content: /*
   *    This program is free software; you can redistribute it and/or modify
   *    it under the terms of the GNU General Public License as published by
   *    the Free Software Foundation; either version 2 of the License, or
   *    (at your option) any later version.
   *
   *    This program is distributed in the hope that it will be useful,
   *    but WITHOUT ANY WARRANTY; without even the implied warranty of
   *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   *    GNU General Public License for more details.
   *
   *    You should have received a copy of the GNU General Public License
   *    along with this program; if not, write to the Free Software
   *    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
   */
  
  /*
   *    SparseInstance.java
   *    Copyright (C) 2000 University of Waikato, Hamilton, New Zealand
   *
   */
  
  package weka.core;
  
  import java.io.Serializable;
  import java.util.Enumeration;
  import java.util.ArrayList;
  
  /**
   * Class for storing an instance as a sparse vector. A sparse instance
   * only requires storage for those attribute values that are non-zero.
   * Since the objective is to reduce storage requirements for datasets
   * with large numbers of default values, this also includes nominal
   * attributes -- the first nominal value (i.e. that which has index 0)
   * will not require explicit storage, so rearrange your nominal attribute
   * value orderings if necessary. Missing values will be stored
   * explicitly.
   *
   * @author Eibe Frank
   * @version $Revision: 5987 $
   */
  public class SparseInstance extends AbstractInstance {
  
    /** for serialization */
    private static final long serialVersionUID = -3579051291332630149L;
  
    /** The index of the attribute associated with each stored value. */
    protected int[] m_Indices;
  
    /** The maximum number of values that can be stored. */
    protected int m_NumAttributes;
  
    /**
     * Constructor that generates a sparse instance from the given
     * instance. Reference to the dataset is set to null.
     * (ie. the instance doesn't have access to information about the
     * attribute types)
     *
     * @param instance the instance from which the attribute values
     * and the weight are to be copied
     */
    public SparseInstance(Instance instance) {
      
      m_Weight = instance.weight();
      m_Dataset = null;
      m_NumAttributes = instance.numAttributes();
      if (instance instanceof SparseInstance) {
        m_AttValues = ((SparseInstance)instance).m_AttValues;
        m_Indices = ((SparseInstance)instance).m_Indices;
      } else {
        double[] tempValues = new double[instance.numAttributes()];
        int[] tempIndices = new int[instance.numAttributes()];
        int vals = 0;
        for (int i = 0; i < instance.numAttributes(); i++) {
  	if (instance.value(i) != 0) {
  	  tempValues[vals] = instance.value(i);
  	  tempIndices[vals] = i;
  	  vals++;
  	}
        }
        m_AttValues = new double[vals];
        m_Indices = new int[vals];
        System.arraycopy(tempValues, 0, m_AttValues, 0, vals);
        System.arraycopy(tempIndices, 0, m_Indices, 0, vals);
      }
    }
  
    /**
     * Constructor that copies the info from the given instance. 
     * Reference to the dataset is set to null.
     * (ie. the instance doesn't have access to information about the
     * attribute types)
     *
     * @param instance the instance from which the attribute
     * info is to be copied 
     */
    public SparseInstance(SparseInstance instance) {
      
      m_AttValues = instance.m_AttValues;
      m_Indices = instance.m_Indices;
      m_Weight = instance.m_Weight;
      m_NumAttributes = instance.m_NumAttributes;
      m_Dataset = null;
    }
  
    /**
     * Constructor that generates a sparse instance from the given
     * parameters. Reference to the dataset is set to null.
     * (ie. the instance doesn't have access to information about the
     * attribute types)
     *
     * @param weight the instance's weight
     * @param attValues a vector of attribute values 
     */
    public SparseInstance(double weight, double[] attValues) {
      
      m_Weight = weight;
      m_Dataset = null;
      m_NumAttributes = attValues.length;
      double[] tempValues = new double[m_NumAttributes];
      int[] tempIndices = new int[m_NumAttributes];
      int vals = 0;
      for (int i = 0; i < m_NumAttributes; i++) {
        if (attValues[i] != 0) {
  	tempValues[vals] = attValues[i];
  	tempIndices[vals] = i;
  	vals++;
        }
      }
      m_AttValues = new double[vals];
      m_Indices = new int[vals];
      System.arraycopy(tempValues, 0, m_AttValues, 0, vals);
      System.arraycopy(tempIndices, 0, m_Indices, 0, vals);
    }
    
