source: src/main/java/weka/core/DenseInstance.java @ 6

/*
 *    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.
 */

/*
 *    DenseInstance.java
 *    Copyright (C) 1999 University of Waikato, Hamilton, New Zealand
 *
 */

package weka.core;

import java.io.Serializable;
import java.util.Enumeration;
import java.util.ArrayList;

/**
 * Class for handling an instance. All values (numeric, date, nominal, string
 * or relational) are internally stored as floating-point numbers. If an
 * attribute is nominal (or a string or relational), the stored value is the
 * index of the corresponding nominal (or string or relational) value in the
 * attribute's definition. We have chosen this approach in favor of a more
 * elegant object-oriented approach because it is much faster. <p>
 *
 * Typical usage (code from the main() method of this class): <p>
 *
 * <code>
 * ... <br>
 *      
 * // Create empty instance with three attribute values <br>
 * Instance inst = new DenseInstance(3); <br><br>
 *     
 * // Set instance's values for the attributes "length", "weight", and "position"<br>
 * inst.setValue(length, 5.3); <br>
 * inst.setValue(weight, 300); <br>
 * inst.setValue(position, "first"); <br><br>
 *   
 * // Set instance's dataset to be the dataset "race" <br>
 * inst.setDataset(race); <br><br>
 *   
 * // Print the instance <br>
 * System.out.println("The instance: " + inst); <br>
 *
 * ... <br>
 * </code><p>
 *
 * All methods that change an instance's attribute values are safe,
 * ie. a change of an instance's attribute values does not affect any
 * other instances. All methods that change an instance's attribute
 * values clone the attribute value vector before it is changed. If
 * your application heavily modifies instance values, it may be faster
 * to create a new instance from scratch.
 *
 * @author Eibe Frank (eibe@cs.waikato.ac.nz)
 * @version $Revision: 5987 $ 
 */
public class DenseInstance extends AbstractInstance {
  
  /** for serialization */
  static final long serialVersionUID = 1482635194499365122L;

  /**
   * Constructor that copies the attribute values and the weight from
   * the given instance. It does NOT perform a deep copy of the
   * attribute values if the instance provided is also of type
   * DenseInstance (it simply copies the reference to the array of
   * values), otherwise it does. 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 
   */
  //@ ensures m_Dataset == null;
  public DenseInstance(/*@non_null@*/ Instance instance) {
      
    if (instance instanceof DenseInstance) {
      m_AttValues = ((DenseInstance)instance).m_AttValues;
    } else {
      m_AttValues = instance.toDoubleArray();
    }
    m_Weight = instance.weight();
    m_Dataset = null;
  }

  /**
   * 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)
   *
   * @param weight the instance's weight
   * @param attValues a vector of attribute values 
   */
  //@ ensures m_Dataset == null;
  public DenseInstance(double weight,  /*@non_null@*/ double[]attValues){
    
    m_AttValues = attValues;
    m_Weight = weight;
    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 
   */
  //@ requires numAttributes > 0;    // Or maybe == 0 is okay too?
  //@ ensures m_Dataset == null;
  public DenseInstance(int numAttributes) {
    
    m_AttValues = new double[numAttributes];
    for (int i = 0; i < m_AttValues.length; i++) {
      m_AttValues[i] = Utils.missingValue();
    }
    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 DenseInstance(instance)</code>
   *
   * @return the shallow copy
   */
  //@ also ensures \result != null;
  //@ also ensures \result instanceof DenseInstance;
  //@ also ensures ((DenseInstance)\result).m_Dataset == m_Dataset;
  public /*@pure@*/ Object copy() {

    DenseInstance result = new DenseInstance(this);
    result.m_Dataset = m_Dataset;
    return result;
  }

