/// <summary>
/// Computes all neurons
/// </summary>
/// <param name="prev">Previous layer neurons</param>
public void ComputeNodes(Layer prev)
{
StreamWriter writer = new StreamWriter("E:/log.txt", true);
if (loggingEnabled)
{
writer.WriteLine("---- Layer Compute ----");
}
for (int i = 0; i < nodes.Length; i++)
{
this.nodes[i] = 0;
for (int j = 0; j < prev.nodes.Length; j++)
{
nodes[i] += Sigmoid.Activation(prev.nodes[j]) * weights[j, i];
}
if (loggingEnabled)
{
writer.WriteLine($"Node№ {i} : value = {nodes[i]} + bias {biases[i]}");
}
nodes[i] += biases[i];
//nodes[i] = Sigmoid.Activation(nodes[i]); // Not needed. Sigmoid activation applied upon next neuron call
}
writer.Flush();
writer.Close();
}
/// <summary>
/// Computes all neurons in all layers.
/// </summary>
/// <param name="input">Input vector</param>
/// <returns>Vector of probabilities</returns>
public double[] Compute(double[] input)
{
double[] output = new double[outputLayer.number];
inputLayer.nodes = input;
hiddenLayers[0].ComputeNodes(inputLayer);
for (int i = 1; i < hiddenLayers.Count; i++)
{
hiddenLayers[i].ComputeNodes(hiddenLayers[i - 1]);
}
outputLayer.ComputeNodes(hiddenLayers[hiddenLayers.Count - 1]);
for (int i = 0; i < outputLayer.number; i++)
{
output[i] = Sigmoid.Activation(outputLayer.nodes[i]);
}
return(output);
}
/// <summary>
/// Computes changes by backpropagating errors
/// </summary>
/// <param name="errors">Vector of error values</param>
/// <param name="speed">Speed modifier</param>
/// <param name="prevLayer">Previous layer neurons</param>
/// <returns>Errors of previous layer</returns>
public virtual double[] Propagate(double[] errors, double speed, Layer prevLayer)
{
StreamWriter writer = new StreamWriter("E:/log.txt", true);
if (loggingEnabled)
{
writer.WriteLine("---- Layer Error Correction ----");
}
double[] prevErrors = new double[prevLayer.number];
for (int i = 0; i < this.number; i++)
{
for (int j = 0; j < prevLayer.number; j++)
{
prevErrors[i] += errors[i] * weights[j, i];
}
if (loggingEnabled)
{
writer.WriteLine($"Eror {i} : value = {prevErrors[i]}");
}
prevErrors[i] = Sigmoid.ActivationDerivative(prevErrors[i]);
if (loggingEnabled)
{
writer.WriteLine($"Error deactivated {i} : value = {prevErrors[i]}");
}
for (int j = 0; j < prevLayer.number; j++)
{
weightCorrection[j, i] = speed * prevErrors[i] * Sigmoid.Activation(prevLayer.nodes[j]);
if (loggingEnabled)
{
//writer.WriteLine($"Weight correction [{i},{j}] : value = { weightCorrection[j, i]}");
}
}
biasCorrecton[i] = prevErrors[i] * speed;
if (loggingEnabled)
{
writer.WriteLine($"Bias correction {i} : value = {biasCorrecton[i]}");
}
}
writer.Flush();
writer.Close();
return(prevErrors);
}
/// <summary>
/// Computes changes by backpropagating errors.
/// </summary>
/// <param name="errors">Vector of error values</param>
/// <param name="speed">Speed modifier</param>
/// <param name="prevLayer">Previous layer neurons</param>
/// <returns>Errors of previous layer</returns>
public override double[] Propagate(double[] errors, double speed, Layer prevLayer)
{
double[] prevErrors = new double[prevLayer.number];
for (int i = 0; i < this.number; i++)
{
for (int j = 0; j < prevLayer.number; j++)
{
prevErrors[i] += errors[i] * weights[j, i];
}
for (int j = 0; j < prevLayer.number; j++)
{
weightCorrection[j, i] = speed * errors[i] * Sigmoid.Activation(prevLayer.nodes[j]);
}
biasCorrecton[i] = speed * errors[i];
}
return(errors);
}
/// <summary>
/// Computes all neurons in all layers, propagetes error.
/// </summary>
/// <param name="input">Input vector</param>
/// <param name="expected">Vector of expected result probabilities</param>
/// <returns>Vector of probabilities</returns>
public double[] Learn(double[] input, double[] expected)
{
double[] result = this.Compute(input);
double[] errors = new double[outputLayer.number];
for (int i = 0; i < result.Length; i++)
{
errors[i] = (expected[i] - result[i]) * Sigmoid.ActivationDerivative(outputLayer.nodes[i]);
}
double[] prevErrors = outputLayer.Propagate(errors, speed, hiddenLayers.Last());
prevErrors = hiddenLayers.Last().Propagate(errors, speed, outputLayer);
for (int i = hiddenLayers.Count - 1; i >= 0; i--)
{
prevErrors = hiddenLayers[i].Propagate(prevErrors, speed, hiddenLayers[i + 1]);
}
foreach (var item in hiddenLayers)
{
item.Apply();
}
outputLayer.Apply();
return(result);
}
