/// <summary>Creates a new Edge.</summary>
/// <param name="source">Source for the.</param>
/// <param name="target">Target for the.</param>
/// <returns>An Edge.</returns>
public static Edge Create(Node source, Node target)
{
Edge e = new Edge { Source = source, Target = target };
source.Out.Add(e);
target.In.Add(e);
return e;
}
/// <summary>Defaults.</summary>
/// <param name="d">The Descriptor to process.</param>
/// <param name="x">The Vector to process.</param>
/// <param name="y">The Vector to process.</param>
/// <param name="activation">The activation.</param>
/// <returns>A Network.</returns>
public static Network Default(Descriptor d, Matrix x, Vector y, IFunction activation)
{
Network nn = new Network();
// set output to number of choices of available
// 1 if only two choices
int distinct = y.Distinct().Count();
int output = distinct > 2 ? distinct : 1;
// identity funciton for bias nodes
IFunction ident = new Ident();
// set number of hidden units to (Input + Hidden) * 2/3 as basic best guess.
int hidden = (int)System.Math.Ceiling((decimal)(x.Cols + output) * 2m / 3m);
// creating input nodes
nn.In = new Node[x.Cols + 1];
nn.In[0] = new Node { Label = "B0", Activation = ident };
for (int i = 1; i < x.Cols + 1; i++)
nn.In[i] = new Node { Label = d.ColumnAt(i - 1), Activation = ident };
// creating hidden nodes
Node[] h = new Node[hidden + 1];
h[0] = new Node { Label = "B1", Activation = ident };
for (int i = 1; i < hidden + 1; i++)
h[i] = new Node { Label = String.Format("H{0}", i), Activation = activation };
// creating output nodes
nn.Out = new Node[output];
for (int i = 0; i < output; i++)
nn.Out[i] = new Node { Label = GetLabel(i, d), Activation = activation };
// link input to hidden. Note: there are
// no inputs to the hidden bias node
for (int i = 1; i < h.Length; i++)
for (int j = 0; j < nn.In.Length; j++)
Edge.Create(nn.In[j], h[i]);
// link from hidden to output (full)
for (int i = 0; i < nn.Out.Length; i++)
for (int j = 0; j < h.Length; j++)
Edge.Create(h[j], nn.Out[i]);
return nn;
}
/// <summary>Gets the nodes in this collection.</summary>
/// <param name="n">The Node to process.</param>
/// <returns>
/// An enumerator that allows foreach to be used to process the nodes in this collection.
/// </returns>
private IEnumerable<Node> GetNodes(Node n)
{
foreach (var edge in n.In)
{
yield return edge.Source;
foreach (var node in this.GetNodes(edge.Source))
{
yield return node;
}
}
}
/// <summary>Gets the edges in this collection.</summary>
/// <param name="n">The Node to process.</param>
/// <returns>
/// An enumerator that allows foreach to be used to process the edges in this collection.
/// </returns>
private IEnumerable<Edge> GetEdges(Node n)
{
foreach (var edge in n.In)
{
yield return edge;
foreach (var e in this.GetEdges(edge.Source))
{
yield return e;
}
}
}
/// <summary>Generates an object from its XML representation.</summary>
/// <param name="reader">The <see cref="T:System.Xml.XmlReader" /> stream from which the object is
/// deserialized.</param>
public void ReadXml(XmlReader reader)
{
XmlSerializer nSerializer = new XmlSerializer(typeof(Node));
XmlSerializer eSerializer = new XmlSerializer(typeof(Edge));
reader.MoveToContent();
Dictionary<string, Node> nodes = new Dictionary<string, Node>();
int length = 0;
reader.ReadStartElement();
length = int.Parse(reader.GetAttribute("Length"));
reader.ReadStartElement("Nodes");
for (int i = 0; i < length; i++)
{
var node = (Node)nSerializer.Deserialize(reader);
nodes.Add(node.Id, node);
reader.Read();
}
reader.ReadEndElement();
length = int.Parse(reader.GetAttribute("Length"));
reader.ReadStartElement("Edges");
for (int i = 0; i < length; i++)
{
var edge = (Edge)eSerializer.Deserialize(reader);
reader.Read();
edge.Source = nodes[edge.SourceId];
edge.Target = nodes[edge.TargetId];
edge.Source.Out.Add(edge);
edge.Target.In.Add(edge);
}
reader.ReadEndElement();
length = int.Parse(reader.GetAttribute("Length"));
reader.ReadStartElement("In");
In = new Node[length];
for (int i = 0; i < length; i++)
{
reader.MoveToContent();
In[i] = nodes[reader.GetAttribute("Id")];
reader.Read();
}
reader.ReadEndElement();
length = int.Parse(reader.GetAttribute("Length"));
reader.ReadStartElement("Out");
Out = new Node[length];
for (int i = 0; i < length; i++)
{
reader.MoveToContent();
Out[i] = nodes[reader.GetAttribute("Id")];
reader.Read();
}
reader.ReadEndElement();
}