    /**
     * Constructor that inititalizes instance variable with given
     * values. Reference to the dataset is set to null. (ie. the instance
     * doesn't have access to information about the attribute types)
     * Note that the indices need to be sorted in ascending order. Otherwise
     * things won't work properly.
     *
     * @param weight the instance's weight
     * @param attValues a vector of attribute values (just the ones to be stored)
     * @param indices the indices of the given values in the full vector (need to
     * be sorted in ascending order)
     * @param maxNumValues the maximium number of values that can be stored
     */
    public SparseInstance(double weight, double[] attValues,
  			int[] indices, int maxNumValues){
      
      int vals = 0; 
      m_AttValues = new double [attValues.length];
      m_Indices = new int [indices.length];
      for (int i = 0; i < attValues.length; i++) {
        if (attValues[i] != 0) {
          m_AttValues[vals] = attValues[i];
          m_Indices[vals] = indices[i];
          vals++;
        }
      }
      if (vals != attValues.length) {
        // Need to truncate.
        double [] newVals = new double[vals];
        System.arraycopy(m_AttValues, 0, newVals, 0, vals);
        m_AttValues = newVals;
        int [] newIndices = new int[vals];
        System.arraycopy(m_Indices, 0, newIndices, 0, vals);
        m_Indices = newIndices;
      }
      m_Weight = weight;
      m_NumAttributes = maxNumValues;
      m_Dataset = null;
    }
  
    /**
     * Constructor of an instance that sets weight to one, all values to
     * be missing, and the reference to the dataset to null. (ie. the instance
     * doesn't have access to information about the attribute types)
     *
     * @param numAttributes the size of the instance 
     */
    public SparseInstance(int numAttributes) {
      
      m_AttValues = new double[numAttributes];
      m_NumAttributes = numAttributes;
      m_Indices = new int[numAttributes];
      for (int i = 0; i < m_AttValues.length; i++) {
        m_AttValues[i] = Utils.missingValue();
        m_Indices[i] = i;
      }
      m_Weight = 1;
      m_Dataset = null;
    }
  
    /**
     * Produces a shallow copy of this instance. The copy has
     * access to the same dataset. (if you want to make a copy
     * that doesn't have access to the dataset, use 
     * <code>new SparseInstance(instance)</code>
     *
     * @return the shallow copy
     */
    public Object copy() {
  
      SparseInstance result = new SparseInstance(this);
      result.m_Dataset = m_Dataset;
      return result;
    }
  
    /**
     * Returns the index of the attribute stored at the given position.
     *
     * @param position the position 
     * @return the index of the attribute stored at the given position
     */
    public int index(int position) {
  
      return m_Indices[position];
    }
  
    /**
     * 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, max = m_Indices.length - 1;
  
      if (max == -1) {
        return -1;
      }
  
      // Binary search
      while ((m_Indices[min] <= index) && (m_Indices[max] >= index)) {
        int current = (max + min) / 2;
        if (m_Indices[current] > index) {
  	max = current - 1;
        } else if (m_Indices[current] < index) {
  	min = current + 1;
        } else {
  	return current;
        }
      }
      if (m_Indices[max] < index) {
        return max;
      } else {
        return min - 1;
      }
    }
  
    /**
     * Merges this instance with the given instance and returns
     * the result. Dataset is set to null.
     *
     * @param inst the instance to be merged with this one
     * @return the merged instances
     */
    public Instance mergeInstance(Instance inst) {
  
      double[] values = new double[numValues() + inst.numValues()];
      int[] indices = new int[numValues() + inst.numValues()];
  
      int m = 0;
      for (int j = 0; j < numValues(); j++, m++) {
        values[m] = valueSparse(j);
        indices[m] = index(j);
      }
      for (int j = 0; j < inst.numValues(); j++, m++) {
        values[m] = inst.valueSparse(j);
        indices[m] = numAttributes() + inst.index(j);
      }
      
      return new SparseInstance(1.0, values, indices, numAttributes() +
  			      inst.numAttributes());
    }
  
