
+   */
+  @Override
+  public double classValue() {
+    return this.instanceData.value(classIndex());
+  }
+
+  /**
+   * Class index.
+   *
+   * @return the int
+   */
+  @Override
+  public int classIndex() {
+    int classIndex = instanceHeader.classIndex();
+    //return classIndex != Integer.MAX_VALUE ? classIndex : 0;
+    // return  ? classIndex : 0;
+    if(classIndex == Integer.MAX_VALUE)
+      if(this.instanceHeader.instanceInformation.range!=null)
+        classIndex=instanceHeader.instanceInformation.range.getStart();
+      else
+        classIndex=0;
+    return classIndex;
+  }
+
+  /**
+   * Num classes.
+   *
+   * @return the int
+   */
+  @Override
+  public int numClasses() {
+    return this.instanceHeader.numClasses();
+  }
+
+  /**
+   * Class is missing.
+   *
+   * @return true, if successful
+   */
+  @Override
+  public boolean classIsMissing() {
+    return this.instanceData.isMissing(classIndex());
+  }
+
+  /**
+   * Class attribute.
+   *
+   * @return the attribute
+   */
+  @Override
+  public Attribute classAttribute() {
+    return this.instanceHeader.attribute(classIndex());
+  }
+
+  /**
+   * Sets the class value.
+   *
+   * @param d the new class value
+   */
+  @Override
+  public void setClassValue(double d) {
+    this.setValue(classIndex(), d);
+  }
+
+  /**
+   * Copy.
+   *
+   * @return the instance
+   */
+  @Override
+  public Instance copy() {
+    InstanceImpl inst = new InstanceImpl(this);
+    return inst;
+  }
+
+  /**
+   * Dataset.
+   *
+   * @return the instances
+   */
+  @Override
+  public Instances dataset() {
+    return this.instanceHeader;
+  }
+
+  /**
+   * Sets the dataset.
+   *
+   * @param dataset the new dataset
+   */
+  @Override
+  public void setDataset(Instances dataset) {
+    this.instanceHeader = new InstancesHeader(dataset);
+  }
+
+  /**
+   * Adds the sparse values.
+   *
+   * @param indexValues the index values
+   * @param attributeValues the attribute values
+   * @param numberAttributes the number attributes
+   */
+  @Override
+  public void addSparseValues(int[] indexValues, double[] attributeValues, int numberAttributes) {
+    this.instanceData = new SparseInstanceData(attributeValues, indexValues, numberAttributes); //???
+  }
+
+  /**
+   * Text representation of a InstanceImpl.
+   */
+  @Override
+  public String toString() {
+    StringBuilder str = new StringBuilder();
+    for (int attIndex = 0; attIndex < this.numAttributes(); attIndex++) {
+      if (!this.isMissing(attIndex)) {
+        if (this.attribute(attIndex).isNominal()) {
+          int valueIndex = (int) this.value(attIndex);
+          String stringValue = this.attribute(attIndex).value(valueIndex);
+          str.append(stringValue).append(",");
+        } else if (this.attribute(attIndex).isNumeric()) {
+          str.append(this.value(attIndex)).append(",");
+        } else if (this.attribute(attIndex).isDate()) {
+          SimpleDateFormat dateFormatter = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss");
+          str.append(dateFormatter.format(this.value(attIndex))).append(",");
+        }
+      } else {
+        str.append("?,");
+      }
+    }
+    return str.toString();
+  }
+
+  @Override
+  public int numInputAttributes() {
+    return this.instanceHeader.numInputAttributes();
+  }
+
+  @Override
+  public int numOutputAttributes() {
+    return numberOutputTargets();
+  }
+
+  @Override
+  public int numberOutputTargets() {
+    return this.instanceHeader.numOutputAttributes();
+  }
+
+  @Override
+  public double classValue(int instAttIndex) {
+    return valueOutputAttribute(instAttIndex);
+  }
+
+  @Override
+  public void setClassValue(int indexClass, double valueAttribute) {
+    InstanceInformation instanceInformation = this.instanceHeader.getInstanceInformation();
+    this.instanceData.setValue(instanceInformation.outputAttributeIndex(indexClass), valueAttribute);
+
+  }
+
+  @Override
+  public Attribute outputAttribute(int outputIndex) {
+    InstanceInformation instanceInformation = this.instanceHeader.getInstanceInformation();
+    return instanceInformation.outputAttribute(outputIndex);
+  }
+
+  @Override
+  public Attribute inputAttribute(int attributeIndex) {
+    InstanceInformation instanceInformation = this.instanceHeader.getInstanceInformation();
+    return instanceInformation.inputAttribute(attributeIndex);
+  }
+
+  @Override
+  public double valueInputAttribute(int attributeIndex) {
+    InstanceInformation instanceInformation = this.instanceHeader.getInstanceInformation();
+    return this.instanceData.value(instanceInformation.inputAttributeIndex(attributeIndex));
+  }
+
+  @Override
+  public double valueOutputAttribute(int attributeIndex) {
+    InstanceInformation instanceInformation = this.instanceHeader.getInstanceInformation();
+    return this.instanceData.value(instanceInformation.outputAttributeIndex(attributeIndex));
+  }
+
+  @Override
+  public void setMissing(int instAttIndex) {
+    this.setValue(instAttIndex, Double.NaN);
+  }
+
+  /**
+   * Value.
+   *
+   * @param attribute the attribute
+   * @return the double
+   */
+  @Override
+  public double value(Attribute attribute) {
+    int index = this.instanceHeader.indexOf(attribute);
+    return value(index);
+  }
+
+  @Override
+  public void setMissing(Attribute attribute) {
+    int index = this.instanceHeader.indexOf(attribute);
+    this.setMissing(index);
+  }
+
+  @Override
+  public boolean isMissing(Attribute attribute) {
+    int index = this.instanceHeader.indexOf(attribute);
+    return this.isMissing(index);
+  }
+
+  @Override
+  public void setValue(Attribute attribute, double value) {
+    int index = this.instanceHeader.indexOf(attribute);
+    this.setValue(index, value);
+  }
+}
diff --git a/samoa-instances/src/main/java/org/apache/samoa/instances/InstanceInformation.java b/samoa-instances/src/main/java/org/apache/samoa/instances/InstanceInformation.java
index 639f065..cfd7f51 100644
--- a/samoa-instances/src/main/java/org/apache/samoa/instances/InstanceInformation.java
+++ b/samoa-instances/src/main/java/org/apache/samoa/instances/InstanceInformation.java
@@ -1,7 +1,3 @@
-/*
- * To change this template, choose Tools | Templates
- * and open the template in the editor.
- */
 package org.apache.samoa.instances;
 
 /*
@@ -27,82 +23,194 @@
 import java.io.Serializable;
 import java.util.List;
 
-/**
- * 
- * @author abifet
- */
 public class InstanceInformation implements Serializable {
 
-  // Should we split Instances as a List of Instances, and InformationInstances
-
-  /** The dataset's name. */
+  /**
+   * The dataset's name.
+   */
   protected String relationName;
 
-  /** The attribute information. */
-  protected List<Attribute> attributes;
+  protected AttributesInformation attributesInformation;
 
-  protected int classIndex;
+  /**
+   * The class index.
+   */
+  protected int classIndex = Integer.MAX_VALUE; //By default is multilabel
 
+  /**
+   * Range for multi-label instances.
+   */
+  protected Range range;
+
+  public Attribute inputAttribute(int w) {
+    return this.attributesInformation.attribute(inputAttributeIndex(w));
+  }
+
+  public Attribute outputAttribute(int w) {
+    return this.attributesInformation.attribute(outputAttributeIndex(w));
+  }
+
+  /**
+   * Instantiates a new instance information.
+   *
+   * @param chunk the chunk
+   */
   public InstanceInformation(InstanceInformation chunk) {
     this.relationName = chunk.relationName;
-    this.attributes = chunk.attributes;
+    this.attributesInformation = chunk.attributesInformation;
     this.classIndex = chunk.classIndex;
   }
 
-  public InstanceInformation(String st, List<Attribute> v) {
+  /**
+   * Instantiates a new instance information.
+   *
+   * @param st the st
+   * @param v the v
+   */
+  public InstanceInformation(String st, List<Attribute> input) {
     this.relationName = st;
-    this.attributes = v;
+    this.attributesInformation = new AttributesInformation(input, input.size());
   }
 
