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The Waikato Environment for Knowledge Analysis (WEKA), a machine
learning workbench. This version represents the developer version, the
"bleeding edge" of development, you could say. New functionality gets added
to this version.
/*
* 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 .
*/
/*
* BayesNet.java
* Copyright (C) 2001-2012 University of Waikato, Hamilton, New Zealand
*
*/
package weka.classifiers.bayes;
import java.util.Collections;
import java.util.Enumeration;
import java.util.Vector;
import weka.classifiers.AbstractClassifier;
import weka.classifiers.bayes.net.ADNode;
import weka.classifiers.bayes.net.BIFReader;
import weka.classifiers.bayes.net.ParentSet;
import weka.classifiers.bayes.net.estimate.BayesNetEstimator;
import weka.classifiers.bayes.net.estimate.DiscreteEstimatorBayes;
import weka.classifiers.bayes.net.estimate.SimpleEstimator;
import weka.classifiers.bayes.net.search.SearchAlgorithm;
import weka.classifiers.bayes.net.search.local.K2;
import weka.classifiers.bayes.net.search.local.LocalScoreSearchAlgorithm;
import weka.classifiers.bayes.net.search.local.Scoreable;
import weka.core.AdditionalMeasureProducer;
import weka.core.Attribute;
import weka.core.Capabilities;
import weka.core.Capabilities.Capability;
import weka.core.Drawable;
import weka.core.Instance;
import weka.core.Instances;
import weka.core.Option;
import weka.core.OptionHandler;
import weka.core.RevisionUtils;
import weka.core.Utils;
import weka.core.WeightedInstancesHandler;
import weka.estimators.Estimator;
import weka.filters.Filter;
import weka.filters.supervised.attribute.Discretize;
import weka.filters.unsupervised.attribute.ReplaceMissingValues;
/**
* Bayes Network learning using various search
* algorithms and quality measures.
* Base class for a Bayes Network classifier. Provides datastructures (network
* structure, conditional probability distributions, etc.) and facilities common
* to Bayes Network learning algorithms like K2 and B.
*
* For more information see:
*
* http://sourceforge.net/projects/weka/files/documentation/WekaManual-3-7-0.pdf
* /download
*
*
*
* Valid options are:
*
*
*
*
*
*
* @author Remco Bouckaert ([email protected])
* @version $Revision: 11325 $
*/
public class BayesNet extends AbstractClassifier implements OptionHandler,
WeightedInstancesHandler, Drawable, AdditionalMeasureProducer {
/** for serialization */
static final long serialVersionUID = 746037443258775954L;
/**
* The parent sets.
*/
protected ParentSet[] m_ParentSets;
/**
* The attribute estimators containing CPTs.
*/
public Estimator[][] m_Distributions;
/** filter used to quantize continuous variables, if any **/
protected Discretize m_DiscretizeFilter = null;
/** attribute index of a non-nominal attribute */
int m_nNonDiscreteAttribute = -1;
/** filter used to fill in missing values, if any **/
protected ReplaceMissingValues m_MissingValuesFilter = null;
/**
* The number of classes
*/
protected int m_NumClasses;
/**
* The dataset header for the purposes of printing out a semi-intelligible
* model
*/
public Instances m_Instances;
/**
* The number of instances the model was built from
*/
private int m_NumInstances;
/**
* Datastructure containing ADTree representation of the database. This may
* result in more efficient access to the data.
*/
ADNode m_ADTree;
/**
* Bayes network to compare the structure with.
*/
protected BIFReader m_otherBayesNet = null;
/**
* Use the experimental ADTree datastructure for calculating contingency
* tables
*/
boolean m_bUseADTree = false;
/**
* Search algorithm used for learning the structure of a network.
*/
SearchAlgorithm m_SearchAlgorithm = new K2();
/**
* Search algorithm used for learning the structure of a network.
*/
BayesNetEstimator m_BayesNetEstimator = new SimpleEstimator();
/**
* Returns default capabilities of the classifier.
