public void LearnTest7()
{
// Create continuous sequences. In the sequences below, there
// seems to be two states, one for values between 0 and 1 and
// another for values between 5 and 7. The states seems to be
// switched on every observation.
double[][] sequences = new double[][]
{
new double[] { 0.1, 5.2, 0.3, 6.7, 0.1, 6.0 },
new double[] { 0.2, 6.2, 0.3, 6.3, 0.1, 5.0 },
new double[] { 0.1, 7.0, 0.1, 7.0, 0.2, 5.6 },
};
// Specify a initial normal distribution for the samples.
var density = new NormalDistribution();
// Creates a continuous hidden Markov Model with two states organized in a forward
// topology and an underlying univariate Normal distribution as probability density.
var model = new HiddenMarkovModel<NormalDistribution>(new Ergodic(2), density);
// Configure the learning algorithms to train the sequence classifier until the
// difference in the average log-likelihood changes only by as little as 0.0001
var teacher = new BaumWelchLearning<NormalDistribution>(model)
{
Tolerance = 0.0001,
Iterations = 0,
};
// Fit the model
double logLikelihood = teacher.Run(sequences);
// See the log-probability of the sequences learned
double a1 = model.Evaluate(new[] { 0.1, 5.2, 0.3, 6.7, 0.1, 6.0 }); // -0.12799388666109757
double a2 = model.Evaluate(new[] { 0.2, 6.2, 0.3, 6.3, 0.1, 5.0 }); // 0.01171157434400194
// See the probability of an unrelated sequence
double a3 = model.Evaluate(new[] { 1.1, 2.2, 1.3, 3.2, 4.2, 1.0 }); // -298.7465244473417
double likelihood = Math.Exp(logLikelihood);
a1 = Math.Exp(a1); // 0.879
a2 = Math.Exp(a2); // 1.011
a3 = Math.Exp(a3); // 0.000
// We can also ask the model to decode one of the sequences. After
// this step the resulting sequence will be: { 0, 1, 0, 1, 0, 1 }
//
int[] states = model.Decode(new[] { 0.1, 5.2, 0.3, 6.7, 0.1, 6.0 });
Assert.IsTrue(states.IsEqual(new[] { 0, 1, 0, 1, 0, 1 }));
Assert.AreEqual(1.496360383340358, likelihood, 1e-10);
Assert.AreEqual(0.8798587580029778, a1, 1e-10);
Assert.AreEqual(1.0117804233450216, a2, 1e-10);
Assert.AreEqual(1.8031545195073828E-130, a3, 1e-10);
Assert.IsFalse(double.IsNaN(logLikelihood));
Assert.IsFalse(double.IsNaN(a1));
Assert.IsFalse(double.IsNaN(a2));
Assert.IsFalse(double.IsNaN(a3));
Assert.AreEqual(2, model.Emissions.Length);
var state1 = (model.Emissions[0] as NormalDistribution);
var state2 = (model.Emissions[1] as NormalDistribution);
Assert.AreEqual(0.16666666666666, state1.Mean, 1e-10);
Assert.AreEqual(6.11111111111111, state2.Mean, 1e-10);
Assert.IsFalse(Double.IsNaN(state1.Mean));
Assert.IsFalse(Double.IsNaN(state2.Mean));
Assert.AreEqual(0.007499999999999, state1.Variance, 1e-10);
Assert.AreEqual(0.538611111111111, state2.Variance, 1e-10);
Assert.IsFalse(Double.IsNaN(state1.Variance));
Assert.IsFalse(Double.IsNaN(state2.Variance));
Assert.AreEqual(2, model.Transitions.GetLength(0));
Assert.AreEqual(2, model.Transitions.GetLength(1));
var A = model.Transitions.Exp();
Assert.AreEqual(0, A[0, 0], 1e-16);
Assert.AreEqual(1, A[0, 1], 1e-16);
Assert.AreEqual(1, A[1, 0], 1e-16);
Assert.AreEqual(0, A[1, 1], 1e-16);
Assert.IsFalse(A.HasNaN());
}