+  /**
+   * Instantiates a new instance information.
+   */
   public InstanceInformation() {
     this.relationName = null;
-    this.attributes = null;
+    this.attributesInformation = null;
   }
 
-  // Information Instances
-
+  //Information Instances
+  /* (non-Javadoc)
+   * @see com.yahoo.labs.samoa.instances.InstanceInformationInterface#setRelationName(java.lang.String)
+   */
   public void setRelationName(String string) {
     this.relationName = string;
   }
 
+  /* (non-Javadoc)
+   * @see com.yahoo.labs.samoa.instances.InstanceInformationInterface#getRelationName()
+   */
   public String getRelationName() {
     return this.relationName;
   }
 
+  /* (non-Javadoc)
+   * @see com.yahoo.labs.samoa.instances.InstanceInformationInterface#classIndex()
+   */
   public int classIndex() {
-    return classIndex;
+    return this.classIndex;
   }
 
+  /* (non-Javadoc)
+   * @see com.yahoo.labs.samoa.instances.InstanceInformationInterface#setClassIndex(int)
+   */
   public void setClassIndex(int classIndex) {
     this.classIndex = classIndex;
   }
 
+  /* (non-Javadoc)
+   * @see com.yahoo.labs.samoa.instances.InstanceInformationInterface#classAttribute()
+   */
   public Attribute classAttribute() {
     return this.attribute(this.classIndex());
   }
 
+  /* (non-Javadoc)
+   * @see com.yahoo.labs.samoa.instances.InstanceInformationInterface#numAttributes()
+   */
   public int numAttributes() {
-    return this.attributes.size();
+    return this.attributesInformation.numberAttributes;
   }
 
+  /* (non-Javadoc)
+   * @see com.yahoo.labs.samoa.instances.InstanceInformationInterface#attribute(int)
+   */
   public Attribute attribute(int w) {
-    return this.attributes.get(w);
+    return this.attributesInformation.attribute(w);
   }
 
+  /* (non-Javadoc)
+   * @see com.yahoo.labs.samoa.instances.InstanceInformationInterface#numClasses()
+   */
   public int numClasses() {
-    return this.attributes.get(this.classIndex()).numValues();
+    return this.attributesInformation.attribute(classIndex()).numValues();
   }
 
+  /* (non-Javadoc)
+   * @see com.yahoo.labs.samoa.instances.InstanceInformationInterface#deleteAttributeAt(java.lang.Integer)
+   */
   public void deleteAttributeAt(Integer integer) {
     throw new UnsupportedOperationException("Not yet implemented");
   }
 
+  /* (non-Javadoc)
+   * @see com.yahoo.labs.samoa.instances.InstanceInformationInterface#insertAttributeAt(com.yahoo.labs.samoa.instances.Attribute, int)
+   */
   public void insertAttributeAt(Attribute attribute, int i) {
     throw new UnsupportedOperationException("Not yet implemented");
   }
 
   public void setAttributes(List<Attribute> v) {
-    this.attributes = v;
+    if(this.attributesInformation==null)
+      this.attributesInformation= new AttributesInformation();
+    this.attributesInformation.setAttributes(v);
+  }
+
+  public int inputAttributeIndex(int index) {
+    int ret = 0;
+    if (classIndex == Integer.MAX_VALUE) {//Multi Label
+      if(index<range.getStart())//JD
+        ret= index;
+      else 
+        ret= index+range.getSelectionLength();
+
+    } else { //Single Label
+      ret = classIndex() > index ? index : index + 1;
+    }
+    return ret;
+  }
+
+  public int outputAttributeIndex(int attributeIndex) {
+    int ret = 0;
+    if (classIndex == Integer.MAX_VALUE) {//Multi Label
+      ret=attributeIndex+range.getStart(); //JD - Range should be a "block"
+    } else { //Single Label
+      ret = classIndex;
+    }
+    return ret;
+  }
+
+  public int numInputAttributes() {
+    int ret = 0;
+    if (classIndex == Integer.MAX_VALUE) {//Multi Label
+      ret=this.numAttributes()-range.getSelectionLength(); //JD
+    } else { //Single Label
+      ret = this.numAttributes() - 1;
+    }
+    return ret;
+  }
+
+  public int numOutputAttributes() {
+    int ret = 0;
+    if (classIndex == Integer.MAX_VALUE) {//Multi Label
+      ret=range.getSelectionLength(); //JD
+    } else { //Single Label
+      ret = 1;
+    }
+    return ret;
+  }
+
+  public void setRangeOutputIndices(Range range) {
+    this.setClassIndex(Integer.MAX_VALUE);
+    this.range = range;
+  }
+
+  public void setAttributes(List<Attribute> v, List<Integer> indexValues) {
+    if(this.attributesInformation==null)
+      this.attributesInformation= new AttributesInformation();
+    this.attributesInformation.setAttributes(v,indexValues);
+
   }
 
 }
diff --git a/samoa-instances/src/main/java/org/apache/samoa/instances/Instances.java b/samoa-instances/src/main/java/org/apache/samoa/instances/Instances.java
index f7fb0d3..04fde39 100644
--- a/samoa-instances/src/main/java/org/apache/samoa/instances/Instances.java
+++ b/samoa-instances/src/main/java/org/apache/samoa/instances/Instances.java
@@ -1,9 +1,7 @@
-/*
- * To change this template, choose Tools | Templates
- * and open the template in the editor.
- */
 package org.apache.samoa.instances;
 
+import java.io.InputStream;
+
 /*
  * #%L
  * SAMOA
@@ -28,56 +26,84 @@
 import java.io.Serializable;
 import java.io.StringReader;
 import java.util.ArrayList;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Random;
-import java.io.InputStream;
 
-/**
- * 
- * @author abifet
- */
 public class Instances implements Serializable {
 
-  public static final String ARFF_RELATION = "@relation";
-  public static final String ARFF_DATA = "@data";
+  /**
+   * The keyword used to denote the start of an arff header
+   */
+  public final static String ARFF_RELATION = "@relation";
 
+  /**
+   * The keyword used to denote the start of the arff data section
+   */
+  public final static String ARFF_DATA = "@data";
+
+  private static final long serialVersionUID = 8110510475535581577L;
+  /**
+   * The instance information.
+   */
   protected InstanceInformation instanceInformation;
   /**
    * The instances.
    */
   protected List<Instance> instances;
 
-  transient protected Loader loader;
-
   protected static enum AVRO_ENCODING_FORMAT {
     JSON, BINARY
   }
 
   protected int classAttribute;
 
-  public Instances(InstancesHeader modelContext) {
-    throw new UnsupportedOperationException("Not yet implemented");
-  }
+  /**
+   * A Hash that stores the indices of features.
+   */
+  protected HashMap<String, Integer> hsAttributesIndices;
 
+  transient protected Loader loader;
+
+  /**
+   * Instantiates a new instances.
+   *
+   * @param chunk the chunk
+   */
   public Instances(Instances chunk) {
-    this.instanceInformation = chunk.instanceInformation();
-    // this.relationName = chunk.relationName;
-    // this.attributes = chunk.attributes;
-    this.instances = chunk.instances;
+    this(chunk, chunk.numInstances());
+    chunk.copyInstances(0, this, chunk.numInstances());
   }
 
+  /**
+   * Instantiates a new instances.
+   */
   public Instances() {
-    // this.instanceInformation = chunk.instanceInformation();
-    // this.relationName = chunk.relationName;
-    // this.attributes = chunk.attributes;
-    // this.instances = chunk.instances;
   }
 
+  /**
+   * Instantiates a new instances.
+   *
+   * @param reader the reader
+   * @param size the size
+   * @param classAttribute the class attribute
+   */
   public Instances(Reader reader, int size, int classAttribute) {
-    this.classAttribute = classAttribute;
-    loader = new ArffLoader(reader, 0, classAttribute);
+    this.loader = new ArffLoader(reader, 0, classAttribute);
     this.instanceInformation = loader.getStructure();
-    this.instances = new ArrayList<>();
+    this.instances = new ArrayList<Instance>();
+  }
+
+  /**
+   * Instantiates a new instances.
+   *
+   * @param reader the reader
+   * @param range
+   */
+  public Instances(Reader reader, Range range) {
+    this.loader = new ArffLoader(reader, 0, classAttribute);//new MultiTargetArffLoader(reader, range);
+    this.instanceInformation = loader.getStructure();
+    this.instances = new ArrayList<Instance>();
   }
 
   public Instances(InputStream inputStream, int classAttribute, String encodingFormat) {
@@ -92,110 +118,337 @@
     this.instances = new ArrayList<>();
   }
 
