/// <summary>Create a classifier factory</summary>
/// <?/>
/// <returns>A factory to minimize a classifier against.</returns>
private static LinearClassifierFactory <L, string> InitFactory <L>(double sigma)
{
LinearClassifierFactory <L, string> factory = new LinearClassifierFactory <L, string>();
IFactory <IMinimizer <IDiffFunction> > minimizerFactory;
switch (minimizer)
{
case KBPStatisticalExtractor.MinimizerType.Qn:
{
minimizerFactory = null;
break;
}
case KBPStatisticalExtractor.MinimizerType.Sgd:
{
minimizerFactory = null;
break;
}
case KBPStatisticalExtractor.MinimizerType.Hybrid:
{
factory.UseHybridMinimizerWithInPlaceSGD(100, 1000, sigma);
minimizerFactory = null;
break;
}
case KBPStatisticalExtractor.MinimizerType.L1:
{
minimizerFactory = null;
break;
}
default:
{
throw new InvalidOperationException("Unknown minimizer: " + minimizer);
}
}
factory.SetMinimizerCreator(minimizerFactory);
return(factory);
}
/// <summary>Train a sentiment model from a set of data.</summary>
/// <param name="data">The data to train the model from.</param>
/// <param name="modelLocation">
/// An optional location to save the model.
/// Note that this stream will be closed in this method,
/// and should not be written to thereafter.
/// </param>
/// <returns>A sentiment classifier, ready to use.</returns>
public static SimpleSentiment Train(IStream <SimpleSentiment.SentimentDatum> data, Optional <OutputStream> modelLocation)
{
// Some useful variables configuring how we train
bool useL1 = true;
double sigma = 1.0;
int featureCountThreshold = 5;
// Featurize the data
Redwood.Util.ForceTrack("Featurizing");
RVFDataset <SentimentClass, string> dataset = new RVFDataset <SentimentClass, string>();
AtomicInteger datasize = new AtomicInteger(0);
ICounter <SentimentClass> distribution = new ClassicCounter <SentimentClass>();
data.Unordered().Parallel().Map(null).ForEach(null);
Redwood.Util.EndTrack("Featurizing");
// Print label distribution
Redwood.Util.StartTrack("Distribution");
foreach (SentimentClass label in SentimentClass.Values())
{
Redwood.Util.Log(string.Format("%7d", (int)distribution.GetCount(label)) + " " + label);
}
Redwood.Util.EndTrack("Distribution");
// Train the classifier
Redwood.Util.ForceTrack("Training");
if (featureCountThreshold > 1)
{
dataset.ApplyFeatureCountThreshold(featureCountThreshold);
}
dataset.Randomize(42L);
LinearClassifierFactory <SentimentClass, string> factory = new LinearClassifierFactory <SentimentClass, string>();
factory.SetVerbose(true);
try
{
factory.SetMinimizerCreator(null);
}
catch (Exception)
{
}
factory.SetSigma(sigma);
LinearClassifier <SentimentClass, string> classifier = factory.TrainClassifier(dataset);
// Optionally save the model
modelLocation.IfPresent(null);
Redwood.Util.EndTrack("Training");
// Evaluate the model
Redwood.Util.ForceTrack("Evaluating");
factory.SetVerbose(false);
double sumAccuracy = 0.0;
ICounter <SentimentClass> sumP = new ClassicCounter <SentimentClass>();
ICounter <SentimentClass> sumR = new ClassicCounter <SentimentClass>();
int numFolds = 4;
for (int fold = 0; fold < numFolds; ++fold)
{
Pair <GeneralDataset <SentimentClass, string>, GeneralDataset <SentimentClass, string> > trainTest = dataset.SplitOutFold(fold, numFolds);
LinearClassifier <SentimentClass, string> foldClassifier = factory.TrainClassifierWithInitialWeights(trainTest.first, classifier);
// convex objective, so this should be OK
sumAccuracy += foldClassifier.EvaluateAccuracy(trainTest.second);
foreach (SentimentClass label_1 in SentimentClass.Values())
{
Pair <double, double> pr = foldClassifier.EvaluatePrecisionAndRecall(trainTest.second, label_1);
sumP.IncrementCount(label_1, pr.first);
sumP.IncrementCount(label_1, pr.second);
}
}
DecimalFormat df = new DecimalFormat("0.000%");
log.Info("----------");
double aveAccuracy = sumAccuracy / ((double)numFolds);
log.Info(string.Empty + numFolds + "-fold accuracy: " + df.Format(aveAccuracy));
log.Info(string.Empty);
foreach (SentimentClass label_2 in SentimentClass.Values())
{
double p = sumP.GetCount(label_2) / numFolds;
double r = sumR.GetCount(label_2) / numFolds;
log.Info(label_2 + " (P) = " + df.Format(p));
log.Info(label_2 + " (R) = " + df.Format(r));
log.Info(label_2 + " (F1) = " + df.Format(2 * p * r / (p + r)));
log.Info(string.Empty);
}
log.Info("----------");
Redwood.Util.EndTrack("Evaluating");
// Return
return(new SimpleSentiment(classifier));
}
