public void train(DataSet ds) {
initializeExampleWeights(ds.examples.Count);
foreach (Learner learner in learners) {
learner.train(ds);
double error = calculateError(ds, learner);
if (error < 0.0001) {
break;
}
adjustExampleWeights(ds, learner, error);
double newHypothesisWeight = learnerWeights[learner]
* Math.Log((1.0 - error) / error);
if (learnerWeights.ContainsKey(learner))
{
learnerWeights[learner] = newHypothesisWeight;
}
else
{
learnerWeights.Add(learner, newHypothesisWeight);
}
}
}
//
// PRIVATE METHODS
//
private DecisionTree decisionTreeLearning(DataSet ds,
List<String> attributeNames, ConstantDecisonTree defaultTree)
{
if (ds.size() == 0)
{
return defaultTree;
}
if (allExamplesHaveSameClassification(ds))
{
return new ConstantDecisonTree(ds.getExample(0).targetValue());
}
if (attributeNames.Count == 0)
{
return majorityValue(ds);
}
String chosenAttribute = chooseAttribute(ds, attributeNames);
DecisionTree tree = new DecisionTree(chosenAttribute);
ConstantDecisonTree m = majorityValue(ds);
List<String> values = ds.getPossibleAttributeValues(chosenAttribute);
foreach (String v in values)
{
DataSet filtered = ds.matchingDataSet(chosenAttribute, v);
List<String> newAttribs = Util.removeFrom(attributeNames,
chosenAttribute);
DecisionTree subTree = decisionTreeLearning(filtered, newAttribs, m);
tree.addNode(v, subTree);
}
return tree;
}
/*
* create a normalized data "table" from the DataSet using numerizer. At
* this stage, the data isnot split into input pattern and targets TODO
* remove redundancy of recreating the target columns. the numerizer has
* already isolated the targets
*/
public void createNormalizedDataFromDataSet(DataSet ds, Numerizer numerizer)
{
List<List<Double>> rds = rawExamplesFromDataSet(ds, numerizer);
// normalize raw dataset
nds = normalize(rds);
}
public AdaBoostLearner(List<Learner> learners, DataSet ds)
{
this.learners = learners;
this.dataSet = ds;
initializeExampleWeights(ds.examples.Count);
initializeHypothesisWeights(learners.Count);
}
public void train(DataSet ds)
{
List<String> targets = new List<String>();
foreach (Example e in ds.examples)
{
targets.Add(e.targetValue());
}
result = Util.mode(targets);
}
public DataSet unmatchedExamples(DataSet ds)
{
DataSet unmatched = ds.emptyDataSet();
foreach (Example e in ds.examples)
{
if (!(matches(e)))
{
unmatched.add(e);
}
}
return unmatched;
}
public DataSet removeExample(Example e)
{
DataSet ds = new DataSet(specification);
foreach (Example eg in examples)
{
if (!(e.Equals(eg)))
{
ds.add(eg);
}
}
return ds;
}
public static DecisionTree getStumpFor(DataSet ds, String attributeName,
String attributeValue, String returnValueIfMatched,
List<String> unmatchedValues, String returnValueIfUnmatched)
{
DecisionTree dt = new DecisionTree(attributeName);
dt.addLeaf(attributeValue, returnValueIfMatched);
foreach (String unmatchedValue in unmatchedValues)
{
dt.addLeaf(unmatchedValue, returnValueIfUnmatched);
}
return dt;
}
public int[] test(DataSet ds) {
int[] results = new int[] { 0, 0 };
foreach (Example e in ds.examples) {
if (e.targetValue().Equals(predict(e))) {
results[0] = results[0] + 1;
} else {
results[1] = results[1] + 1;
}
}
return results;
}
public DataSet fromFile(String filename, DataSetSpecification spec,
Char separator) {
// assumed file in data directory and ends in .csv
DataSet ds = new DataSet(spec);
using (StreamReader reader = new StreamReader(typeof(DataSetFactory).Assembly.GetManifestResourceStream("AIMA.Resource." + filename)))
{
String line;
while ((line = reader.ReadLine()) != null)
{
ds.add(exampleFromString(line, spec, separator));
}
}
return ds;
}
//
// START-Learner
public void train(DataSet ds) {
folDSDomain = new FOLDataSetDomain(ds.specification, trueGoalValue);
List<FOLExample> folExamples = new List<FOLExample>();
int egNo = 1;
foreach (Example e in ds.examples) {
folExamples.Add(new FOLExample(folDSDomain, e, egNo));
egNo++;
}
// Setup a KB to be used for learning
kb = new FOLKnowledgeBase(folDSDomain, new FOLOTTERLikeTheoremProver(
1000, false));
CurrentBestLearning cbl = new CurrentBestLearning(folDSDomain, kb);
currentBestHypothesis = cbl.currentBestLearning(folExamples);
}
//
// PRIVATE METHODS
//
private DecisionList decisionListLearning(DataSet ds)
{
if (ds.size() == 0)
{
return new DecisionList(positive, negative);
}
List<DLTest> possibleTests = testFactory
.createDLTestsWithAttributeCount(ds, 1);
DLTest test = getValidTest(possibleTests, ds);
if (test == null)
{
return new DecisionList(null, FAILURE);
}
// at this point there is a test that classifies some subset of examples
// with the same target value
DataSet matched = test.matchedExamples(ds);
DecisionList list = new DecisionList(positive, negative);
list.add(test, matched.getExample(0).targetValue());
return list.mergeWith(decisionListLearning(test.unmatchedExamples(ds)));