*
* @return the capabilities of this classifier
*/
@Override
public Capabilities getCapabilities() {
Capabilities result = super.getCapabilities();
result.disableAll();
// attributes
result.enable(Capability.NOMINAL_ATTRIBUTES);
result.enable(Capability.NUMERIC_ATTRIBUTES);
result.enable(Capability.MISSING_VALUES);
// class
result.enable(Capability.NOMINAL_CLASS);
result.enable(Capability.MISSING_CLASS_VALUES);
// instances
result.setMinimumNumberInstances(0);
return result;
}
/**
* Generates the classifier.
*
* @param instances set of instances serving as training data
* @throws Exception if the classifier has not been generated successfully
*/
@Override
public void buildClassifier(Instances instances) throws Exception {
// can classifier handle the data?
getCapabilities().testWithFail(instances);
// remove instances with missing class
instances = new Instances(instances);
instances.deleteWithMissingClass();
// ensure we have a data set with discrete variables only and with no
// missing values
instances = normalizeDataSet(instances);
// Copy the instances
m_Instances = new Instances(instances);
m_NumInstances = m_Instances.numInstances();
// sanity check: need more than 1 variable in datat set
m_NumClasses = instances.numClasses();
// initialize ADTree
if (m_bUseADTree) {
m_ADTree = ADNode.makeADTree(instances);
// System.out.println("Oef, done!");
}
// build the network structure
initStructure();
// build the network structure
buildStructure();
// build the set of CPTs
estimateCPTs();
// Save space
m_Instances = new Instances(m_Instances, 0);
m_ADTree = null;
} // buildClassifier
/**
* Returns the number of instances the model was built from.
*/
public int getNumInstances() {
return m_NumInstances;
}
/**
* ensure that all variables are nominal and that there are no missing values
*
* @param instances data set to check and quantize and/or fill in missing
* values
* @return filtered instances
* @throws Exception if a filter (Discretize, ReplaceMissingValues) fails
*/
protected Instances normalizeDataSet(Instances instances) throws Exception {
m_nNonDiscreteAttribute = -1;
Enumeration enu = instances.enumerateAttributes();
while (enu.hasMoreElements()) {
Attribute attribute = enu.nextElement();
if (attribute.type() != Attribute.NOMINAL) {
m_nNonDiscreteAttribute = attribute.index();
}
}
if ((m_nNonDiscreteAttribute > -1)
&& (instances.attribute(m_nNonDiscreteAttribute).type() != Attribute.NOMINAL)) {
m_DiscretizeFilter = new Discretize();
m_DiscretizeFilter.setInputFormat(instances);
instances = Filter.useFilter(instances, m_DiscretizeFilter);
}
m_MissingValuesFilter = new ReplaceMissingValues();
m_MissingValuesFilter.setInputFormat(instances);
instances = Filter.useFilter(instances, m_MissingValuesFilter);
return instances;
} // normalizeDataSet
/**
* ensure that all variables are nominal and that there are no missing values
*
* @param instance instance to check and quantize and/or fill in missing
* values
* @return filtered instance
* @throws Exception if a filter (Discretize, ReplaceMissingValues) fails
*/
protected Instance normalizeInstance(Instance instance) throws Exception {
if ((m_nNonDiscreteAttribute > -1)
&& (instance.attribute(m_nNonDiscreteAttribute).type() != Attribute.NOMINAL)) {
m_DiscretizeFilter.input(instance);
instance = m_DiscretizeFilter.output();
}
m_MissingValuesFilter.input(instance);
instance = m_MissingValuesFilter.output();
return instance;
} // normalizeInstance
/**
* Init structure initializes the structure to an empty graph or a Naive Bayes
* graph (depending on the -N flag).
