double SymmetricUncertaintyCalculator::calculateUncertainty(const DataFrame& df1,
int factorIndex1, const DataFrame& df2, int factorIndex2)
{
assert(df1.isNominal(factorIndex1));
assert(df2.isNominal(factorIndex2));
double hy = _calculateEntropy(df1, factorIndex1);
double hyx = _calculateConditionalEntropy(df1, factorIndex1, df2, factorIndex2);
double gain = hy - hyx;
double hx = _calculateEntropy(df2, factorIndex2);
if (hy + hx == 0.0)
{
return 1.0;
}
double result = 2.0 * (gain / (hy + hx));
return result;
}
double InformationGainCalculator::calculateInformationGain(const DataFrame& df1,
int factorIndex1, const DataFrame& df2, int factorIndex2)
{
assert(df1.isNominal(factorIndex1));
assert(df2.isNominal(factorIndex2));
double hy = _calculateEntropy(df1, factorIndex1);
double hyx = _calculateConditionalEntropy(df1, factorIndex1, df2, factorIndex2);
double gain = hy - hyx;
return gain;
}