/// <summary>Samples a single position in the sequence.</summary>
/// <remarks>
/// Samples a single position in the sequence.
/// Does not modify the sequence passed in.
/// returns the score of the new label for the position to sample
/// </remarks>
/// <param name="sequence">the sequence to start with</param>
/// <param name="pos">the position to sample.</param>
/// <param name="temperature">the temperature to control annealing</param>
private Pair <int, double> SamplePositionHelper(ISequenceModel model, int[] sequence, int pos, double temperature)
{
double[] distribution = model.ScoresOf(sequence, pos);
if (temperature != 1.0)
{
if (temperature == 0.0)
{
// set the max to 1.0
int argmax = ArrayMath.Argmax(distribution);
Arrays.Fill(distribution, double.NegativeInfinity);
distribution[argmax] = 0.0;
}
else
{
// take all to a power
// use the temperature to increase/decrease the entropy of the sampling distribution
ArrayMath.MultiplyInPlace(distribution, 1.0 / temperature);
}
}
ArrayMath.LogNormalize(distribution);
ArrayMath.ExpInPlace(distribution);
int newTag = ArrayMath.SampleFromDistribution(distribution, random);
double newProb = distribution[newTag];
return(new Pair <int, double>(newTag, newProb));
}
public virtual void TestExpLogInplace()
{
ArrayMath.ExpInPlace(d1);
ArrayMath.LogInPlace(d1);
ArrayMath.PairwiseSubtractInPlace(d1, d2);
double norm2 = ArrayMath.Norm(d1);
NUnit.Framework.Assert.AreEqual(norm2, 1e-5, 0.0);
}
