/// <summary>
/// Initializes the <see cref="StochasticLayer"/>.
/// </summary>
/// <param name="direction">The cell direction (forward-only or bi-directional).</param>
/// <param name="numberOfNeurons">The number of neurons in the layer.</param>
/// <param name="matrixLayout">Specifies whether the weight matrices are row-major or column-major.</param>
/// <param name="weightsShape">The dimensions of the layer's weights tensor.</param>
/// <param name="hiddenShape">The dimensions of the layer's hidden weights tensor.</param>
/// <param name="biasesShape">The dimensions of the layer's biases tensor.</param>
/// <param name="random">The random numbers generator.</param>
private protected void Initialize(
RNNDirection direction,
int numberOfNeurons,
MatrixLayout matrixLayout,
int[] weightsShape,
int[] hiddenShape,
int[] biasesShape,
RandomNumberGenerator <float> random)
{
if (hiddenShape == null)
{
throw new ArgumentNullException(nameof(hiddenShape));
}
if (random == null)
{
random = new RandomRangeGenerator(-0.08f, 0.08f);
}
if (direction == RNNDirection.BiDirectional && (numberOfNeurons % 2) != 0)
{
throw new ArgumentException("The number of neurons in a bi-directional RNN must be even.", nameof(numberOfNeurons));
}
this.Direction = direction;
this.Initialize(numberOfNeurons, matrixLayout, weightsShape, biasesShape, random);
this.U = new Tensor("hidden weights", hiddenShape);
this.U.Randomize(random);
}
/*[TestMethod]
* public void TrainTest2()
* {
* const int LearnCount = 100;
* const int TestCount = 1000;
* const int Length = 300;
* const double PositiveRatio = 0.1;
*
* // create samples
* List<(double[] x, bool y, double weight)> samples = SupportVectorMachineTest.GenerateSamples(LearnCount + TestCount, Length, PositiveRatio).ToList();
*
* // learn
* SequentialMinimalOptimization<Accord.Statistics.Kernels.IKernel> optimization = new SequentialMinimalOptimization<Accord.Statistics.Kernels.IKernel>()
* {
* Kernel = new Accord.Statistics.Kernels.ChiSquare(),
* Tolerance = 0.01f,
* Strategy = SelectionStrategy.SecondOrder
* };
*
* optimization.Learn(
* samples.Take(LearnCount).Select(x => x.x.Select(w => (double)w).ToArray()).ToArray(),
* samples.Take(LearnCount).Select(x => x.y).ToArray());
* }*/
private static IEnumerable <(double[] x, bool y, double weight)> GenerateSamples(int count, int length, double positiveRatio)
{
Random random = new Random(0);
BinarySampleGenerator sampleGenerator = new BinarySampleGenerator(positiveRatio, random);
double[] weights = new RandomRangeGenerator(-1, 1, random).Generate(length).Select(x => (double)x).ToArray();
while (count > 0)
{
double[] sample = sampleGenerator.Generate(length).Select(x => x ? 1.0 : 0.0).ToArray();
double res = Matrix.DotProduct(length, sample, 0, weights, 0);
if (res >= 1)
{
yield return(sample, true, 1.0f);
count--;
}
else if (res <= -1)
{
yield return(sample, false, 1.0f);
count--;
}
}
}
/// <summary>
/// Initializes the <see cref="GRUCell"/>.
/// </summary>
/// <param name="shape">The dimensions of the layer's input tensor.</param>
/// <param name="direction">The cell direction (forward-only or bi-directional).</param>
/// <param name="numberOfNeurons">The number of neurons in the layer.</param>
/// <param name="matrixLayout">Specifies whether the weight matrices are row-major or column-major.</param>
/// <param name="random">The random numbers generator.</param>
private void Initialize(
Shape shape,
RNNDirection direction,
int numberOfNeurons,
MatrixLayout matrixLayout,
RandomNumberGenerator <float> random)
{
if (shape == null)
{
throw new ArgumentNullException(nameof(shape));
}
if (random == null)
{
random = new RandomRangeGenerator(-0.08f, 0.08f);
}
int[] axes = shape.Axes;
// column-major matrix organization - each row contains all weights for one neuron
// row-major matrix organization - each column contains all weights for one neuron
int xlen = axes.Skip(1).Aggregate(1, (total, next) => total * next);
int[] weightsShape = matrixLayout == MatrixLayout.ColumnMajor ?
new[] { xlen, 3 * numberOfNeurons } :
new[] { 3 * numberOfNeurons, xlen };
// keep all weights in single channel
// allocate three matrices (one for each of two gates and one for the state)
int[] biasesShape = new[] { 3 * numberOfNeurons };
int hlen = direction == RNNDirection.ForwardOnly ? numberOfNeurons : numberOfNeurons / 2;
int[] hiddenShape = matrixLayout == MatrixLayout.ColumnMajor ?
new[] { hlen, 3 * numberOfNeurons } :
new[] { 3 * numberOfNeurons, hlen };
this.Initialize(
direction,
numberOfNeurons,
matrixLayout,
weightsShape,
hiddenShape,
biasesShape,
random ?? new RandomRangeGenerator(-0.08f, 0.08f));
this.OutputShape = new Shape(new int[] { shape.GetAxis(0), numberOfNeurons });
// initialize biases for update and reset gates only
Vectors.Set(2 * numberOfNeurons, 1.0f, this.B.Weights, 0);
}