*
* @throws Exception in case of an error
*/
public void initStructure() throws Exception {
// initialize topological ordering
// m_nOrder = new int[m_Instances.numAttributes()];
// m_nOrder[0] = m_Instances.classIndex();
int nAttribute = 0;
for (int iOrder = 1; iOrder < m_Instances.numAttributes(); iOrder++) {
if (nAttribute == m_Instances.classIndex()) {
nAttribute++;
}
// m_nOrder[iOrder] = nAttribute++;
}
// reserve memory
m_ParentSets = new ParentSet[m_Instances.numAttributes()];
for (int iAttribute = 0; iAttribute < m_Instances.numAttributes(); iAttribute++) {
m_ParentSets[iAttribute] = new ParentSet(m_Instances.numAttributes());
}
} // initStructure
/**
* buildStructure determines the network structure/graph of the network. The
* default behavior is creating a network where all nodes have the first node
* as its parent (i.e., a BayesNet that behaves like a naive Bayes
* classifier). This method can be overridden by derived classes to restrict
* the class of network structures that are acceptable.
*
* @throws Exception in case of an error
*/
public void buildStructure() throws Exception {
m_SearchAlgorithm.buildStructure(this, m_Instances);
} // buildStructure
/**
* estimateCPTs estimates the conditional probability tables for the Bayes Net
* using the network structure.
*
* @throws Exception in case of an error
*/
public void estimateCPTs() throws Exception {
m_BayesNetEstimator.estimateCPTs(this);
} // estimateCPTs
/**
* initializes the conditional probabilities
*
* @throws Exception in case of an error
*/
public void initCPTs() throws Exception {
m_BayesNetEstimator.initCPTs(this);
} // estimateCPTs
/**
* Updates the classifier with the given instance.
*
* @param instance the new training instance to include in the model
* @throws Exception if the instance could not be incorporated in the model.
*/
public void updateClassifier(Instance instance) throws Exception {
instance = normalizeInstance(instance);
m_BayesNetEstimator.updateClassifier(this, instance);
} // updateClassifier
/**
* Calculates the class membership probabilities for the given test instance.
*
* @param instance the instance to be classified
* @return predicted class probability distribution
* @throws Exception if there is a problem generating the prediction
*/
@Override
public double[] distributionForInstance(Instance instance) throws Exception {
instance = normalizeInstance(instance);
return m_BayesNetEstimator.distributionForInstance(this, instance);
} // distributionForInstance
/**
* Calculates the counts for Dirichlet distribution for the class membership
* probabilities for the given test instance.
*
* @param instance the instance to be classified
* @return counts for Dirichlet distribution for class probability
* @throws Exception if there is a problem generating the prediction
*/
public double[] countsForInstance(Instance instance) throws Exception {
double[] fCounts = new double[m_NumClasses];
for (int iClass = 0; iClass < m_NumClasses; iClass++) {
fCounts[iClass] = 0.0;
}
for (int iClass = 0; iClass < m_NumClasses; iClass++) {
double fCount = 0;
for (int iAttribute = 0; iAttribute < m_Instances.numAttributes(); iAttribute++) {
double iCPT = 0;
for (int iParent = 0; iParent < m_ParentSets[iAttribute]
.getNrOfParents(); iParent++) {
int nParent = m_ParentSets[iAttribute].getParent(iParent);
if (nParent == m_Instances.classIndex()) {
iCPT = iCPT * m_NumClasses + iClass;
} else {
iCPT = iCPT * m_Instances.attribute(nParent).numValues()
+ instance.value(nParent);
}
}
if (iAttribute == m_Instances.classIndex()) {
fCount += ((DiscreteEstimatorBayes) m_Distributions[iAttribute][(int) iCPT])
.getCount(iClass);
} else {
fCount += ((DiscreteEstimatorBayes) m_Distributions[iAttribute][(int) iCPT])
.getCount(instance.value(iAttribute));
}
}
fCounts[iClass] += fCount;
}
return fCounts;
} // countsForInstance
/**
* Returns an enumeration describing the available options
*
* @return an enumeration of all the available options
*/
@Override
public Enumeration