    /**
     * Returns the number of attributes.
     *
     * @return the number of attributes as an integer
     */
    public int numAttributes() {
  
      return m_NumAttributes;
    }
  
    /**
     * Returns the number of values in the sparse vector.
     *
     * @return the number of values
     */
    public int numValues() {
  
      return m_Indices.length;
    }
  
    /** 
     * Replaces all missing values in the instance with the 
     * values contained in the given array. A deep copy of
     * the vector of attribute values is performed before the
     * values are replaced.
     *
     * @param array containing the means and modes
     * @exception IllegalArgumentException if numbers of attributes are unequal
     */
    public void replaceMissingValues(double[] array) {
  	 
      if ((array == null) || (array.length != m_NumAttributes)) {
        throw new IllegalArgumentException("Unequal number of attributes!");
      }
      double[] tempValues = new double[m_AttValues.length];
      int[] tempIndices = new int[m_AttValues.length];
      int vals = 0;
      for (int i = 0; i < m_AttValues.length; i++) {
        if (isMissingSparse(i)) {
  	if (array[m_Indices[i]] != 0) {
  	  tempValues[vals] = array[m_Indices[i]];
  	  tempIndices[vals] = m_Indices[i];
  	  vals++;
  	} 
        } else {
  	tempValues[vals] = m_AttValues[i];
  	tempIndices[vals] = m_Indices[i];
  	vals++;
        }
      }
      m_AttValues = new double[vals];
      m_Indices = new int[vals];
      System.arraycopy(tempValues, 0, m_AttValues, 0, vals);
      System.arraycopy(tempIndices, 0, m_Indices, 0, vals);
    }
  
    /**
     * Sets a specific value in the instance to the given value 
     * (internal floating-point format). Performs a deep copy
     * of the vector of attribute values before the value is set.
     *
     * @param attIndex the attribute's index 
     * @param value the new attribute value (If the corresponding
     * attribute is nominal (or a string) then this is the new value's
     * index as a double).  
     */
    public void setValue(int attIndex, double value) {
  
      int index = locateIndex(attIndex);
      
      if ((index >= 0) && (m_Indices[index] == attIndex)) {
        if (value != 0) {
  	double[] tempValues = new double[m_AttValues.length];
  	System.arraycopy(m_AttValues, 0, tempValues, 0, m_AttValues.length);
  	tempValues[index] = value;
  	m_AttValues = tempValues;
        } else {
  	double[] tempValues = new double[m_AttValues.length - 1];
  	int[] tempIndices = new int[m_Indices.length - 1];
  	System.arraycopy(m_AttValues, 0, tempValues, 0, index);
  	System.arraycopy(m_Indices, 0, tempIndices, 0, index);
  	System.arraycopy(m_AttValues, index + 1, tempValues, index, 
  			 m_AttValues.length - index - 1);
  	System.arraycopy(m_Indices, index + 1, tempIndices, index, 
  			 m_Indices.length - index - 1);
  	m_AttValues = tempValues;
  	m_Indices = tempIndices;
        }
      } else {
        if (value != 0) {
  	double[] tempValues = new double[m_AttValues.length + 1];
  	int[] tempIndices = new int[m_Indices.length + 1];
  	System.arraycopy(m_AttValues, 0, tempValues, 0, index + 1);
  	System.arraycopy(m_Indices, 0, tempIndices, 0, index + 1);
  	tempIndices[index + 1] = attIndex;
  	tempValues[index + 1] = value;
  	System.arraycopy(m_AttValues, index + 1, tempValues, index + 2, 
  			 m_AttValues.length - index - 1);
  	System.arraycopy(m_Indices, index + 1, tempIndices, index + 2, 
  			 m_Indices.length - index - 1);
  	m_AttValues = tempValues;
  	m_Indices = tempIndices;
        }
      }
    }
  
    /**
     * Sets a specific value in the instance to the given value 
     * (internal floating-point format). Performs a deep copy
     * of the vector of attribute values before the value is set.
     *
     * @param indexOfIndex the index of the attribute's index 
     * @param value the new attribute value (If the corresponding
     * attribute is nominal (or a string) then this is the new value's
     * index as a double).  
     */
    public void setValueSparse(int indexOfIndex, double value) {
  
      if (value != 0) {
        double[] tempValues = new double[m_AttValues.length];
        System.arraycopy(m_AttValues, 0, tempValues, 0, m_AttValues.length);
        m_AttValues = tempValues;
        m_AttValues[indexOfIndex] = value;
      } else {
        double[] tempValues = new double[m_AttValues.length - 1];
        int[] tempIndices = new int[m_Indices.length - 1];
        System.arraycopy(m_AttValues, 0, tempValues, 0, indexOfIndex);
        System.arraycopy(m_Indices, 0, tempIndices, 0, indexOfIndex);
        System.arraycopy(m_AttValues, indexOfIndex + 1, tempValues, indexOfIndex, 
  		       m_AttValues.length - indexOfIndex - 1);
        System.arraycopy(m_Indices, indexOfIndex + 1, tempIndices, indexOfIndex, 
  		       m_Indices.length - indexOfIndex - 1);
        m_AttValues = tempValues;
        m_Indices = tempIndices;
      }
    }
    
