/// <summary>
/// Raises the <see cref="E:GenerativeClassModelLearningStarted"/> event.
/// </summary>
///
/// <param name="args">The <see cref="Accord.Statistics.Models.Markov.Learning.GenerativeLearningEventArgs"/> instance containing the event data.</param>
///
protected void OnGenerativeClassModelLearningStarted(GenerativeLearningEventArgs args)
{
if (ClassModelLearningStarted != null)
{
ClassModelLearningStarted(this, args);
}
}
private void LearnInner(TObservation[][] x, int[] y, int i, int classes, double[] logLikelihood, int[] classCounts)
{
// We will start the class model learning problem
Trace.WriteLine(String.Format("Starting: {0}", i));
var args = new GenerativeLearningEventArgs(i, classes);
OnGenerativeClassModelLearningStarted(args);
// Select the input/output set corresponding
// to the model's specialization class
int[] idx = y.Find(y_j => y_j == i);
TObservation[][] observations = x.Get(idx);
classCounts[i] = observations.Length;
if (observations.Length > 0)
{
// Create and configure the learning algorithm
var innerModelTeacher = Learner(i);
var innerModel = innerModelTeacher.Learn(observations);
Classifier.Models[i] = innerModel;
logLikelihood[i] = innerModel.LogLikelihood(observations).Sum();
}
// Update and report progress
Trace.WriteLine(String.Format("Done: {0} ", i));
OnGenerativeClassModelLearningFinished(args);
}
/// <summary>
/// Trains each model to recognize each of the output labels.
/// </summary>
/// <returns>The sum log-likelihood for all models after training.</returns>
///
protected double Run<T>(T[] inputs, int[] outputs)
{
if (inputs == null) throw new ArgumentNullException("inputs");
if (outputs == null) throw new ArgumentNullException("outputs");
if (inputs.Length != outputs.Length)
throw new DimensionMismatchException("outputs",
"The number of inputs and outputs does not match.");
for (int i = 0; i < outputs.Length; i++)
if (outputs[i] < 0 || outputs[i] >= Classifier.Classes)
throw new ArgumentOutOfRangeException("outputs");
int classes = Classifier.Classes;
double[] logLikelihood = new double[classes];
int[] classCounts = new int[classes];
// For each model,
#if !DEBUG
Parallel.For(0, classes, i =>
#else
for (int i = 0; i < classes; i++)
#endif
{
// We will start the class model learning problem
var args = new GenerativeLearningEventArgs(i, classes);
OnGenerativeClassModelLearningStarted(args);
// Select the input/output set corresponding
// to the model's specialization class
int[] inx = outputs.Find(y => y == i);
T[] observations = inputs.Submatrix(inx);
classCounts[i] = observations.Length;
if (observations.Length > 0)
{
// Create and configure the learning algorithm
IUnsupervisedLearning teacher = Algorithm(i);
// Train the current model in the input/output subset
logLikelihood[i] = teacher.Run(observations as Array[]);
}
// Update and report progress
OnGenerativeClassModelLearningFinished(args);
}
/// <summary>
/// Learns a model that can map the given inputs to the given outputs.
/// </summary>
/// <param name="x">The model inputs.</param>
/// <param name="y">The desired outputs associated with each <paramref name="x">inputs</paramref>.</param>
/// <param name="weights">The weight of importance for each input-output pair.</param>
/// <returns>
/// A model that has learned how to produce <paramref name="y" /> given <paramref name="x" />.
/// </returns>
public TClassifier Learn(TObservation[][] x, int[] y, double[] weights = null)
{
if (x.Length != y.Length)
{
throw new DimensionMismatchException("outputs",
"The number of inputs and outputs does not match.");
}
for (int i = 0; i < y.Length; i++)
{
if (y[i] < 0 || y[i] >= Classifier.Classes)
{
throw new ArgumentOutOfRangeException("outputs");
}
}
int classes = Classifier.Classes;
double[] logLikelihood = new double[classes];
int[] classCounts = new int[classes];
// For each model,
Parallel.For(0, classes, i =>
{
// We will start the class model learning problem
var args = new GenerativeLearningEventArgs(i, classes);
OnGenerativeClassModelLearningStarted(args);
// Select the input/output set corresponding
// to the model's specialization class
int[] inx = y.Find(y_j => y_j == i);
TObservation[][] observations = x.Get(inx);
classCounts[i] = observations.Length;
if (observations.Length > 0)
{
// Create and configure the learning algorithm
var teacher = Learner(i);
var model = teacher.Learn(observations);
logLikelihood[i] = model.LogLikelihood(observations).Sum();
}
// Update and report progress
OnGenerativeClassModelLearningFinished(args);
});
if (Empirical)
{
for (int i = 0; i < classes; i++)
{
Classifier.Priors[i] = (double)classCounts[i] / x.Length;
}
}
if (Rejection)
{
Classifier.Threshold = Threshold();
}
LogLikelihood = logLikelihood.Sum();
return(Classifier);
}
protected double Run <T>(T[] inputs, int[] outputs)
{
if (inputs == null)
{
throw new ArgumentNullException("inputs");
}
if (outputs == null)
{
throw new ArgumentNullException("outputs");
}
if (inputs.Length != outputs.Length)
{
throw new DimensionMismatchException("outputs",
"The number of inputs and outputs does not match.");
}
for (int i = 0; i < outputs.Length; i++)
{
if (outputs[i] < 0 || outputs[i] >= Classifier.Classes)
{
throw new ArgumentOutOfRangeException("outputs");
}
}
int classes = Classifier.Classes;
double[] logLikelihood = new double[classes];
int[] classCounts = new int[classes];
// For each model,
Parallel.For(0, classes, i =>
{
// We will start the class model learning problem
var args = new GenerativeLearningEventArgs(i, classes);
OnGenerativeClassModelLearningStarted(args);
// Select the input/output set corresponding
// to the model's specialization class
int[] inx = outputs.Find(y => y == i);
T[] observations = inputs.Get(inx);
classCounts[i] = observations.Length;
if (observations.Length > 0)
{
// Create and configure the learning algorithm
// Backward compatibility case
var teacher = Algorithm(i);
// Train the current model in the input/output subset
logLikelihood[i] = teacher.Run(observations as Array[]);
}
// Update and report progress
OnGenerativeClassModelLearningFinished(args);
});
if (Empirical)
{
for (int i = 0; i < classes; i++)
{
Classifier.Priors[i] = (double)classCounts[i] / inputs.Length;
}
}
if (Rejection)
{
Classifier.Threshold = Threshold();
}
// Returns the sum log-likelihood for all models.
return(logLikelihood.Sum());
}