+  /**
+   * Instantiates a new instances.
+   *
+   * @param chunk the chunk
+   * @param capacity the capacity
+   */
   public Instances(Instances chunk, int capacity) {
-    this(chunk);
+    this.instanceInformation = chunk.instanceInformation();
+    if (capacity < 0) {
+      capacity = 0;
+    }
+    this.instances = new ArrayList<Instance>(capacity);
   }
 
+  /**
+   * Instantiates a new instances.
+   *
+   * @param st the st
+   * @param v the v
+   * @param capacity the capacity
+   */
   public Instances(String st, List<Attribute> v, int capacity) {
-
     this.instanceInformation = new InstanceInformation(st, v);
-    this.instances = new ArrayList<>();
+    this.instances = new ArrayList<Instance>(capacity);
   }
 
-  public Instances(Instances chunk, int i, int j) {
-    throw new UnsupportedOperationException("Not yet implemented");
+  /**
+   * Instantiates a new instances.
+   *
+   * @param chunk the chunk
+   * @param first the first instance
+   * @param toCopy the j
+   */
+  public Instances(Instances chunk, int first, int toCopy) {
+
+    this(chunk, toCopy);
+
+    if ((first < 0) || ((first + toCopy) > chunk.numInstances())) {
+      throw new IllegalArgumentException("Parameters first and/or toCopy out "
+          + "of range");
+    }
+    chunk.copyInstances(first, this, toCopy);
   }
 
-  public Instances(StringReader st, int v) {
-    throw new UnsupportedOperationException("Not yet implemented");
+  /**
+   * Instantiates a new instances.
+   *
+   * @param st the st
+   * @param capacity the capacity
+   */
+  public Instances(StringReader st, int capacity) {
+    this.instances = new ArrayList<Instance>(capacity);
   }
 
-  // Information Instances
+  //Information Instances
+  /**
+   * Sets the relation name.
+   *
+   * @param string the new relation name
+   */
   public void setRelationName(String string) {
     this.instanceInformation.setRelationName(string);
   }
 
+  /**
+   * Gets the relation name.
+   *
+   * @return the relation name
+   */
   public String getRelationName() {
     return this.instanceInformation.getRelationName();
   }
 
+  /**
+   * Class index.
+   *
+   * @return the int
+   */
   public int classIndex() {
     return this.instanceInformation.classIndex();
   }
 
+  /**
+   * Sets the class index.
+   *
+   * @param classIndex the new class index
+   */
   public void setClassIndex(int classIndex) {
     this.instanceInformation.setClassIndex(classIndex);
   }
 
+  /**
+   * Class attribute.
+   *
+   * @return the attribute
+   */
   public Attribute classAttribute() {
     return this.instanceInformation.classAttribute();
   }
 
+  /**
+   * Num attributes.
+   *
+   * @return the int
+   */
   public int numAttributes() {
     return this.instanceInformation.numAttributes();
   }
 
+  /**
+   * Attribute.
+   *
+   * @param w the w
+   * @return the attribute
+   */
   public Attribute attribute(int w) {
     return this.instanceInformation.attribute(w);
   }
 
+  /**
+   * Num classes.
+   *
+   * @return the int
+   */
   public int numClasses() {
     return this.instanceInformation.numClasses();
   }
 
+  /**
+   * Delete attribute at.
+   *
+   * @param integer the integer
+   */
   public void deleteAttributeAt(Integer integer) {
     this.instanceInformation.deleteAttributeAt(integer);
   }
 
+  /**
+   * Insert attribute at.
+   *
+   * @param attribute the attribute
+   * @param i the i
+   */
   public void insertAttributeAt(Attribute attribute, int i) {
+    if (this.instanceInformation == null) {
+      this.instanceInformation = new InstanceInformation();
+    }
     this.instanceInformation.insertAttributeAt(attribute, i);
   }
 
-  // List of Instances
+  //List of Instances
+  /**
+   * Instance.
+   *
+   * @param num the num
+   * @return the instance
+   */
   public Instance instance(int num) {
     return this.instances.get(num);
   }
 
+  /**
+   * Num instances.
+   *
+   * @return the int
+   */
   public int numInstances() {
     return this.instances.size();
   }
 
+  /**
+   * Adds the.
+   *
+   * @param inst the inst
+   */
   public void add(Instance inst) {
-    this.instances.add(inst.copy());
+    this.instances.add(inst);
   }
 
+  /**
+   * Randomize.
+   *
+   * @param random the random
+   */
   public void randomize(Random random) {
     for (int j = numInstances() - 1; j > 0; j--) {
       swap(j, random.nextInt(j + 1));
     }
   }
 
+  /**
+   * Stratify.
+   *
+   * @param numFolds the num folds
+   */
   public void stratify(int numFolds) {
-    throw new UnsupportedOperationException("Not yet implemented");
+
+    if (classAttribute().isNominal()) {
+
+      // sort by class
+      int index = 1;
+      while (index < numInstances()) {
+        Instance instance1 = instance(index - 1);
+        for (int j = index; j < numInstances(); j++) {
+          Instance instance2 = instance(j);
+          if ((instance1.classValue() == instance2.classValue())
+              || (instance1.classIsMissing()
+                  && instance2.classIsMissing())) {
+            swap(index, j);
+            index++;
+          }
+        }
+        index++;
+      }
+      stratStep(numFolds);
+    }
   }
 
-  public Instances trainCV(int numFolds, int n, Random random) {
-    throw new UnsupportedOperationException("Not yet implemented");
+  protected void stratStep(int numFolds) {
+    ArrayList<Instance> newVec = new ArrayList<Instance>(this.instances.size());
+    int start = 0, j;
+
+    // create stratified batch
+    while (newVec.size() < numInstances()) {
+      j = start;
+      while (j < numInstances()) {
+        newVec.add(instance(j));
+        j = j + numFolds;
+      }
+      start++;
+    }
+    this.instances = newVec;
   }
 
-  public Instances testCV(int numFolds, int n) {
-    throw new UnsupportedOperationException("Not yet implemented");
+  /**
+   * Train cv.
+   *
+   * @param numFolds the num folds
+   * @param numFold
+   * @param random the random
+   * @return the instances
+   */
+  public Instances trainCV(int numFolds, int numFold, Random random) {
+    Instances train = trainCV(numFolds, numFold);
+    train.randomize(random);
+    return train;
   }
 
-  /*
-   * public Instances dataset() { throw new
-   * UnsupportedOperationException("Not yet implemented"); }
+  public Instances trainCV(int numFolds, int numFold) {
+    int numInstForFold, first, offset;
+    Instances train;
+
+    numInstForFold = numInstances() / numFolds;
+    if (numFold < numInstances() % numFolds) {
+      numInstForFold++;
+      offset = numFold;
+    } else {
+      offset = numInstances() % numFolds;
+    }
+    train = new Instances(this, numInstances() - numInstForFold);
+    first = numFold * (numInstances() / numFolds) + offset;
+    copyInstances(0, train, first);
+    copyInstances(first + numInstForFold, train,
+        numInstances() - first - numInstForFold);
+    return train;
+  }
+
+  protected void copyInstances(int from, Instances dest, int num) {
+    for (int i = 0; i < num; i++) {
+      dest.add(instance(from + i));
+    }
+  }
+
+  /**
+   * Test cv.
+   *
+   * @param numFolds the num folds
+   * @param numFold the num fold
+   * @return the instances
+   */
+  public Instances testCV(int numFolds, int numFold) {
+
+    int numInstForFold, first, offset;
+    Instances test;
+
+    numInstForFold = numInstances() / numFolds;
+    if (numFold < numInstances() % numFolds) {
+      numInstForFold++;
+      offset = numFold;
+    } else {
+      offset = numInstances() % numFolds;
+    }
+    test = new Instances(this, numInstForFold);
+    first = numFold * (numInstances() / numFolds) + offset;
+    copyInstances(first, test, numInstForFold);
+    return test;
+  }
+
+  /*  public Instances dataset() {
+     throw new UnsupportedOperationException("Not yet implemented");
+     }*/
+  /**
+   * Mean or mode.
+   *
+   * @param j the j
+   * @return the double
    */
   public double meanOrMode(int j) {
-    throw new UnsupportedOperationException("Not yet implemented"); // CobWeb
+    throw new UnsupportedOperationException("Not yet implemented"); //CobWeb
   }
 
