/// <summary>
/// Executes the fuzzy inference, obtaining the <see cref="FuzzyOutput"/> of the system for the required
/// <see cref="LinguisticVariable"/>.
/// </summary>
///
/// <param name="variableName">Name of the <see cref="LinguisticVariable"/> to evaluate.</param>
///
/// <returns>A <see cref="FuzzyOutput"/> containing the fuzzy output of the system for the
/// <see cref="LinguisticVariable"/> specified in <paramref name="variableName"/>.</returns>
///
/// <exception cref="KeyNotFoundException">The variable indicated was not found in the database.</exception>
///
public FuzzyOutput ExecuteInference(string variableName)
{
// gets the variable
LinguisticVariable lingVar = database.GetVariable(variableName);
// object to store the fuzzy output
FuzzyOutput fuzzyOutput = new FuzzyOutput(lingVar);
// select only rules with the variable as output
Rule[] rules = rulebase.GetRules( );
foreach (Rule r in rules)
{
if (r.Output.Variable.Name == variableName)
{
string labelName = r.Output.Label.Name;
float firingStrength = r.EvaluateFiringStrength( );
if (firingStrength > 0)
{
fuzzyOutput.AddOutput(labelName, firingStrength);
}
}
}
// returns the fuzzy output obtained
return(fuzzyOutput);
}
/// <summary>
/// Centroid method to obtain the numerical representation of a fuzzy output. The numerical
/// value will be the center of the shape formed by the several fuzzy labels with their
/// constraints.
/// </summary>
///
/// <param name="fuzzyOutput">A <see cref="FuzzyOutput"/> containing the output of several
/// rules of a Fuzzy Inference System.</param>
/// <param name="normOperator">A <see cref="INorm"/> operator to be used when constraining
/// the label to the firing strength.</param>
///
/// <returns>The numerical representation of the fuzzy output.</returns>
///
/// <exception cref="Exception">The numerical output is unavaliable. All memberships are zero.</exception>
///
public float Defuzzify(FuzzyOutput fuzzyOutput, INorm normOperator)
{
// results and accumulators
float weightSum = 0, membershipSum = 0;
// speech universe
float start = fuzzyOutput.OutputVariable.Start;
float end = fuzzyOutput.OutputVariable.End;
// increment
float increment = (end - start) / this.intervals;
// running through the speech universe and evaluating the labels at each point
for (float x = start; x < end; x += increment)
{
// we must evaluate x membership to each one of the output labels
foreach (FuzzyOutput.OutputConstraint oc in fuzzyOutput.OutputList)
{
// getting the membership for X and constraining it with the firing strength
float membership = fuzzyOutput.OutputVariable.GetLabelMembership(oc.Label, x);
float constrainedMembership = normOperator.Evaluate(membership, oc.FiringStrength);
weightSum += x * constrainedMembership;
membershipSum += constrainedMembership;
}
}
// if no membership was found, then the membershipSum is zero and the numerical output is unknown.
if (membershipSum == 0)
{
throw new Exception("The numerical output in unavaliable. All memberships are zero.");
}
return(weightSum / membershipSum);
}
/// <summary>
/// Executes the fuzzy inference, obtaining a numerical output for a choosen output
/// linguistic variable.
/// </summary>
///
/// <param name="variableName">Name of the <see cref="LinguisticVariable"/> to evaluate.</param>
///
/// <returns>The numerical output of the Fuzzy Inference System for the choosen variable.</returns>
///
/// <exception cref="KeyNotFoundException">The variable indicated was not found in the database.</exception>
///
public float Evaluate(string variableName)
{
// call the defuzzification on fuzzy output
FuzzyOutput fuzzyOutput = ExecuteInference(variableName);
float res = defuzzifier.Defuzzify(fuzzyOutput, normOperator);
return(res);
}