  /**
   * Returns the index of the attribute stored at the given position.
   * Just returns the given value.
   *
   * @param position the position 
   * @return the index of the attribute stored at the given position
   */
  public /*@pure@*/ int index(int position) {

    return position;
  }

  /**
   * Merges this instance with the given instance and returns
   * the result. Dataset is set to null. The returned instance
   * is of the same type as this instance.
   *
   * @param inst the instance to be merged with this one
   * @return the merged instances
   */
  public Instance mergeInstance(Instance inst) {

    int m = 0;
    double [] newVals = new double[numAttributes() + inst.numAttributes()];
    for (int j = 0; j < numAttributes(); j++, m++) {
      newVals[m] = value(j);
    }
    for (int j = 0; j < inst.numAttributes(); j++, m++) {
      newVals[m] = inst.value(j);
    }
    return new DenseInstance(1.0, newVals);
  }

  /**
   * Returns the number of attributes.
   *
   * @return the number of attributes as an integer
   */
  //@ ensures \result == m_AttValues.length;
  public /*@pure@*/ int numAttributes() {

    return m_AttValues.length;
  }

  /**
   * Returns the number of values present. Always the same as numAttributes().
   *
   * @return the number of values
   */
  //@ ensures \result == m_AttValues.length;
  public /*@pure@*/ int numValues() {

    return m_AttValues.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
   * @throws IllegalArgumentException if numbers of attributes are unequal
   */
  public void replaceMissingValues(double[] array) {
         
    if ((array == null) || 
        (array.length != m_AttValues.length)) {
      throw new IllegalArgumentException("Unequal number of attributes!");
    }
    freshAttributeVector();
    for (int i = 0; i < m_AttValues.length; i++) {
      if (isMissing(i)) {
        m_AttValues[i] = array[i];
      }
    }
  }

  /**
   * 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) {
    
    freshAttributeVector();
    m_AttValues[attIndex] = value;
  }

  /**
   * 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.
   * Does exactly the same thing as setValue().
   *
   * @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) {
    
    freshAttributeVector();
    m_AttValues[indexOfIndex] = value;
  }

  /**
   * 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_AttValues.length];
    System.arraycopy(m_AttValues, 0, newValues, 0, 
                     m_AttValues.length);
    return newValues;
  }

  /**
   * Returns the description of one instance (without weight
   * appended). If the instance
   * doesn't have access to a dataset, it returns the internal
   * floating-point values. Quotes string
   * values that contain whitespace characters.
   *
   * This method is used by getRandomNumberGenerator() in
   * Instances.java in order to maintain backwards compatibility
   * with weka 3.4.
   *
   * @return the instance's description as a string
   */
  public String toStringNoWeight() {
    StringBuffer text = new StringBuffer();
    
    for (int i = 0; i < m_AttValues.length; i++) {
      if (i > 0) text.append(",");
      text.append(toString(i));
    }

    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 /*@pure@*/ double value(int attIndex) {

    return m_AttValues[attIndex];
  }

  /**
   * Deletes an attribute at the given position (0 to 
   * numAttributes() - 1).
   *
   * @param position the attribute's position
   */
  protected void forceDeleteAttributeAt(int position) {

    double[] newValues = new double[m_AttValues.length - 1];

    System.arraycopy(m_AttValues, 0, newValues, 0, position);
    if (position < m_AttValues.length - 1) {
      System.arraycopy(m_AttValues, position + 1, 
                       newValues, position, 
                       m_AttValues.length - (position + 1));
    }
    m_AttValues = newValues;
  }

  /**
   * Inserts an attribute at the given position
   * (0 to numAttributes()) and sets its value to be missing. 
   *
   * @param position the attribute's position
   */
  protected void forceInsertAttributeAt(int position)  {

    double[] newValues = new double[m_AttValues.length + 1];

    System.arraycopy(m_AttValues, 0, newValues, 0, position);
    newValues[position] = Utils.missingValue();
    System.arraycopy(m_AttValues, position, newValues, 
                     position + 1, m_AttValues.length - position);
    m_AttValues = newValues;
  }

  /**
   * Clones the attribute vector of the instance and
   * overwrites it with the clone.
   */
  private void freshAttributeVector() {

    m_AttValues = toDoubleArray();
  }

  /**
   * Main method for testing this class.
   * 
   * @param options the commandline options - ignored
   */
  //@ requires options != null;
  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
      Instance inst = new DenseInstance(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
      Instance copy = (Instance) 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);
      
      // 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); 
      
      // 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 $");
  }
}