// https://en.wikipedia.org/wiki/Coefficient_of_variation
public static double WeightUsingCoefficientOfVariation(IFeatureCollectionWrapper <FeatureBase> featureValues)
{
var features = featureValues.Where(feature => !feature.FeatureValue.Equals(-1.0));
if (!features.Any() || features.Count() < 2)
{
return(0);
}
var stdDev = features.StandardDeviation(feature => feature.FeatureValue);
if (stdDev.Equals(0))
{
return(1);
} // /Math.Sqrt(features.Count()); }
var average = features.Average(feature => feature.FeatureValue);
if (stdDev.CompareTo(average) > 0)
{
return(0);
} //average / stdDev; }
return(stdDev / average);
}
public static double WeightUsingVarianceAndStandarDeviation(IFeatureCollectionWrapper <FeatureBase> featureValues)
{
var features = featureValues.Where(feature => !feature.FeatureValue.Equals(-1.0));
if (!features.Any() || features.Count() < 2)
{
return(0);
}
//if (featureValues.Count() < 2) { return 1; }
var stdDev = features.StandardDeviation(feature => feature.FeatureValue);
if (stdDev.Equals(0))
{
return(1 / Math.Sqrt(features.Count()));
}
var variance = features.Variance(feature => feature.FeatureValue);
if (stdDev.CompareTo(variance) > 0)
{
return(1 - (stdDev));
}
return(1 - (stdDev / variance));
}
public static double WeightUsingStandarDeviation(IFeatureCollectionWrapper <FeatureBase> featureValues)
{
var features = featureValues.Where(feature => !feature.FeatureValue.Equals(-1.0));
if (!features.Any() || features.Count() < 2)
{
return(0);
}
//if (featureValues.Count() < 2) { return 1; }
var stdDev = features.StandardDeviation(feature => feature.FeatureValue);
// if(stdDev.Equals(0)) { return 1;}
return(1 / Math.Sqrt(1 + stdDev));
}
public static double WeightUsingNormEntropy(IFeatureCollectionWrapper <FeatureBase> featureValues)
{
var features = featureValues.Where(feature => !feature.FeatureValue.Equals(-1.0));
if (!features.Any() || features.Count() == 1)
{
return(0);
}
var values = (from i in featureValues
group i by i.FeatureValue
into grp
orderby grp.Count() descending
select grp);
//if (featureValues.Count() == 1) { return 1; }
int classes;
var entropyValue = Entropy.Calculate(features.Select(feature => feature.FeatureValue), out classes);
if (entropyValue.Equals(0))
{
return(1); //(double)1 / Math.Sqrt(classes);
}
var result = 1 - entropyValue / Math.Log(classes);
if (result.Equals(0))
{
return(result);
}
//return WeightUsingCoefficientOfVariation(featureValues);
if (values.Count() < Math.Sqrt(classes))
{
var coeffOfVar = WeightUsingCoefficientOfVariation(featureValues);
if (!coeffOfVar.Equals(0))
{
return(coeffOfVar);
}
//return coeffOfVar;
}
return(result);
}
public static double FeatureMetricAverage(IFeatureCollectionWrapper <FeatureBase> featureValues)
{
var features = featureValues.Where(feature => !feature.FeatureValue.Equals(-1.0)).ToArray();
return(!features.Any()? 0 : features.Average(feature => feature.FeatureValue));
}