+  /**
+   * Read instance.
+   *
+   * @param fileReader the file reader
+   * @return true, if successful
+   */
   public boolean readInstance(Reader fileReader) {
 
+    //ArffReader arff = new ArffReader(reader, this, m_Lines, 1);
     if (loader == null) {
       loader = new ArffLoader(fileReader, 0, this.classAttribute);
     }
-    return readInstance();
+    Instance inst = loader.readInstance();
+    if (inst != null) {
+      inst.setDataset(this);
+      add(inst);
+      return true;
+    } else {
+      return false;
+    }
   }
 
   public boolean readInstance() {
@@ -210,16 +463,37 @@
     }
   }
 
+  /**
+   * Delete.
+   */
   public void delete() {
-    this.instances = new ArrayList<>();
+    this.instances = new ArrayList<Instance>();
   }
 
+  /**
+   * Delete.
+   */
+  public void delete(int index) {
+    this.instances.remove(index);
+  }
+
+  /**
+   * Swap.
+   *
+   * @param i the i
+   * @param j the j
+   */
   public void swap(int i, int j) {
     Instance in = instances.get(i);
     instances.set(i, instances.get(j));
     instances.set(j, in);
   }
 
+  /**
+   * Instance information.
+   *
+   * @return the instance information
+   */
   private InstanceInformation instanceInformation() {
     return this.instanceInformation;
   }
@@ -234,32 +508,122 @@
     return null;
   }
 
-  @Override
-  public String toString() {
-    StringBuilder text = new StringBuilder();
-
-    for (int i = 0; i < numInstances(); i++) {
-      text.append(instance(i).toString());
-      if (i < numInstances() - 1) {
-        text.append('\n');
-      }
-    }
-    return text.toString();
+  public int size() {
+    return this.numInstances();
   }
 
-  // toString() with header
-  public String toStringArff() {
-    StringBuilder text = new StringBuilder();
+  public void set(int i, Instance inst) {
+    this.instances.set(i, inst);
+  }
 
-    text.append(ARFF_RELATION).append(" ")
-        .append(Utils.quote(getRelationName())).append("\n\n");
+  public Instance get(int k) {
+    return this.instance(k);
+  }
+
+  public void setRangeOutputIndices(Range range) {
+    this.instanceInformation.setRangeOutputIndices(range);
+
+  }
+
+  public void setAttributes(List<Attribute> v) {
+    if (this.instanceInformation == null) {
+      this.instanceInformation = new InstanceInformation();
+    }
+    this.instanceInformation.setAttributes(v);
+  }
+
+  public void setAttributes(List<Attribute> v, List<Integer> indexValues) {
+    if (this.instanceInformation == null) {
+      this.instanceInformation = new InstanceInformation();
+    }
+    this.instanceInformation.setAttributes(v, indexValues);
+  }
+
+  /**
+   * Returns the dataset as a string in ARFF format. Strings are quoted if
+   * they contain whitespace characters, or if they are a question mark.
+   *
+   * @return the dataset in ARFF format as a string
+   */
+  public String toString() {
+
+    StringBuffer text = new StringBuffer();
+
+    text.append(ARFF_RELATION).append(" ").
+    append(Utils.quote(this.instanceInformation.getRelationName())).append("\n\n");
     for (int i = 0; i < numAttributes(); i++) {
       text.append(attribute(i).toString()).append("\n");
     }
     text.append("\n").append(ARFF_DATA).append("\n");
 
-    text.append(toString());
+    text.append(stringWithoutHeader());
+    return text.toString();
+  }
+
+  /**
+   * Returns the dataset as a string in ARFF format. Strings are quoted if
+   * they contain whitespace characters, or if they are a question mark.
+   *
+   * @return the dataset in ARFF format as a string
+   */
+  public String toStringArff() {
+
+    StringBuffer text = new StringBuffer();
+
+    text.append(ARFF_RELATION).append(" ").
+    append(Utils.quote(this.instanceInformation.getRelationName())).append("\n\n");
+    for (int i = 0; i < numAttributes(); i++) {
+      text.append(attribute(i).toString()).append("\n");
+    }
+    text.append("\n").append(ARFF_DATA).append("\n");
+
+    text.append(stringWithoutHeader());
+    return text.toString();
+  }
+
+  /**
+   * Returns the instances in the dataset as a string in ARFF format. Strings
+   * are quoted if they contain whitespace characters, or if they are a
+   * question mark.
+   *
+   * @return the dataset in ARFF format as a string
+   */
+  protected String stringWithoutHeader() {
+
+    StringBuffer text = new StringBuffer();
+
+    for (int i = 0; i < numInstances(); i++) {
+      text.append(instance(i));
+      if (i < numInstances() - 1) {
+        text.append('\n');
+      }
+    }
     return text.toString();
 
   }
+
+  /**
+   * Returns the index of an Attribute.
+   *
+   * @param att, the attribute.
+   */
+  protected int indexOf(Attribute att) {
+    if (this.hsAttributesIndices == null || !this.hsAttributesIndices.containsKey(att.name)) {
+      computeAttributesIndices();
+    }
+
+    return this.hsAttributesIndices.get(att.name());
+  }
+
+  /**
+   * Completes the hashset with attributes indices.
+   */
+  private void computeAttributesIndices() {
+    this.hsAttributesIndices = new HashMap<String, Integer>();
+    // iterates through all existing attributes
+    // and sets an unique identifier for each one of them
+    for (int i = 0; i < this.numAttributes(); i++) {
+      hsAttributesIndices.put(this.attribute(i).name(), i);
+    }
+  }
 }
diff --git a/samoa-instances/src/main/java/org/apache/samoa/instances/InstancesHeader.java b/samoa-instances/src/main/java/org/apache/samoa/instances/InstancesHeader.java
index a5d5a74..c32cf88 100644
--- a/samoa-instances/src/main/java/org/apache/samoa/instances/InstancesHeader.java
+++ b/samoa-instances/src/main/java/org/apache/samoa/instances/InstancesHeader.java
@@ -20,12 +20,6 @@
  * #L%
  */
 
-/**
- * Class for storing the header or context of a data stream. It allows to know the number of attributes and classes.
- * 
- * @author Richard Kirkby (rkirkby@cs.waikato.ac.nz)
- * @version $Revision: 7 $
- */
 public class InstancesHeader extends Instances {
 
   private static final long serialVersionUID = 1L;
@@ -38,14 +32,6 @@
     super();
   }
 
-  /*
-   * @Override public boolean add(Instance i) { throw new
-   * UnsupportedOperationException(); }
-   * 
-   * @Override public boolean readInstance(Reader r) throws IOException { throw
-   * new UnsupportedOperationException(); }
-   */
-
   public static String getClassNameString(InstancesHeader context) {
     if (context == null) {
       return "[class]";
@@ -59,7 +45,7 @@
       return "<class " + (classLabelIndex + 1) + ">";
     }
     return "<class " + (classLabelIndex + 1) + ":"
-        + context.classAttribute().value(classLabelIndex) + ">";
+    + context.classAttribute().value(classLabelIndex) + ">";
   }
 
   // is impervious to class index changes - attIndex is true attribute index
@@ -72,7 +58,17 @@
     int instAttIndex = attIndex < context.classIndex() ? attIndex
         : attIndex + 1;
     return "[att " + (attIndex + 1) + ":"
-        + context.attribute(instAttIndex).name() + "]";
+    + context.attribute(instAttIndex).name() + "]";
+  }
+
+  public static String getInputAttributeNameString(InstancesHeader context,
+      int attIndex) {
+    if ((context == null) || (attIndex >= context.numInputAttributes())) {
+      return "[att " + (attIndex + 1) + "]";
+    }
+    int instAttIndex = attIndex;
+    return "[att " + (attIndex + 1) + ":"
+    + context.inputAttribute(instAttIndex).name() + "]";
   }
 
   // is impervious to class index changes - attIndex is true attribute index
@@ -107,17 +103,23 @@
     return Double.toString(value);
   }
 
