public DecisionTreeImplementation(string[,] attributes, List <string> labels)
{
parent = null;
BuildTree(attributes, labels);
}
private void BuildTree(string[,] attributes, List <string> labels)
{
int numInstances = labels.Count;
double nodeInformation = numInstances * CalcularEntropia(labels);
this.majorityClass = ObtenerValorMasFrecuente(labels);
if (nodeInformation == 0 || attributes.GetUpperBound(0) == -1 || attributes.GetUpperBound(1) == -1)
{
isLeaf = true;
return;
}
int bestAttributeId = -1;
string bestAttribute = "";
double bestInformationGain = -1;
double bestGainRatio = -1;
for (int X = 0; X < attributes.GetUpperBound(1) + 1; X++)
{
double conditionalInfo = 0;
double attributeEntropy = 0;
string[] valoresColumna = ObtenerValoresUnicos(attributes, X);
double[] attributeCount = new double[valoresColumna.Length];
for (int Y = 0; Y < valoresColumna.Length; Y++)
{
List <int> ids = IdentificarOcurrencias(ObtenerValoresColumna(attributes, X), valoresColumna[Y]); // get ids of all instances for which attribute X == Y
attributeCount[Y] = ids.Count;
double entropiaCalculada = CalcularEntropia(ObtenerListaValoresFiltrada(labels, ids));
conditionalInfo += attributeCount[Y] * entropiaCalculada;
}
double attributeInformationGain = nodeInformation - conditionalInfo;
double gainRatio = attributeInformationGain / CalcularEntropia(ObtenerValoresColumna(attributes, X));
if (gainRatio > bestGainRatio)
{
bestInformationGain = attributeInformationGain;
bestGainRatio = gainRatio;
bestAttribute = attributes[0, X];
bestAttributeId = X;
}
}
// If no attribute provides andy gain, this node cannot be split further
if (bestGainRatio == 0)
{
@isLeaf = true;
return;
}
// Otherwise split by the best attribute
this.bestAttributeId = bestAttributeId;
this.bestAttribute = bestAttribute;
this.nodeGainRatio = bestGainRatio;
this.nodeInformationGain = bestInformationGain;
string[] valoresMejorColumna = ObtenerValoresUnicos(attributes, bestAttributeId);
for (int Y = 0; Y < valoresMejorColumna.Length; Y++)
{
List <string> valores = ObtenerValoresColumna(attributes, bestAttributeId);
string valorEvaluar = valoresMejorColumna[Y];
List <int> ids = IdentificarOcurrencias(valores, valorEvaluar);
//this.children.Add(valoresMejorColumna[Y], new DecisionTree(ObtenerMatrizValoresFiltrada(attributes, ids), ObtenerListaValoresFiltrada(labels, ids)));
//this.children[valoresMejorColumna[Y]].parent = this;
// NUEVO
string[,] atributosNuevoArbol = EliminarColumna(attributes, bestAttributeId);
atributosNuevoArbol = ObtenerMatrizValoresFiltrada(atributosNuevoArbol, ids);
//List<string> nuevasEtiquetas = ObtenerListaValoresFiltrada(valores, ids);
List <string> nuevasEtiquetas = ObtenerListaValoresFiltrada(labels, ids);
this.children.Add(valoresMejorColumna[Y], new DecisionTreeImplementation(atributosNuevoArbol, nuevasEtiquetas));
this.children[valoresMejorColumna[Y]].parent = this;
}
return;
}
