public TrainingExample[] OverSample(TrainingExample[] trainingExamples, SamplingParams samplingParams)
{
if (!samplingParams.NeedSampling)
return trainingExamples;
var trainingSet = new TrainingSet(trainingExamples);
var delta = Math.Min(trainingSet.Majority.Length - trainingSet.Minority.Length, trainingSet.Minority.Length * samplingParams.MinorityClassMaxOversampling);
var additionalSamples = Enumerable.Range(0, delta).Select(x => OverSample(trainingSet, samplingParams)).ToArray();
return trainingExamples.Concat(additionalSamples).RandomShuffle().ToArray();
}
public static ClassificationAlgorithmBuildResult Create(IClassificationAlgorithm classificationAlgorithm, TrainingExample[] trainingSet)
{
var errorsCount = trainingSet.Count(x => classificationAlgorithm.Classify(x.Features).PredictedClass != x.ExpectedResult);
var error = errorsCount * 1.0 / trainingSet.Length;
return new ClassificationAlgorithmBuildResult
{
ClassificationAlgorithm = classificationAlgorithm,
Error = error
};
}
public ClassificationAlgorithmBuildResult Build(TrainingExample[] trainingSet, ClassificationAlgorithmParams classificationAlgorithmParams)
{
totalExamples = trainingSet.Length;
outputClassesCount = trainingSet.Max(x => x.ExpectedResult) + 1;
featuresCount = trainingSet[0].Features.Length;
featuresClassesCount = trainingSet.SelectMany(x => x.Features.Values).Max() + 1;
classProb = new double[outputClassesCount];
classCounts = new int[outputClassesCount];
featureWithValueProb = new double[featuresCount, featuresClassesCount];
featureWithValueWithinClassProb = new double[featuresCount, featuresClassesCount, outputClassesCount];
foreach (var trainingExample in trainingSet)
{
classCounts[trainingExample.ExpectedResult]++;
}
foreach (var trainingExample in trainingSet)
{
var features = trainingExample.Features;
var classNumber = trainingExample.ExpectedResult;
for (var featureNumber = 0; featureNumber < featuresCount; featureNumber++)
{
featureWithValueProb[featureNumber, features[featureNumber]]++;
featureWithValueWithinClassProb[featureNumber, features[featureNumber], classNumber]++;
}
}
for (var classNumber = 0; classNumber < outputClassesCount; classNumber++)
{
classProb[classNumber] = classCounts[classNumber] * 1.0 / trainingSet.Length;
}
for (var featureNumber = 0; featureNumber < featuresCount; featureNumber++)
{
for (var featureValue = 0; featureValue < featuresClassesCount; featureValue++)
{
featureWithValueProb[featureNumber, featureValue] = Normalize(featureWithValueProb[featureNumber, featureValue], totalExamples);
for (var classNumber = 0; classNumber < outputClassesCount; classNumber++)
{
featureWithValueWithinClassProb[featureNumber, featureValue, classNumber] =
Normalize(featureWithValueWithinClassProb[featureNumber, featureValue, classNumber], classCounts[classNumber]);
}
}
}
var result = new NaiveBayesAlgorithm(classProb, featureWithValueProb, featureWithValueWithinClassProb, classCounts, totalExamples,
outputClassesCount, featuresCount, featuresClassesCount);
return ClassificationAlgorithmBuildResult.Create(result, trainingSet);
}
public ClassificationAlgorithmBuildResult Build(TrainingExample[] trainingSet, ClassificationAlgorithmParams classificationAlgorithmParams)
{
var featuresDimensionality = trainingSet[0].Features.Length;
var outputClassesCount = trainingSet.Max(x => x.ExpectedResult) + 1;
var inputs = trainingSet.Select(example => example.Features.ToDoubleArray()).ToArray();
var outputs = trainingSet.Select(example => example.ExpectedResult).ToArray();
var classifier = new MulticlassSupportVectorMachine(featuresDimensionality, new Linear(), outputClassesCount);
var teacher = new MulticlassSupportVectorLearning(classifier, inputs, outputs)
{
Algorithm = (svm, classInputs, classOutputs, i, j) =>
new SequentialMinimalOptimization(svm, classInputs, classOutputs)
};
teacher.Run();
var result = new SupportVectorMachineAlgorithm(classifier);
return ClassificationAlgorithmBuildResult.Create(result, trainingSet);
}
public TrainingSet(TrainingExample[] trainingSet)
{
Total = trainingSet.Length;
Minority = trainingSet.Where(x => x.ExpectedResult == 1).ToArray();
Majority = trainingSet.Where(x => x.ExpectedResult == 0).ToArray();
if (Minority.Length > Majority.Length)
{
TrainingExample[] buf = Minority;
Minority = Majority;
Majority = buf;
}
MajorityFeatureFreq = new int[trainingSet[0].Features.Length];
MinorityFeatureFreq = new int[trainingSet[0].Features.Length];
for (var featureNumber = 0; featureNumber < trainingSet[0].Features.Length; featureNumber++)
{
MajorityFeatureFreq[featureNumber] = Majority.Count(x => x.Features[featureNumber] == 1);
MinorityFeatureFreq[featureNumber] = Minority.Count(x => x.Features[featureNumber] == 1);
}
}
public ClassificationAlgorithmBuildResult Build(TrainingExample[] trainingSet, ClassificationAlgorithmParams classificationAlgorithmParams)
{
var builder = builders.First(x => x.Type == classificationAlgorithmParams.Type);
return builder.Build(trainingSet, classificationAlgorithmParams);
}
public NonTerminalNode(TrainingExample[] trainingExamples, int splittingFeature, Dictionary<int, DecisionTreeNode> childs)
{
TrainingExamples = trainingExamples;
SplittingFeature = splittingFeature;
Childs = childs;
}
