public ClassifierBuildResult Build(TextDocument[] trainingSet, EnsembleParams ensembleParams) { var classifiers = ensembleParams.ClassifiersParams.Select(x => Build(trainingSet, ensembleParams.BaggingParams, x)).ToArray(); var result = new ClassifiersEnsemble(classifiers); return ClassifierBuildResult.Create(result, trainingSet, ensembleParams.TargetTag); }
public ClassifierBuildResult Build(TextDocument[] trainingSet, EnsembleParams ensembleParams) { var weightedDocuments = trainingSet.Select((x, i) => new WeightedDocument { Document = x, Weight = 1.0 / trainingSet.Length }).ToArray(); var classifiers = new List<WeightedClassifier>(); var classifierParamses = ensembleParams.ClassifiersParams; var targetTag = ensembleParams.TargetTag; for (int iteration = 0; iteration < classifierParamses.Length; iteration++) { Console.WriteLine("Running {0}/{1} boosting iteration", iteration + 1, classifierParamses.Length); var sampledTrainingSet = DoSampling(weightedDocuments); var binaryClassifierBuildResult = classifierBuilder.Build(sampledTrainingSet, classifierParamses[iteration]); var classifier = binaryClassifierBuildResult.Classifier; var error = weightedDocuments.Sum(x => classifier.IsClassifierWrong(x.Document, targetTag) ? x.Weight : 0); var alpha = 0.5 * Math.Log((1.0 - error) / error); foreach (var weightedDocument in weightedDocuments) { if (classifier.IsClassifierWrong(weightedDocument.Document, targetTag)) weightedDocument.Weight *= Math.Exp(alpha); else weightedDocument.Weight *= Math.Exp(-alpha); } var z = weightedDocuments.Sum(x => x.Weight); foreach (var weightedDocument in weightedDocuments) { weightedDocument.Weight /= z; } classifiers.Add(new WeightedClassifier { Classifier = classifier, Weight = alpha }); Console.WriteLine("Error (weighted) = {0}", error); Console.WriteLine("Alpha = {0}", alpha); var evaluationResult = classifierEvaluator.Evaluate(classifier, trainingSet, targetTag); Console.WriteLine("FScore = {0}", evaluationResult.FScore); } var result = new ClassifiersEnsemble(classifiers); return ClassifierBuildResult.Create(result, trainingSet, targetTag); }
public ClassifierBuildResult Build(TextDocument[] trainingSet, EnsembleParams ensembleParams) { var builder = builders.First(x => x.Type == ensembleParams.Type); return builder.Build(trainingSet, ensembleParams); }