internal void RemoveConnection(Connection connection)
{
if(connection.FromNode == this) {
OutgoingConnections.Remove(connection);
} else if(connection.ToNode == this) {
IncommingConnections.Remove(connection);
}
}
internal void AddOutgoingConnection(Connection connection)
{
if(connection.FromNode == this && connection.ToNode != null) {
OutgoingConnections.Add(connection);
} else {
throw new ArgumentException("Invalid connection");
}
}
public static Connection Create(double weight, Node fromNode, Node toNode)
{
var con = new Connection(weight, fromNode, toNode);
fromNode.AddOutgoingConnection(con);
toNode.AddIncommingConnection(con);
return con;
}
public static void Delete(Connection connection)
{
connection.FromNode.RemoveConnection(connection);
connection.ToNode.RemoveConnection(connection);
}
/// <summary>
/// Calculates connection influence value IF it is not yet present in ConnectionInfluence dictionary
/// Stores result in the dictionary and then returns it
/// </summary>
private double GetConnectionInfluence(Connection connection, int microBatchIndex) {
double? cur = ConnectionInfluence[connection][microBatchIndex];
if(cur.HasValue) {
return cur.Value;
} else {
double sumInfluenceOutput = 0;
foreach(var outgoing in connection.ToNode.GetOutgoingConnections()) {
double connectionInfluence = GetConnectionInfluence(outgoing, microBatchIndex);
double curInfluence = connectionInfluence * outgoing.Weight;
sumInfluenceOutput += curInfluence;
}
double fromOutput = connection.FromNode.Output;
double outDeriv = Network.TransferFunction.Derivative(connection.ToNode.Output);
double influence = sumInfluenceOutput * outDeriv;
ConnectionInfluence[connection][microBatchIndex] = influence;
return influence;
}
}
private double CalcOutputInfuence(Connection connection, double expectedOutput, double actualOutput) {
double dif = (-(expectedOutput - actualOutput));
double outcome = dif * Network.TransferFunction.Derivative(actualOutput);
return outcome;
}