-  // add autom.
-  /*
-   * public int classIndex() { throw new
-   * UnsupportedOperationException("Not yet implemented"); }
-   * 
-   * public int numAttributes() { throw new
-   * UnsupportedOperationException("Not yet implemented"); }
-   * 
-   * @Override public Attribute attribute(int nPos) { throw new
-   * UnsupportedOperationException("Not yet implemented"); }
-   * 
-   * public int numClasses() { return 0; }
-   */
+  public Attribute inputAttribute(int w) {
+    return this.instanceInformation.inputAttribute(w);
+  }
+
+  public Attribute outputAttribute(int w) {
+    return this.instanceInformation.outputAttribute(w);
+  }
+
+  public int numInputAttributes() {
+    return this.instanceInformation.numInputAttributes();
+  }
+
+  public int numOutputAttributes() {
+    return this.instanceInformation.numOutputAttributes();
+  }
+
+  public InstanceInformation getInstanceInformation() {
+    return this.instanceInformation;
+  }
 }
diff --git a/samoa-instances/src/main/java/org/apache/samoa/instances/Loader.java b/samoa-instances/src/main/java/org/apache/samoa/instances/Loader.java
index 7e04fbb..65835f1 100644
--- a/samoa-instances/src/main/java/org/apache/samoa/instances/Loader.java
+++ b/samoa-instances/src/main/java/org/apache/samoa/instances/Loader.java
@@ -22,12 +22,6 @@
 
 import java.io.Serializable;
 
-/**
- * Loads Instances from streams of different types of Input Formats e.g ARFF & AVRO
- * 
- * @author jayadeepj
- */
-
 public interface Loader extends Serializable {
 
