/**
* <summary> The calculateMetric method takes an {@link Instance} and a String as inputs. It multiplies Matrix Wi with Vector xi
* then calculates the dot product of it with xi. Then, again it finds the dot product of wi and xi and returns the summation with w0i.</summary>
*
* <param name="instance">{@link Instance} input.</param>
* <param name="ci"> String input.</param>
* <returns>The result of Wi.multiplyWithVectorFromLeft(xi).dotProduct(xi) + wi.dotProduct(xi) + w0i.</returns>
*/
protected override double CalculateMetric(Instance.Instance instance, string ci)
{
var xi = instance.ToVector();
var Wi = _W[ci];
var wi = w[ci];
var w0i = w0[ci];
return(Wi.MultiplyWithVectorFromLeft(xi).DotProduct(xi) + wi.DotProduct(xi) + w0i);
}
/**
* <summary> Calculates Mahalanobis distance between two instances. (x^(1) - x^(2)) S (x^(1) - x^(2))^T</summary>
*
* <param name="instance1">First instance.</param>
* <param name="instance2">Second instance.</param>
* <returns>Mahalanobis distance between two instances.</returns>
*/
public double Distance(Instance.Instance instance1, Instance.Instance instance2)
{
var v1 = instance1.ToVector();
var v2 = instance2.ToVector();
v1.Subtract(v2);
var v3 = _covarianceInverse.MultiplyWithVectorFromLeft(v1);
return(v3.DotProduct(v1));
}
/**
* <summary> The createInputVector method takes an {@link Instance} as an input. It converts given Instance to the {@link java.util.Vector}
* and insert 1.0 to the first element.</summary>
*
* <param name="instance">Instance to insert 1.0.</param>
*/
protected void CreateInputVector(Instance.Instance instance)
{
x = instance.ToVector();
x.Insert(0, 1.0);
}