instance.java

wekaUT是 university texas austin 开发的基于weka的半指导学习(semi supervised learning)的分类器

   * @exception UnassignedDatasetException if the instance doesn't belong
   * to a dataset.
   */
  public final String stringValue(int attIndex) {

    if (m_Dataset == null) {
      throw new UnassignedDatasetException("Instance doesn't have access to a dataset!");
    } 
    return stringValue(m_Dataset.attribute(attIndex));
  }

  /** 
   * Returns the string value of a nominal, string, or date attribute
   * for the instance.
   *
   * @param att the attribute
   * @return the value as a string
   * @exception IllegalArgumentException if the attribute is not a nominal,
   * string, or date attribute.
   * @exception UnassignedDatasetException if the instance doesn't belong
   * to a dataset.
   */
  public final String stringValue(Attribute att) {

    int attIndex = att.index();
    switch (att.type()) {
    case Attribute.NOMINAL:
    case Attribute.STRING:
      return att.value((int) value(attIndex));
    case Attribute.DATE:
      return att.formatDate(value(attIndex));
    default:
      throw new IllegalArgumentException("Attribute isn't nominal, string or date!");
    }
  }

  /**
   * 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. 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 toString() {

    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 the description of one value of the instance as a 
   * string. If the instance doesn't have access to a dataset, it 
   * returns the internal floating-point value. Quotes string
   * values that contain whitespace characters, or if they
   * are a question mark.
   *
   * @param attIndex the attribute's index
   * @return the value's description as a string
   */
  public final String toString(int attIndex) {

   StringBuffer text = new StringBuffer();
   
   if (isMissing(attIndex)) {
     text.append("?");
   } else {
     if (m_Dataset == null) {
       text.append(Utils.doubleToString(m_AttValues[attIndex],6));
     } else {
       switch (m_Dataset.attribute(attIndex).type()) {
       case Attribute.NOMINAL:
       case Attribute.STRING:
       case Attribute.DATE:
         text.append(Utils.quote(stringValue(attIndex)));
         break;
       case Attribute.NUMERIC:
	 text.append(Utils.doubleToString(value(attIndex),6));
         break;
       default:
         throw new IllegalStateException("Unknown attribute type");
       }
     }
   }
   return text.toString();
  }

  /**
   * Returns the description of one value of the instance as a 
   * string. If the instance doesn't have access to a dataset it 
   * returns the internal floating-point value. Quotes string
   * values that contain whitespace characters, or if they
   * are a question mark.
   * The given attribute has to belong to a dataset.
   *
   * @param att the attribute
   * @return the value's description as a string
   */
  public final String toString(Attribute att) {
   
   return toString(att.index());
  }

  /**
   * 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) {

    return m_AttValues[attIndex];
  }

  /**
   * Returns an instance's attribute value in internal format.
   * Does exactly the same thing as value() if applied to an Instance.
   *
   * @param indexOfIndex the index of 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 valueSparse(int indexOfIndex) {

    return m_AttValues[indexOfIndex];
  }  

  /**
   * Returns an instance's attribute value in internal format.
   * The given attribute has to belong to a dataset.
   *
   * @param att the attribute
   * @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(Attribute att) {

    return value(att.index());
  }

  /**
   * Returns the instance's weight.
   *
   * @return the instance's weight as a double
   */
  public final double weight() {

    return m_Weight;
  }

  /**
   * Deletes an attribute at the given position (0 to 
   * numAttributes() - 1).
   *
   * @param pos the attribute's position
   */

  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 pos the attribute's position
   */
  void forceInsertAttributeAt(int position)  {

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

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

  /**
   * Private constructor for subclasses. Does nothing.
   */
  protected Instance() {
  }

  /**
   * 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.
   */
  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" 
      FastVector my_nominal_values = new FastVector(3); 
      my_nominal_values.addElement("first"); 
      my_nominal_values.addElement("second"); 
      my_nominal_values.addElement("third"); 
      
      // Create nominal attribute "position" 
      Attribute position = new Attribute("position", my_nominal_values);
      
      // Create vector of the above attributes 
      FastVector attributes = new FastVector(3);
      attributes.addElement(length);
      attributes.addElement(weight);
      attributes.addElement(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 Instance(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 enum = inst.enumerateAttributes();
      while (enum.hasMoreElements()) {
	Attribute att = (Attribute) enum.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: " + 
			 Instance.isMissingValue(copy.value(length)));
      System.out.println("Missing value coded as: " + Instance.missingValue());

      // 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();
    }
  }
}