/// <summary>
/// Adds a linguistic label to the variable.
/// </summary>
///
/// <param name="label">A <see cref="FuzzySet"/> that will be a linguistic label of the linguistic variable.</param>
///
/// <remarks>Linguistic labels are fuzzy sets (<see cref="FuzzySet"/>). Each
/// label of the variable must have a unique name. The range of the label
/// (left and right limits) cannot be greater than
/// the linguistic variable range (start/end).</remarks>
///
/// <exception cref="NullReferenceException">The fuzzy set was not initialized.</exception>
/// <exception cref="ArgumentException">The linguistic label name already exists in the linguistic variable.</exception>
/// <exception cref="ArgumentException">The left limit of the fuzzy set can not be lower than the linguistic variable's starting point.</exception>
/// <exception cref="ArgumentException">"The right limit of the fuzzy set can not be greater than the linguistic variable's ending point."</exception>
///
public void AddLabel(FuzzySet label)
{
// checking for existing name
if (this.labels.ContainsKey(label.Name))
{
throw new ArgumentException("The linguistic label name already exists in the linguistic variable.");
}
// checking ranges
if (label.LeftLimit < this.start)
{
throw new ArgumentException("The left limit of the fuzzy set can not be lower than the linguistic variable's starting point.");
}
if (label.RightLimit > this.end)
{
throw new ArgumentException("The right limit of the fuzzy set can not be greater than the linguistic variable's ending point.");
}
// adding label
this.labels.Add(label.Name, label);
}
/// <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( ));
}
}
/// <summary>
/// Calculate the membership of a given value to a given label. Used to evaluate linguistics clauses like
/// "X IS A", where X is a value and A is a linguistic label.
/// </summary>
///
/// <param name="labelName">Label (fuzzy set) to evaluate value's membership.</param>
/// <param name="value">Value which label's membership will to be calculated.</param>
///
/// <returns>Degree of membership [0..1] of the value to the label (fuzzy set).</returns>
///
/// <exception cref="KeyNotFoundException">The label indicated in labelName was not found in the linguistic variable.</exception>
///
public float GetLabelMembership(string labelName, float value)
{
FuzzySet fs = labels[labelName];
return(fs.GetMembership(value));
}