    /**
     * Returns the values of each attribute as an array of doubles.
     *
     * @return an array containing all the instance attribute values
     */
    public double[] toDoubleArray() {
  
      double[] newValues = new double[m_NumAttributes];
      for (int i = 0; i < m_AttValues.length; i++) {
        newValues[m_Indices[i]] = m_AttValues[i];
      }
      return newValues;
    }
  
    /**
     * Returns the description of one instance in sparse format. 
     * If the instance doesn't have access to a dataset, it returns the 
     * internal floating-point values. Quotes string values that contain 
     * whitespace characters.
     *
     * @return the instance's description as a string
     */
    public String toStringNoWeight() {
  
      StringBuffer text = new StringBuffer();
      
      text.append('{');
      for (int i = 0; i < m_Indices.length; i++) {
        if (i > 0) text.append(",");
        if (isMissingSparse(i)) {
  	text.append(m_Indices[i] + " ?");
        } else {
  	if (m_Dataset == null) {
  	  text.append(m_Indices[i] + " " + 
  		      Utils.doubleToString(m_AttValues[i],6));
  	} else {
  	  if (m_Dataset.attribute(m_Indices[i]).isNominal() || 
  	      m_Dataset.attribute(m_Indices[i]).isString() ||
  	      m_Dataset.attribute(m_Indices[i]).isDate()) {
  	    try {
  	      text.append(m_Indices[i] + " " +
  		  Utils.quote(stringValue(m_Indices[i])));
  	    } catch (Exception e) {
                e.printStackTrace();
                System.err.println(new Instances(m_Dataset, 0));
                System.err.println("Att:" + m_Indices[i] + " Val:" + valueSparse(i));
  	      throw new Error("This should never happen!");
  	    }
  	  } else if (m_Dataset.attribute(m_Indices[i]).isRelationValued()) {
  	    try {
  	      text.append(m_Indices[i] + " " +
  			  Utils.quote(m_Dataset.attribute(m_Indices[i]).
  				      relation((int)valueSparse(i)).
                                        stringWithoutHeader()));
              } catch (Exception e) {
                e.printStackTrace();
                System.err.println(new Instances(m_Dataset, 0));
                System.err.println("Att:" + m_Indices[i] + " Val:" + valueSparse(i));
  	      throw new Error("This should never happen!");
  	    }
  	  } else {
  	    text.append(m_Indices[i] + " " +
  			Utils.doubleToString(m_AttValues[i],6));
  	  }
  	}
        }
      }
      text.append('}');
  
      return text.toString();
    }
  
    /**
     * Returns an instance's attribute value in internal format.
     *
     * @param attIndex the attribute's index
     * @return the specified value as a double (If the corresponding
     * attribute is nominal (or a string) then it returns the value's index as a 
     * double).
     */
    public double value(int attIndex) {
  
      int index = locateIndex(attIndex);
      if ((index >= 0) && (m_Indices[index] == attIndex)) {
        return m_AttValues[index];
      } else {
        return 0.0;
      }
    }  
  
    /**
     * Deletes an attribute at the given position (0 to 
     * numAttributes() - 1).
     *
     * @param pos the attribute's position
     */
    protected void forceDeleteAttributeAt(int position) {
  
      int index = locateIndex(position);
  
      m_NumAttributes--;
      if ((index >= 0) && (m_Indices[index] == position)) {
        int[] tempIndices = new int[m_Indices.length - 1];
        double[] tempValues = new double[m_AttValues.length - 1];
        System.arraycopy(m_Indices, 0, tempIndices, 0, index);
        System.arraycopy(m_AttValues, 0, tempValues, 0, index);
        for (int i = index; i < m_Indices.length - 1; i++) {
  	tempIndices[i] = m_Indices[i + 1] - 1;
  	tempValues[i] = m_AttValues[i + 1];
        }
        m_Indices = tempIndices;
        m_AttValues = tempValues;
      } else {
        int[] tempIndices = new int[m_Indices.length];
        double[] tempValues = new double[m_AttValues.length];
        System.arraycopy(m_Indices, 0, tempIndices, 0, index + 1);
        System.arraycopy(m_AttValues, 0, tempValues, 0, index + 1);
        for (int i = index + 1; i < m_Indices.length; i++) {
  	tempIndices[i] = m_Indices[i] - 1;
  	tempValues[i] = m_AttValues[i];
        }
        m_Indices = tempIndices;
        m_AttValues = tempValues;
      }
    }
  
