/// <summary>
/// This function will calculate the discrete Attribute's Entropy value
/// </summary>
/// <param name="attributes">an array of discrete attribute value</param>
/// <param name="classNumbers">a list of class numbers</param>
/// <returns>the entropy value</returns>
public double CalcAttributeGini(string[] attributes, byte[] classNumbers)
{
IList <string> uniqValues = new List <string>();
IList <int> samplesCount = new List <int>();
GetUniqValuesSamples <string>(attributes, out uniqValues, out samplesCount);
double AttributeEntro = 1.0;
long total = classNumbers.Length;
CombinationGenerator <string> cg = new CombinationGenerator <string>();
IEnumerable <List <string> > potentialCombinations = cg.ProduceWithoutRecursion(uniqValues as List <string>);
foreach (List <string> combination in potentialCombinations)
{
if (combination.Count != 0 && combination.Count == uniqValues.Count)
{
IList <byte> subsetClass = new List <byte>();
//in
splitVectorByContainage(attributes, classNumbers, combination, true, out subsetClass);
byte[] inClassArray = convertList2Array(subsetClass);
IList <byte> uniqClass = new List <byte>();
IList <int> uniqClassSamples = new List <int>();
GetUniqValuesSamples(inClassArray, out uniqClass, out uniqClassSamples);
double inEntropy = getGiniValuefromProbability(uniqClassSamples);
long subTotal = 0;
foreach (int value in uniqClassSamples)
{
subTotal += value;
}
inEntropy = inEntropy * ((subTotal * 1.0) / total);
//Not in
splitVectorByContainage(attributes, classNumbers, combination, true, out subsetClass);
byte[] notInClassArray = convertList2Array(subsetClass);
uniqClass = new List <byte>();
uniqClassSamples = new List <int>();
GetUniqValuesSamples(inClassArray, out uniqClass, out uniqClassSamples);
double notInEntropy = getGiniValuefromProbability(uniqClassSamples);
subTotal = 0;
foreach (int value in uniqClassSamples)
{
subTotal += value;
}
notInEntropy = notInEntropy * ((subTotal * 1.0) / total);
if (inEntropy + notInEntropy < AttributeEntro)
{
AttributeEntro = inEntropy + notInEntropy;
}
}
}
return(AttributeEntro);
}
