Java tutorial
/* * 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 3 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, see <http://www.gnu.org/licenses/>. */ /* * DenseInstance.java * Copyright (C) 1999-2012 University of Waikato, Hamilton, New Zealand * */ package weka.core; import java.util.ArrayList; import java.util.Enumeration; /** * 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 $Revision$ */ 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; @Override public/* @pure@ */Object copy() { DenseInstance result = new DenseInstance(this); result.m_Dataset = m_Dataset; return result; } /** * Copies the instance but fills up its values based on the given array * of doubles. The copy has access to the same dataset. * * @param values the array with new values * @return the new instance */ public Instance copy(double[] values) { DenseInstance result = new DenseInstance(this.m_Weight, values); 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 */ @Override 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 */ @Override 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; @Override 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; @Override 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 */ @Override 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). */ @Override 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). */ @Override public void setValueSparse(int indexOfIndex, double value) { freshAttributeVector(); m_AttValues[indexOfIndex] = value; } /** * Returns the values of each attribute as an array of doubles. Creates a fresh array object for this. * * @return an array containing all the instance attribute values */ @Override 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 */ @Override public String toStringNoWeight() { return toStringNoWeight(AbstractInstance.s_numericAfterDecimalPoint); } /** * 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. * * @param afterDecimalPoint maximum number of digits after the decimal point * for numeric values * * @return the instance's description as a string */ @Override public String toStringNoWeight(int afterDecimalPoint) { StringBuffer text = new StringBuffer(); for (int i = 0; i < m_AttValues.length; i++) { if (i > 0) { text.append(","); } text.append(toString(i, afterDecimalPoint)); } 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). */ @Override 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 */ @Override 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 */ @Override 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<Attribute> enu = inst.enumerateAttributes(); while (enu.hasMoreElements()) { Attribute att = 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 */ @Override public String getRevision() { return RevisionUtils.extract("$Revision$"); } }