/// <summary>
/// This version starts with a SOM, then potentially splits the largest node and/or gathers the smallest nodes into a single
/// </summary>
/// <returns></returns>
public static SOMResult Train(ISOMInput[] inputs, SOMRules rules, bool isDisplay2D)
{
SOMResult result = SelfOrganizingMaps.TrainSOM(inputs, rules, isDisplay2D);
if (result.Nodes.Length == 0)
{
return(result);
}
else if (result.Nodes.Length == 1)
{
#region kmeans single node
if (inputs.Length < 20)
{
return(result);
}
return(SelfOrganizingMaps.TrainKMeans(inputs, 5, true));
#endregion
}
var categorized = GetSOM_SplitMerge_Categorize(result);
List <SOMNode> nodes = new List <SOMNode>();
List <ISOMInput[]> newInputs = new List <ISOMInput[]>();
foreach (NodeCombo set in UtilityCore.Iterate(categorized.kmeans, categorized.keep)) // UtilityCore.Iterate gracefully skips nulls
{
nodes.Add(set.Node);
newInputs.Add(set.Inputs);
}
if (categorized.remaining != null)
{
nodes.Add(new SOMNode()
{
Position = MathND.GetCenter(categorized.remaining.Select(o => o.Node.Position)),
Weights = MathND.GetCenter(categorized.remaining.Select(o => o.Node.Weights)),
});
newInputs.Add(categorized.remaining.
SelectMany(o => o.Inputs).
ToArray());
}
return(new SOMResult(nodes.ToArray(), newInputs.ToArray(), false));
}
private static (NodeCombo[] kmeans, NodeCombo[] keep, NodeCombo[] remaining) GetSOM_SplitMerge_Categorize(SOMResult result)
{
NodeCombo[] nodes = Enumerable.Range(0, result.Nodes.Length).
Select(o => new NodeCombo()
{
Node = result.Nodes[o], Inputs = result.InputsByNode[o]
}).
OrderByDescending(o => o.Inputs.Length).
ToArray();
// First node is a potential kmeans split
NodeCombo kmeans = null;
int keepStart = 0;
if (nodes[0].Inputs.Length.ToDouble() / nodes[1].Inputs.Length.ToDouble() > 10)
{
kmeans = nodes[0];
keepStart = 1;
}
NodeCombo[] kmeansSplit = null;
if (kmeans != null)
{
SOMResult result2 = SelfOrganizingMaps.TrainKMeans(kmeans.Inputs, 4, true);
kmeansSplit = Enumerable.Range(0, result2.Nodes.Length).
Select(o => new NodeCombo()
{
Node = result2.Nodes[o], Inputs = result2.InputsByNode[o]
}).
ToArray();
}
// Next nodes are the ones to leave alone
var keep = new List <NodeCombo>();
int?keepStop = null;
keep.Add(nodes[keepStart]);
for (int cntr = keepStart + 1; cntr < nodes.Length; cntr++)
{
if (nodes[keepStart].Inputs.Length.ToDouble() / nodes[cntr].Inputs.Length.ToDouble() > 10)
{
keepStop = cntr;
break;
}
keep.Add(nodes[cntr]);
}
// Everything else gets merged into a single node
NodeCombo[] remaining = null;
if (keepStop != null)
{
remaining = Enumerable.Range(keepStop.Value, result.Nodes.Length - keepStop.Value).
Select(o => nodes[o]).
ToArray();
}
if (remaining == null && keep.Count > 0 && kmeans != null)
{
int sumKeep = keep.Sum(o => o.Inputs.Length);
int smallestKmeans = kmeansSplit.
Select(o => o.Inputs.Length).
OrderBy(o => o).
First();
if (smallestKmeans.ToDouble() / sumKeep.ToDouble() > 10)
{
remaining = keep.ToArray();
keep.Clear();
}
}
return(kmeansSplit, keep.ToArray(), remaining);
}