   /**
diff --git a/samoa-instances/src/main/java/org/apache/samoa/instances/MultiLabelInstance.java b/samoa-instances/src/main/java/org/apache/samoa/instances/MultiLabelInstance.java
new file mode 100644
index 0000000..9567c90
--- /dev/null
+++ b/samoa-instances/src/main/java/org/apache/samoa/instances/MultiLabelInstance.java
@@ -0,0 +1,25 @@
+package org.apache.samoa.instances;
+
+/*
+ * #%L
+ * SAMOA
+ * %%
+ * Copyright (C) 2014 - 2015 Apache Software Foundation
+ * %%
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * #L%
+ */
+
+public interface MultiLabelInstance extends Instance {
+
+}
diff --git a/samoa-instances/src/main/java/org/apache/samoa/instances/MultiLabelPrediction.java b/samoa-instances/src/main/java/org/apache/samoa/instances/MultiLabelPrediction.java
new file mode 100644
index 0000000..0b51c56
--- /dev/null
+++ b/samoa-instances/src/main/java/org/apache/samoa/instances/MultiLabelPrediction.java
@@ -0,0 +1,139 @@
+package org.apache.samoa.instances;
+
+/*
+ * #%L
+ * SAMOA
+ * %%
+ * Copyright (C) 2014 - 2015 Apache Software Foundation
+ * %%
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * #L%
+ */
+
+import java.io.Serializable;
+import java.util.ArrayList;
+
+public class MultiLabelPrediction implements Prediction, Serializable {
+  protected ArrayList< ArrayList<Double> > prediction;
+
+  public MultiLabelPrediction() {
+    this(0);
+  }
+
+  public MultiLabelPrediction(int numOutputAttributes) {
+    prediction = new ArrayList< ArrayList<Double> >();
+    for (int i=0; i<numOutputAttributes;i++)
+      prediction.add(new ArrayList<Double>());
+  }
+
+  @Override
+  public int numOutputAttributes() {
+    return prediction.size();
+  }
+
+  @Override
+  public int numClasses(int outputAttributeIndex) {
+    int ret = 0;
+    if (prediction.size() > outputAttributeIndex) {
+      ret =  prediction.get(outputAttributeIndex).size();
+    }
+    return ret;
+  }
+
+  @Override
+  public double[] getVotes(int outputAttributeIndex) {
+    int s = prediction.get(outputAttributeIndex).size();
+    double ret[] = null;
+    if (prediction.size() > outputAttributeIndex) {
+      ArrayList<Double> aux = prediction.get(outputAttributeIndex);
+      ret = new double[s];
+      for (int i =0;i < s;i++) {
+        ret[i] = aux.get(i).doubleValue();
+      }
+    }
+
+    return ret;
+  }
+
+  @Override
+  public double[] getVotes() {
+    return getVotes(0);
+  }
+
+  @Override
+  public double getVote(int outputAttributeIndex, int classIndex) {
+    double ret = 0.0;
+    if (prediction.size() > outputAttributeIndex) {
+      ret = (classIndex >= 0 && classIndex < prediction.get(outputAttributeIndex).size()) ?
+          prediction.get(outputAttributeIndex).get(classIndex) : 0;
+    }
+    return ret;
+  }
+
+  @Override
+  public void setVotes(int outputAttributeIndex, double[] votes) {
+    for(int i=0; i<votes.length; i++) {
+      if (i >= prediction.get(outputAttributeIndex).size()) {
+        prediction.get(outputAttributeIndex).ensureCapacity(i+1);
+        while (prediction.get(outputAttributeIndex).size() < i+1) {
+          prediction.get(outputAttributeIndex).add(0.0);
+        }
+      }
+
+      prediction.get(outputAttributeIndex).set(i,votes[i]);
+    }
+  }
+
+  @Override
+  public void setVotes(double[] votes) {
+    setVotes(0, votes);
+  }
+
+  @Override
+  public void setVote(int outputAttributeIndex, int classIndex, double vote) {
+    if (outputAttributeIndex >= prediction.get(outputAttributeIndex).size()) {
+      prediction.get(outputAttributeIndex).ensureCapacity(classIndex+1);
+      while (prediction.get(outputAttributeIndex).size() < classIndex+1) {
+        prediction.get(outputAttributeIndex).add(0.0);
+      }
+    }
+
+    prediction.get(outputAttributeIndex).set(classIndex, vote);
+  }
+
+  @Override
+  public String toString(){
+    StringBuffer sb= new StringBuffer();
+    for (int i=0; i<prediction.size(); i++){
+      sb.append("Out " + i + ": ");
+      for (int c=0; c<prediction.get(i).size(); c++)
+      {
+        sb.append(((int)(prediction.get(i).get(c)*1000)/1000.0)+ " ");
+      }
+    }
+    return sb.toString();
+  }
+
+  @Override
+  public boolean hasVotesForAttribute(int outputAttributeIndex) {
+    if(prediction.size()<(outputAttributeIndex+1))
+      return false;
+    return (prediction.get(outputAttributeIndex).size()==0) ? false : true;
+  }
+
+  @Override
+  public int size() {
+    return prediction.size();
+  }
+
+}
\ No newline at end of file
diff --git a/samoa-instances/src/main/java/org/apache/samoa/instances/MultiTargetArffLoader.java b/samoa-instances/src/main/java/org/apache/samoa/instances/MultiTargetArffLoader.java
new file mode 100644
index 0000000..0e9a8fa
--- /dev/null
+++ b/samoa-instances/src/main/java/org/apache/samoa/instances/MultiTargetArffLoader.java
@@ -0,0 +1,47 @@
+package org.apache.samoa.instances;
+
+/*
+ * #%L
+ * SAMOA
+ * %%
+ * Copyright (C) 2014 - 2015 Apache Software Foundation
+ * %%
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * #L%
+ */
+
+import java.io.Reader;
+
+public class MultiTargetArffLoader extends ArffLoader {
+
+  public MultiTargetArffLoader(Reader reader) {
+    super(reader);
+  }
+
+  public MultiTargetArffLoader(Reader reader, Range range) {
+    super(reader, range);
+  }
+
+  @Override
+  protected Instance newSparseInstance(double d, double[] res) {
+    return new SparseInstance(d, res); // TODO
+  }
+
+  @Override
+  protected Instance newDenseInstance(int numAttributes) {
+    // numAttributes is this.instanceInformation.numAttributes()
+    this.range.setUpper(numAttributes);
+    return new DenseInstance(numAttributes);
+  }
+  
+}
diff --git a/samoa-instances/src/main/java/org/apache/samoa/instances/Prediction.java b/samoa-instances/src/main/java/org/apache/samoa/instances/Prediction.java
new file mode 100644
index 0000000..059e912
--- /dev/null
+++ b/samoa-instances/src/main/java/org/apache/samoa/instances/Prediction.java
@@ -0,0 +1,110 @@
+package org.apache.samoa.instances;
+
+/*
+ * #%L
+ * SAMOA
+ * %%
+ * Copyright (C) 2014 - 2015 Apache Software Foundation
+ * %%
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * #L%
+ */
+
+public interface Prediction {
+
+  /**
+   * Number of output attributes.
+   *
+   * @return the number of output attributes
+   */
+  public int numOutputAttributes();
+
+  /**
+   * Different output attributes may have different number of classes.
+   * Regressors have one class per output attribute.
+   *
+   * @return the number of classes for attribute attributeIndex
+   */
+  public int numClasses(int outputAttributeIndex);
+
+  /*
+   * The predictions for each output attribute.
+   *
+   * @return the classes for each output attribute
+   *//*
+	public double [] getPrediction();
+    */
+
+  /**
+   * The votes for a given output attribute
+   *
+   * @return the votes for a given output attribute outputAttributeIndex.
+   */
+  public double [] getVotes(int outputAttributeIndex);
+
+  /**
+   * The vote assigned to a class of an output attribute
+   *
+   * @return the vote for an output attribute outputAttributeIndex and a class classIndex.
+   */
+  public double getVote(int outputAttributeIndex, int classIndex);
+
+  /**
+   * Sets the votes for a given output attribute
+   *
+   */
+  public void setVotes(int outputAttributeIndex, double [] votes);
+
+  /**
+   * Sets the votes for the first output attribute
+   *
+   */
+  public void setVotes(double[] votes);
+
+  /**
+   * Sets the vote for class of a given output attribute
+   *
+   */
+  public void setVote(int outputAttributeIndex, int classIndex, double vote);
+
+  /**
+   * The votes for the first output attribute
+   *
+   * @return the votes for the first output attribute outputAttributeIndex.
+   */
+  double[] getVotes();
+
+  /**
+   * Checks if there are votes for a given output attribute
+   *
+   * @return the votes for the first output attribute outputAttributeIndex.
+   */
+  boolean hasVotesForAttribute(int outputAttributeIndex);
+
+
+  /**
+   * The size of the prediction, that is the number of output attributes
+   *
+   * @return the votes for the first output attribute outputAttributeIndex.
+   */
+  public int size();
+
+  /**
+   * The text of the prediction, that is the description of the values of the prediction
+   *
+   * @return the text
+   */
+  public String toString();
+
+
+}
diff --git a/samoa-instances/src/main/java/org/apache/samoa/instances/Range.java b/samoa-instances/src/main/java/org/apache/samoa/instances/Range.java
new file mode 100644
index 0000000..52d036f
--- /dev/null
+++ b/samoa-instances/src/main/java/org/apache/samoa/instances/Range.java
@@ -0,0 +1,114 @@
+package org.apache.samoa.instances;
+
+/*
+ * #%L
+ * SAMOA
+ * %%
+ * Copyright (C) 2014 - 2015 Apache Software Foundation
+ * %%
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * #L%
+ */
+
+import java.io.Serializable;
+
+public class Range implements Serializable {
+
+  //Only works for ranges "start-end"
+  private int start = 0;
+  private int end = 0;
+  private int upperLimit = 0;
+  private final String rangeText;
+
+  public Range(String range) {
+    this.rangeText = range;
+    //this.setRange(range); //needs upperLimit
+  }
+
+  /**
+   * Sets the range from a string representation.
+   *
+   * @param range the start and end string
+   *
+   */
+  public void setRange(String range) {
+    String single = range.trim();
+    int hyphenIndex = range.indexOf('-');
+
+    if (hyphenIndex > 0) {
+      this.start = rangeSingle(range.substring(0, hyphenIndex));
+      this.end = rangeSingle(range.substring(hyphenIndex + 1));
+    } else {
+      int number = rangeSingle(range);
+      if (number >= 0) { // first n attributes
+        this.start = 0;
+        this.end = number;
+      } else { // last n attributes
+        this.start = this.upperLimit + number > 0 ? this.upperLimit + number : 0;
+        this.end = this.upperLimit - 1;
+      }
+    }
+  }
+
+  /**
+   * Translates a single string selection into it's internal 0-based
+   * equivalent.
+   *
+   * @param single the string representing the selection (eg: 1 first last)
+   * @return the number corresponding to the selected value
+   */
+  protected /*@pure@*/ int rangeSingle(/*@non_null@*/String singleSelection) {
+
+    String single = singleSelection.trim();
+    if (single.toLowerCase().equals("first")) {
+      return 0;
+    }
+    if (single.toLowerCase().equals("last") || single.toLowerCase().equals("-1")) {
+      return -1;
+    }
+    int index = Integer.parseInt(single);
+    if (index >= 1) { //Non for negatives
+      index--;
+    }
+    return index;
+  }
+
+  boolean isInRange(int value) {
+    boolean ret = false;
+    if (value >= start && value <= end) {
+      ret = true;
+    }
+    return ret;
+  }
+
+  int getSelectionLength() {
+    return end - start + 1;
+  }
+
+  public void setUpper(int attributeNumber) {
+    this.upperLimit = attributeNumber;
+    this.setRange(this.rangeText);
+  }
+
+  //JD
+  public int getStart() {
+    return start;
+  }
+
+  //JD
+
+  public int getEnd() {
+    return end;
+  }
+
+}
diff --git a/samoa-instances/src/main/java/org/apache/samoa/instances/SingleClassInstanceData.java b/samoa-instances/src/main/java/org/apache/samoa/instances/SingleClassInstanceData.java
deleted file mode 100644
index dfb8474..0000000
--- a/samoa-instances/src/main/java/org/apache/samoa/instances/SingleClassInstanceData.java
+++ /dev/null
@@ -1,86 +0,0 @@
-/*
- * To change this template, choose Tools | Templates
- * and open the template in the editor.
- */
-package org.apache.samoa.instances;
-
-/*
- * #%L
- * SAMOA
- * %%
- * Copyright (C) 2014 - 2015 Apache Software Foundation
- * %%
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- * 
- *      http://www.apache.org/licenses/LICENSE-2.0
- * 
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- * #L%
- */
-
-/**
- * 
- * @author abifet
- */
-public class SingleClassInstanceData implements InstanceData {
-
-  protected double classValue;
-
-  @Override
-  public int numAttributes() {
-    return 1;
-  }
-
-  @Override
-  public double value(int instAttIndex) {
-    return classValue;
-  }
-
-  @Override
-  public boolean isMissing(int indexAttribute) {
-    return Double.isNaN(this.value(indexAttribute));
-  }
-
-  @Override
-  public int numValues() {
-    return 1;
-  }
-
-  @Override
-  public int index(int i) {
-    return 0;
-  }
-
-  @Override
-  public double valueSparse(int i) {
-    return value(i);
-  }
-
-  @Override
-  public boolean isMissingSparse(int indexAttribute) {
-    return Double.isNaN(this.value(indexAttribute));
-  }
-
-  /*
-   * @Override public double value(Attribute attribute) { return
-   * this.classValue; }
-   */
-
-  @Override
-  public double[] toDoubleArray() {
-    double[] array = { this.classValue };
-    return array;
-  }
-
-  @Override
-  public void setValue(int m_numAttributes, double d) {
-    this.classValue = d;
-  }
-
-}
diff --git a/samoa-instances/src/main/java/org/apache/samoa/instances/SingleLabelInstance.java b/samoa-instances/src/main/java/org/apache/samoa/instances/SingleLabelInstance.java
deleted file mode 100644
index d69a0f5..0000000
--- a/samoa-instances/src/main/java/org/apache/samoa/instances/SingleLabelInstance.java
+++ /dev/null
@@ -1,260 +0,0 @@
-/*
- * To change this template, choose Tools | Templates
- * and open the template in the editor.
- */
-package org.apache.samoa.instances;
-
-/*
- * #%L
- * SAMOA
- * %%
- * Copyright (C) 2014 - 2015 Apache Software Foundation
- * %%
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- * 
- *      http://www.apache.org/licenses/LICENSE-2.0
- * 
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- * #L%
- */
-
-/**
- * 
- * @author abifet
- */
-// public int[] m_AttValues; // for DataPoint
-
-public class SingleLabelInstance implements Instance {
-
-  protected double weight;
-
-  protected InstanceData instanceData;
-
-  protected InstanceData classData;
-
-  // Fast implementation without using Objects
-  // protected double[] attributeValues;
-  // protected double classValue;
-
-  protected InstancesHeader instanceInformation;
-
-  public SingleLabelInstance() {
-    // necessary for kryo serializer
-  }
-
-  public SingleLabelInstance(SingleLabelInstance inst) {
-    this.weight = inst.weight;
-    this.instanceData = inst.instanceData; // copy
-    this.classData = inst.classData; // copy
-    // this.classValue = inst.classValue;
-    // this.attributeValues = inst.attributeValues;
-    this.instanceInformation = inst.instanceInformation;
-  }
-
-  // Dense
-  public SingleLabelInstance(double weight, double[] res) {
-    this.weight = weight;
-    this.instanceData = new DenseInstanceData(res);
-    // this.attributeValues = res;
-    this.classData = new SingleClassInstanceData();
-    // this.classValue = Double.NaN;
-
-  }
-
-  // Sparse
-  public SingleLabelInstance(double weight, double[] attributeValues,
-      int[] indexValues, int numberAttributes) {
-    this.weight = weight;
-    this.instanceData = new SparseInstanceData(attributeValues,
-        indexValues, numberAttributes); // ???
-    this.classData = new SingleClassInstanceData();
-    // this.classValue = Double.NaN;
-    // this.instanceInformation = new InstancesHeader();
-
-  }
-
-  public SingleLabelInstance(double weight, InstanceData instanceData) {
-    this.weight = weight;
-    this.instanceData = instanceData; // ???
-    // this.classValue = Double.NaN;
-    this.classData = new SingleClassInstanceData();
-    // this.instanceInformation = new InstancesHeader();
-  }
-
-  public SingleLabelInstance(int numAttributes) {
-    this.instanceData = new DenseInstanceData(new double[numAttributes]);
-    // m_AttValues = new double[numAttributes];
-    /*
-     * for (int i = 0; i < m_AttValues.length; i++) { m_AttValues[i] =
-     * Utils.missingValue(); }
-     */
-    this.weight = 1;
-    this.classData = new SingleClassInstanceData();
-    this.instanceInformation = new InstancesHeader();
-  }
-
-  @Override
-  public double weight() {
-    return weight;
-  }
-
-  @Override
-  public void setWeight(double weight) {
-    this.weight = weight;
-  }
-
-  @Override
-  public Attribute attribute(int instAttIndex) {
-    return this.instanceInformation.attribute(instAttIndex);
-  }
-
-  @Override
-  public void deleteAttributeAt(int i) {
-    // throw new UnsupportedOperationException("Not yet implemented");
-  }
-
-  @Override
-  public void insertAttributeAt(int i) {
-    throw new UnsupportedOperationException("Not yet implemented");
-  }
-
-  @Override
-  public int numAttributes() {
-    return this.instanceInformation.numAttributes();
-  }
-
-  @Override
-  public double value(int instAttIndex) {
-    return // attributeValues[instAttIndex]; //
-    this.instanceData.value(instAttIndex);
-  }
-
-  @Override
-  public boolean isMissing(int instAttIndex) {
-    return // Double.isNaN(value(instAttIndex)); //
-    this.instanceData.isMissing(instAttIndex);
-  }
-
-  @Override
-  public int numValues() {
-    return // this.attributeValues.length; //
-    this.instanceData.numValues();
-  }
-
-  @Override
-  public int index(int i) {
-    return // i; //
-    this.instanceData.index(i);
-  }
-
-  @Override
-  public double valueSparse(int i) {
-    return this.instanceData.valueSparse(i);
-  }
-
-  @Override
-  public boolean isMissingSparse(int p) {
-    return this.instanceData.isMissingSparse(p);
-  }
-
-  @Override
-  public double value(Attribute attribute) {
-    // throw new UnsupportedOperationException("Not yet implemented");
-    // //Predicates.java
-    return value(attribute.index());
-
-  }
-
-  @Override
-  public String stringValue(int i) {
-    throw new UnsupportedOperationException("Not yet implemented");
-  }
-
-  @Override
-  public double[] toDoubleArray() {
-    return // this.attributeValues; //
-    this.instanceData.toDoubleArray();
-  }
-
-  @Override
-  public void setValue(int numAttribute, double d) {
-    this.instanceData.setValue(numAttribute, d);
-    // this.attributeValues[numAttribute] = d;
-  }
-
-  @Override
-  public double classValue() {
-    return this.classData.value(0);
-    // return classValue;
-  }
-
-  @Override
-  public int classIndex() {
-    return instanceInformation.classIndex();
-  }
-
-  @Override
-  public int numClasses() {
-    return this.instanceInformation.numClasses();
-  }
-
-  @Override
-  public boolean classIsMissing() {
-    return // Double.isNaN(this.classValue);//
-    this.classData.isMissing(0);
-  }
-
-  @Override
-  public Attribute classAttribute() {
-    //return the class attribute
-    return this.instanceInformation.attribute(classIndex());
-  }
-
-  @Override
-  public void setClassValue(double d) {
-    this.classData.setValue(0, d);
-  }
-
-  @Override
-  public Instance copy() {
-    SingleLabelInstance inst = new SingleLabelInstance(this);
-    return inst;
-  }
-
-  @Override
-  public Instances dataset() {
-    return this.instanceInformation;
-  }
-
-  @Override
-  public void setDataset(Instances dataset) {
-    this.instanceInformation = new InstancesHeader(dataset);
-  }
-
-  public void addSparseValues(int[] indexValues, double[] attributeValues,
-      int numberAttributes) {
-    this.instanceData = new SparseInstanceData(attributeValues,
-        indexValues, numberAttributes); // ???
-  }
-
-  @Override
-  public String toString() {
-    StringBuffer text = new StringBuffer();
-
-    for (int i = 0; i < this.numValues(); i++) {
-      if (i > 0)
-        text.append(",");
-      text.append(this.value(i));
-    }
-    text.append(",").append(this.weight());
-
-    return text.toString();
-  }
-
-}
diff --git a/samoa-instances/src/main/java/org/apache/samoa/instances/SparseInstance.java b/samoa-instances/src/main/java/org/apache/samoa/instances/SparseInstance.java
index 56dbc7f..a62013a 100644
--- a/samoa-instances/src/main/java/org/apache/samoa/instances/SparseInstance.java
+++ b/samoa-instances/src/main/java/org/apache/samoa/instances/SparseInstance.java
@@ -1,7 +1,3 @@
-/*
- * To change this template, choose Tools | Templates
- * and open the template in the editor.
- */
 package org.apache.samoa.instances;
 