    /**
     * Inserts an attribute at the given position
     * (0 to numAttributes()) and sets its value to be missing. 
     *
     * @param pos the attribute's position
     */
    protected void forceInsertAttributeAt(int position)  {
  
      int index = locateIndex(position);
  
      m_NumAttributes++;
      if ((index >= 0) && (m_Indices[index] == position)) {
        int[] tempIndices = new int[m_Indices.length + 1];
        double[] tempValues = new double[m_AttValues.length + 1];
        System.arraycopy(m_Indices, 0, tempIndices, 0, index);
        System.arraycopy(m_AttValues, 0, tempValues, 0, index);
        tempIndices[index] = position;
        tempValues[index] = Utils.missingValue();
        for (int i = index; i < m_Indices.length; i++) {
  	tempIndices[i + 1] = m_Indices[i] + 1;
  	tempValues[i + 1] = m_AttValues[i];
        }
        m_Indices = tempIndices;
        m_AttValues = tempValues;
      } else {
        int[] tempIndices = new int[m_Indices.length + 1];
        double[] tempValues = new double[m_AttValues.length + 1];
        System.arraycopy(m_Indices, 0, tempIndices, 0, index + 1);
        System.arraycopy(m_AttValues, 0, tempValues, 0, index + 1);
        tempIndices[index + 1] = position;
        tempValues[index + 1] = Utils.missingValue();
        for (int i = index + 1; i < m_Indices.length; i++) {
  	tempIndices[i + 1] = m_Indices[i] + 1;
  	tempValues[i + 1] = m_AttValues[i];
        }
        m_Indices = tempIndices;
        m_AttValues = tempValues;
      }
    }
  
    /**
     * Constructor for sub classes.
     */
    protected SparseInstance() {};
  
    /**
     * Main method for testing this class.
     */
    public static void main(String[] options) {
  
      try {
  
        // Create numeric attributes "length" and "weight"
        Attribute length = new Attribute("length");
        Attribute weight = new Attribute("weight");
        
        // Create vector to hold nominal values "first", "second", "third" 
        ArrayList<String> my_nominal_values = new ArrayList<String>(3); 
        my_nominal_values.add("first"); 
        my_nominal_values.add("second"); 
        my_nominal_values.add("third"); 
        
        // Create nominal attribute "position" 
        Attribute position = new Attribute("position", my_nominal_values);
        
        // Create vector of the above attributes 
        ArrayList<Attribute> attributes = new ArrayList<Attribute>(3);
        attributes.add(length);
        attributes.add(weight);
        attributes.add(position);
        
        // Create the empty dataset "race" with above attributes
        Instances race = new Instances("race", attributes, 0);
        
        // Make position the class attribute
        race.setClassIndex(position.index());
        
        // Create empty instance with three attribute values
        SparseInstance inst = new SparseInstance(3);
        
        // Set instance's values for the attributes "length", "weight", and "position"
        inst.setValue(length, 5.3);
        inst.setValue(weight, 300);
        inst.setValue(position, "first");
        
        // Set instance's dataset to be the dataset "race"
        inst.setDataset(race);
        
        // Print the instance
        System.out.println("The instance: " + inst);
        
        // Print the first attribute
        System.out.println("First attribute: " + inst.attribute(0));
        
        // Print the class attribute
        System.out.println("Class attribute: " + inst.classAttribute());
        
        // Print the class index
        System.out.println("Class index: " + inst.classIndex());
        
        // Say if class is missing
        System.out.println("Class is missing: " + inst.classIsMissing());
        
        // Print the instance's class value in internal format
        System.out.println("Class value (internal format): " + inst.classValue());
        
        // Print a shallow copy of this instance
        SparseInstance copy = (SparseInstance) inst.copy();
        System.out.println("Shallow copy: " + copy);
        
        // Set dataset for shallow copy
        copy.setDataset(inst.dataset());
        System.out.println("Shallow copy with dataset set: " + copy);
  
        // Print out all values in internal format
        System.out.print("All stored values in internal format: ");
        for (int i = 0; i < inst.numValues(); i++) {
  	if (i > 0) {
  	  System.out.print(",");
  	}
  	System.out.print(inst.valueSparse(i));
        }
        System.out.println();
  
