/// <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>
/// Converts the Fuzzy Rule to RPN (Reverse Polish Notation). For debug proposes, the string representation of the
/// RPN expression can be acessed by calling <see cref="GetRPNExpression"/> method.
/// </summary>
///
private void ParseRule( )
{
// flag to incicate we are on consequent state
bool consequent = false;
// tokens like IF and THEN will be searched always in upper case
string upRule = rule.ToUpper( );
// the rule must start with IF, and must have a THEN somewhere
if (!upRule.StartsWith("IF"))
{
throw new ArgumentException("A Fuzzy Rule must start with an IF statement.");
}
if (upRule.IndexOf("THEN") < 0)
{
throw new ArgumentException("Missing the consequent (THEN) statement.");
}
// building a list with all the expression (rule) string tokens
string spacedRule = rule.Replace("(", " ( ").Replace(")", " ) ");
// getting the tokens list
string[] tokensList = GetRuleTokens(spacedRule);
// stack to convert to RPN
Stack <string> s = new Stack <string>( );
// storing the last token
string lastToken = "IF";
// linguistic var read, used to build clause
LinguisticVariable lingVar = null;
// verifying each token
for (int i = 0; i < tokensList.Length; i++)
{
// removing spaces
string token = tokensList[i].Trim( );
// getting upper case
string upToken = token.ToUpper( );
// ignoring these tokens
if (upToken == "" || upToken == "IF")
{
continue;
}
// if the THEN is found, the rule is now on consequent
if (upToken == "THEN")
{
lastToken = upToken;
consequent = true;
continue;
}
// if we got a linguistic variable, an IS statement and a label is needed
if (lastToken == "VAR")
{
if (upToken == "IS")
{
lastToken = upToken;
}
else
{
throw new ArgumentException("An IS statement is expected after a linguistic variable.");
}
}
// if we got an IS statement, a label must follow it
else if (lastToken == "IS")
{
try
{
FuzzySet fs = lingVar.GetLabel(token);
Clause c = new Clause(lingVar, fs);
if (consequent)
{
output = c;
}
else
{
rpnTokenList.Add(c);
}
lastToken = "LAB";
}
catch (KeyNotFoundException)
{
throw new ArgumentException("Linguistic label " + token + " was not found on the variable " + lingVar.Name + ".");
}
}
// not VAR and not IS statement
else
{
// openning new scope
if (upToken == "(")
{
// if we are on consequent, only variables can be found
if (consequent)
{
throw new ArgumentException("Linguistic variable expected after a THEN statement.");
}
// if its a (, just push it
s.Push(upToken);
lastToken = upToken;
}
// operators
else if (upToken == "AND" || upToken == "OR" || unaryOperators.IndexOf(upToken) >= 0)
{
// if we are on consequent, only variables can be found
if (consequent)
{
throw new ArgumentException("Linguistic variable expected after a THEN statement.");
}
// pop all the higher priority operators until the stack is empty
while ((s.Count > 0) && (Priority(s.Peek( )) > Priority(upToken)))
{
rpnTokenList.Add(s.Pop( ));
}
// pushing the operator
s.Push(upToken);
lastToken = upToken;
}
// closing the scope
else if (upToken == ")")
{
// if we are on consequent, only variables can be found
if (consequent)
{
throw new ArgumentException("Linguistic variable expected after a THEN statement.");
}
// if there is nothing on the stack, an oppening parenthesis is missing.
if (s.Count == 0)
{
throw new ArgumentException("Openning parenthesis missing.");
}
// pop the tokens and copy to output until openning is found
while (s.Peek( ) != "(")
{
rpnTokenList.Add(s.Pop( ));
if (s.Count == 0)
{
throw new ArgumentException("Openning parenthesis missing.");
}
}
s.Pop( );
// saving last token...
lastToken = upToken;
}
// finally, the token is a variable
else
{
// find the variable
try
{
lingVar = database.GetVariable(token);
lastToken = "VAR";
}
catch (KeyNotFoundException)
{
throw new ArgumentException("Linguistic variable " + token + " was not found on the database.");
}
}
}
}
// popping all operators left in stack
while (s.Count > 0)
{
rpnTokenList.Add(s.Pop( ));
}
}