 /*
@@ -24,63 +20,46 @@
  * #L%
  */
 
-import java.text.SimpleDateFormat;
+public class SparseInstance extends InstanceImpl {
 
-/**
- * 
- * @author abifet
- */
-public class SparseInstance extends SingleLabelInstance {
-
+  /**
+   * Instantiates a new sparse instance.
+   *
+   * @param d the d
+   * @param res the res
+   */
   public SparseInstance(double d, double[] res) {
     super(d, res);
   }
 
-  public SparseInstance(SingleLabelInstance inst) {
+  /**
+   * Instantiates a new sparse instance.
+   *
+   * @param inst the inst
+   */
+  public SparseInstance(InstanceImpl inst) {
     super(inst);
   }
 
+  /**
+   * Instantiates a new sparse instance.
+   *
+   * @param numberAttributes the number attributes
+   */
   public SparseInstance(double numberAttributes) {
-    // super(1, new double[(int) numberAttributes-1]);
     super(1, null, null, (int) numberAttributes);
   }
 
+  /**
+   * Instantiates a new sparse instance.
+   *
+   * @param weight the weight
+   * @param attributeValues the attribute values
+   * @param indexValues the index values
+   * @param numberAttributes the number attributes
+   */
   public SparseInstance(double weight, double[] attributeValues, int[] indexValues, int numberAttributes) {
     super(weight, attributeValues, indexValues, numberAttributes);
   }
 