        // Set all values to zero
        System.out.print("All values set to zero: ");
        while (inst.numValues() > 0) {
  	inst.setValueSparse(0, 0);
        }
        for (int i = 0; i < inst.numValues(); i++) {
  	if (i > 0) {
  	  System.out.print(",");
  	}
  	System.out.print(inst.valueSparse(i));
        }
        System.out.println();
  
        // Set all values to one
        System.out.print("All values set to one: ");
        for (int i = 0; i < inst.numAttributes(); i++) {
  	inst.setValue(i, 1);
        }
        for (int i = 0; i < inst.numValues(); i++) {
  	if (i > 0) {
  	  System.out.print(",");
  	}
  	System.out.print(inst.valueSparse(i));
        }
        System.out.println();
  
        // Unset dataset for copy, delete first attribute, and insert it again
        copy.setDataset(null);
        copy.deleteAttributeAt(0);
        copy.insertAttributeAt(0);
        copy.setDataset(inst.dataset());
        System.out.println("Copy with first attribute deleted and inserted: " + copy); 
  
        // Same for second attribute
        copy.setDataset(null);
        copy.deleteAttributeAt(1);
        copy.insertAttributeAt(1);
        copy.setDataset(inst.dataset());
        System.out.println("Copy with second attribute deleted and inserted: " + copy); 
  
        // Same for last attribute
        copy.setDataset(null);
        copy.deleteAttributeAt(2);
        copy.insertAttributeAt(2);
        copy.setDataset(inst.dataset());
        System.out.println("Copy with third attribute deleted and inserted: " + copy); 
        
        // Enumerate attributes (leaving out the class attribute)
        System.out.println("Enumerating attributes (leaving out class):");
        Enumeration enu = inst.enumerateAttributes();
        while (enu.hasMoreElements()) {
  	Attribute att = (Attribute) enu.nextElement();
  	System.out.println(att);
        }
        
        // Headers are equivalent?
        System.out.println("Header of original and copy equivalent: " +
  			 inst.equalHeaders(copy));
  
        // Test for missing values
        System.out.println("Length of copy missing: " + copy.isMissing(length));
        System.out.println("Weight of copy missing: " + copy.isMissing(weight.index()));
        System.out.println("Length of copy missing: " + 
  			 Utils.isMissingValue(copy.value(length)));
  
        // Prints number of attributes and classes
        System.out.println("Number of attributes: " + copy.numAttributes());
        System.out.println("Number of classes: " + copy.numClasses());
  
        // Replace missing values
        double[] meansAndModes = {2, 3, 0};
        copy.replaceMissingValues(meansAndModes);
        System.out.println("Copy with missing value replaced: " + copy);
  
        // Setting and getting values and weights
        copy.setClassMissing();
        System.out.println("Copy with missing class: " + copy);
        copy.setClassValue(0);
        System.out.println("Copy with class value set to first value: " + copy);
        copy.setClassValue("third");
        System.out.println("Copy with class value set to \"third\": " + copy);
        copy.setMissing(1);
        System.out.println("Copy with second attribute set to be missing: " + copy);
        copy.setMissing(length);
        System.out.println("Copy with length set to be missing: " + copy);
        copy.setValue(0, 0);
        System.out.println("Copy with first attribute set to 0: " + copy);
        copy.setValue(weight, 1);
        System.out.println("Copy with weight attribute set to 1: " + copy);
        copy.setValue(position, "second");
        System.out.println("Copy with position set to \"second\": " + copy);
        copy.setValue(2, "first");
        System.out.println("Copy with last attribute set to \"first\": " + copy);
        System.out.println("Current weight of instance copy: " + copy.weight());
        copy.setWeight(2);
        System.out.println("Current weight of instance copy (set to 2): " + copy.weight());
        System.out.println("Last value of copy: " + copy.toString(2));
        System.out.println("Value of position for copy: " + copy.toString(position));
        System.out.println("Last value of copy (internal format): " + copy.value(2));
        System.out.println("Value of position for copy (internal format): " + 
  			 copy.value(position));
      } catch (Exception e) {
        e.printStackTrace();
      }
    }
    
    /**
     * Returns the revision string.
     * 
     * @return		the revision
     */
    public String getRevision() {
      return RevisionUtils.extract("$Revision: 5987 $");
    }
  }
  