}
public static List<DecisionTree> getStumpsFor(DataSet ds,
String returnValueIfMatched, String returnValueIfUnmatched)
{
List<String> attributes = ds.getNonTargetAttributes();
List<DecisionTree> trees = new List<DecisionTree>();
foreach (String attribute in attributes)
{
List<String> values = ds.getPossibleAttributeValues(attribute);
foreach (String value in values)
{
List<String> unmatchedValues = Util.removeFrom(ds
.getPossibleAttributeValues(attribute), value);
DecisionTree tree = getStumpFor(ds, attribute, value,
returnValueIfMatched, unmatchedValues,
returnValueIfUnmatched);
trees.Add(tree);
}
}
return trees;
}
public virtual void train(DataSet ds)
{
List<String> attributes = ds.getNonTargetAttributes();
this.tree = decisionTreeLearning(ds, attributes,
new ConstantDecisonTree(defaultValue));
}
/*
* method called by clients to set up data set and make it ready for
* processing
*/
public void createExamplesFromDataSet(DataSet ds, Numerizer numerizer)
{
createNormalizedDataFromDataSet(ds, numerizer);
setTargetColumns();
createExamples();
}
public DataSet matchingDataSet(String attributeName, String attributeValue)
{
DataSet ds = new DataSet(specification);
foreach (Example e in examples)
{
if (e.getAttributeValueAsString(attributeName).Equals(
attributeValue))
{
ds.add(e);
}
}
return ds;
}
public void testOn(DataSet ds) {
// TODO Auto-generated method stub
}
public Dictionary<String, DataSet> splitByAttribute(String attributeName)
{
Dictionary<String, DataSet> results = new Dictionary<String, DataSet>();
foreach (Example e in examples)
{
String val = e.getAttributeValueAsString(attributeName);
if (results.ContainsKey(val))
{
results[val].add(e);
}
else
{
DataSet ds = new DataSet(specification);
ds.add(e);
results.Add(val, ds);
}
}
return results;
}
public override void train(DataSet ds) {
// System.Console.WriteLine("Stump learner training");
// do nothing the stump is not inferred from the dataset
}
private DLTest getValidTest(List<DLTest> possibleTests, DataSet ds) {
foreach (DLTest test in possibleTests) {
DataSet matched = test.matchedExamples(ds);
if (!(matched.size() == 0)) {
if (allExamplesHaveSameTargetValue(matched)) {
return test;
}
}
}
return null;
}
private void adjustExampleWeights(DataSet ds, Learner l, double error)
{
double epsilon = error / (1.0 - error);
for (int j = 0; j < ds.examples.Count; j++)
{
Example e = ds.getExample(j);
if ((l.predict(e).Equals(e.targetValue())))
{
exampleWeights[j] = exampleWeights[j] * epsilon;
}
}
exampleWeights = Util.normalize(exampleWeights);
}
private double calculateError(DataSet ds, Learner l)
{
double error = 0.0;
for (int i = 0; i < ds.examples.Count; i++)
{
Example e = ds.getExample(i);
if (!(l.predict(e).Equals(e.targetValue())))
{
error = error + exampleWeights[i];
}
}
return error;
}
public void train(DataSet ds)
{
this.decisionList = decisionListLearning(ds);
}
private String chooseAttribute(DataSet ds, List<String> attributeNames)
{
double greatestGain = 0.0;
String attributeWithGreatestGain = attributeNames[0];
foreach (String attr in attributeNames)
{
double gain = ds.calculateGainFor(attr);
if (gain > greatestGain)
{
greatestGain = gain;
attributeWithGreatestGain = attr;
}
}
return attributeWithGreatestGain;
}
public DataSet copy()
{
DataSet ds = new DataSet(specification);
foreach (Example e in examples)
{
ds.add(e);
}
return ds;
}
private bool allExamplesHaveSameClassification(DataSet ds)
{
String classification = ds.getExample(0).targetValue();
List<Example>.Enumerator iter = ds.iterator();
while (iter.MoveNext())
{
Example element = iter.Current;
if (!(element.targetValue().Equals(classification)))
{
return false;
}
}
return true;
}
public override List<DLTest> createDLTestsWithAttributeCount(DataSet ds, int i)
{
return tests;
}
private List<List<Double>> rawExamplesFromDataSet(DataSet ds,
Numerizer numerizer) {
// assumes all values for inout and target are doubles
List<List<Double>> rds = new List<List<Double>>();
for (int i = 0; i < ds.size(); i++) {
List<Double> rexample = new List<Double>();
Example e = ds.getExample(i);
Pair<List<Double>, List<Double>> p = numerizer.numerize(e);
List<Double> attributes = p.getFirst();
foreach (Double d in attributes) {
rexample.Add(d);
}
List<Double> targets = p.getSecond();
foreach (Double d in targets) {
rexample.Add(d);
}
rds.Add(rexample);
}
return rds;
}
private ConstantDecisonTree majorityValue(DataSet ds)
{
Learner learner = new MajorityLearner();
learner.train(ds);
return new ConstantDecisonTree(learner.predict(ds.getExample(0)));
}
private bool allExamplesHaveSameTargetValue(DataSet matched) {
// assumes at least i example in dataset
String targetValue = matched.getExample(0).targetValue();
foreach (Example e in matched.examples) {
if (!(e.targetValue().Equals(targetValue))) {
return false;
}
}
return true;
}