-  @Override
-  public String toString() {
-    StringBuffer str = new StringBuffer();
-
-    str.append("{");
-
-    for (int i=0; i<this.numAttributes()-1;i++){
-      if (!this.isMissing(i)) {
-
-        //if the attribute is Nominal we print the string value of the attribute.
-        if (this.attribute(i).isNominal()) {
-          int valueIndex = (int) this.value(i);
-          String stringValue = this.attribute(i).value(valueIndex);
-          str.append(i).append(" ").append(stringValue).append(",");
-        } else if (this.attribute(i).isNumeric()) {
-          //if the attribute is numeric we print the value of the attribute only if it is not equal 0
-          if (this.value(i) != 0) {
-            str.append(i).append(" ").append(this.value(i)).append(",");
-          }
-        } else if (this.attribute(i).isDate()) {
-          SimpleDateFormat dateFormatter = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss");
-          str.append(i).append(" ").append(dateFormatter.format(this.value(i))).append(",");
-        }
-      } else { //represent missing values
-        str.append(i).append(" ").append("?,");
-      }
-    }
-    //append the class value at the end of the instance.
-    str.append(classIndex()).append(" ").append(this.classAttribute().value((int)classValue()));
-
-    str.append("}");
-
-    return str.toString();
-  }
 }
diff --git a/samoa-instances/src/main/java/org/apache/samoa/instances/SparseInstanceData.java b/samoa-instances/src/main/java/org/apache/samoa/instances/SparseInstanceData.java
index 9c14b8f..77b634b 100644
--- a/samoa-instances/src/main/java/org/apache/samoa/instances/SparseInstanceData.java
+++ b/samoa-instances/src/main/java/org/apache/samoa/instances/SparseInstanceData.java
@@ -1,7 +1,3 @@
-/*
- * To change this template, choose Tools | Templates
- * and open the template in the editor.
- */
 package org.apache.samoa.instances;
 
 /*
@@ -24,62 +20,121 @@
  * #L%
  */
 
-/**
- * 
- * @author abifet
- */
 public class SparseInstanceData implements InstanceData {
 
+  /**
+   * Instantiates a new sparse instance data.
+   *
+   * @param attributeValues the attribute values
+   * @param indexValues the index values
+   * @param numberAttributes the number attributes
+   */
   public SparseInstanceData(double[] attributeValues, int[] indexValues, int numberAttributes) {
     this.attributeValues = attributeValues;
     this.indexValues = indexValues;
     this.numberAttributes = numberAttributes;
   }
 
+  /**
+   * Instantiates a new sparse instance data.
+   *
+   * @param length the length
+   */
   public SparseInstanceData(int length) {
     this.attributeValues = new double[length];
     this.indexValues = new int[length];
   }
 
+  /**
+   * The attribute values.
+   */
   protected double[] attributeValues;
 
+  /**
+   * Gets the attribute values.
+   *
+   * @return the attribute values
+   */
   public double[] getAttributeValues() {
     return attributeValues;
   }
 
+  /**
+   * Sets the attribute values.
+   *
+   * @param attributeValues the new attribute values
+   */
   public void setAttributeValues(double[] attributeValues) {
     this.attributeValues = attributeValues;
   }
 
+  /**
+   * Gets the index values.
+   *
+   * @return the index values
+   */
   public int[] getIndexValues() {
     return indexValues;
   }
 
+  /**
+   * Sets the index values.
+   *
+   * @param indexValues the new index values
+   */
   public void setIndexValues(int[] indexValues) {
     this.indexValues = indexValues;
   }
 
+  /**
+   * Gets the number attributes.
+   *
+   * @return the number attributes
+   */
   public int getNumberAttributes() {
     return numberAttributes;
   }
 
+  /**
+   * Sets the number of attributes.
+   *
+   * @param numberAttributes the new number attributes
+   */
   public void setNumberAttributes(int numberAttributes) {
     this.numberAttributes = numberAttributes;
   }
 
+  /**
+   * The index values.
+   */
   protected int[] indexValues;
+
+  /**
+   * The number of attributes.
+   */
   protected int numberAttributes;
 
+  /**
+   * Gets the number of attributes.
+   *
+   * @return the int
+   */
   @Override
   public int numAttributes() {
     return this.numberAttributes;
   }
 
+  /**
+   * Value.
+   *
+   * @param indexAttribute the index attribute
+   * @return the double
+   */
   @Override
   public double value(int indexAttribute) {
     int location = locateIndex(indexAttribute);
-    // return location == -1 ? 0 : this.attributeValues[location];
-    // int index = locateIndex(attIndex);
+    //return location == -1 ? 0 : this.attributeValues[location];
+    //      int index = locateIndex(attIndex);
     if ((location >= 0) && (indexValues[location] == indexAttribute)) {
       return attributeValues[location];
     } else {
@@ -87,36 +142,65 @@
     }
   }
 
+  /**
+   * Checks if is missing.
+   *
+   * @param indexAttribute the index attribute
+   * @return true, if is missing
+   */
   @Override
   public boolean isMissing(int indexAttribute) {
     return Double.isNaN(this.value(indexAttribute));
   }
 
+  /**
+   * Num values.
+   *
+   * @return the int
+   */
   @Override
   public int numValues() {
     return this.attributeValues.length;
   }
 
+  /**
+   * Index.
+   *
+   * @param indexAttribute the index attribute
+   * @return the int
+   */
   @Override
   public int index(int indexAttribute) {
     return this.indexValues[indexAttribute];
   }
 
+  /**
+   * Value sparse.
+   *
+   * @param indexAttribute the index attribute
+   * @return the double
+   */
   @Override
   public double valueSparse(int indexAttribute) {
     return this.attributeValues[indexAttribute];
   }
 
+  /**
+   * Checks if is missing sparse.
+   *
+   * @param indexAttribute the index attribute
+   * @return true, if is missing sparse
+   */
   @Override
   public boolean isMissingSparse(int indexAttribute) {
     return Double.isNaN(this.valueSparse(indexAttribute));
   }
 
-  /*
-   * @Override public double value(Attribute attribute) { return
-   * value(attribute.index()); }
+  /**
+   * To double array.
+   *
+   * @return the double[]
    */
-
   @Override
   public double[] toDoubleArray() {
     double[] array = new double[numAttributes()];
@@ -126,6 +210,12 @@
     return array;
   }
 
+  /**
+   * Sets the value.
+   *
+   * @param attributeIndex the attribute index
+   * @param d the d
+   */
   @Override
   public void setValue(int attributeIndex, double d) {
     int index = locateIndex(attributeIndex);
@@ -138,8 +228,9 @@
 
   /**
    * Locates the greatest index that is not greater than the given index.
-   * 
-   * @return the internal index of the attribute index. Returns -1 if no index with this property could be found
+   *
+   * @return the internal index of the attribute index. Returns -1 if no index
+   * with this property could be found
    */
   public int locateIndex(int index) {
 
@@ -168,4 +259,46 @@
     }
   }
 
+  /**
+   * Deletes an attribute at the given position (0 to numAttributes() - 1).
+   * 
+   * @param pos the attribute's position
+   */
+  @Override
+  public void deleteAttributeAt(int position) {
+
+    int index = locateIndex(position);
+
+    this.numberAttributes--;
+    if ((index >= 0) && (indexValues[index] == position)) {
+      int[] tempIndices = new int[indexValues.length - 1];
+      double[] tempValues = new double[attributeValues.length - 1];
+      System.arraycopy(indexValues, 0, tempIndices, 0, index);
+      System.arraycopy(attributeValues, 0, tempValues, 0, index);
+      for (int i = index; i < indexValues.length - 1; i++) {
+        tempIndices[i] = indexValues[i + 1] - 1;
+        tempValues[i] = attributeValues[i + 1];
+      }
+      indexValues = tempIndices;
+      attributeValues = tempValues;
+    } else {
+      int[] tempIndices = new int[indexValues.length];
+      double[] tempValues = new double[attributeValues.length];
+      System.arraycopy(indexValues, 0, tempIndices, 0, index + 1);
+      System.arraycopy(attributeValues, 0, tempValues, 0, index + 1);
+      for (int i = index + 1; i < indexValues.length; i++) {
+        tempIndices[i] = indexValues[i] - 1;
+        tempValues[i] = attributeValues[i];
+      }
+      indexValues = tempIndices;
+      attributeValues = tempValues;
+    }
+  }
+
+  @Override
+  public InstanceData copy() {
+    return new SparseInstanceData(this.attributeValues,this.indexValues,this.numberAttributes);
+  }
+
+
 }
diff --git a/samoa-instances/src/main/java/org/apache/samoa/instances/Utils.java b/samoa-instances/src/main/java/org/apache/samoa/instances/Utils.java
index 73990bb..778f003 100644
--- a/samoa-instances/src/main/java/org/apache/samoa/instances/Utils.java
+++ b/samoa-instances/src/main/java/org/apache/samoa/instances/Utils.java
@@ -88,4 +88,4 @@
 
     return string;
   }
-}
+}
\ No newline at end of file