/// <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>
/// Initializes a new instance of the <see cref="FuzzyOutput"/> class.
/// </summary>
///
/// <param name="outputVar">A <see cref="LinguisticVariable"/> representing a Fuzzy Inference System's output.</param>
///
internal FuzzyOutput(LinguisticVariable outputVar)
{
// instance of the constraints list
this.outputList = new List <OutputConstraint>(20);
// output linguistic variable
this.outputVar = outputVar;
}
/// <summary>
/// Initializes a new instance of the <see cref="Clause"/> class.
/// </summary>
///
/// <param name="variable">Linguistic variable of the clause. </param>
///
/// <param name="label">Label of the linguistic variable, a fuzzy set used as label into the linguistic variable.</param>
///
/// <exception cref="KeyNotFoundException">The label indicated was not found in the linguistic variable.</exception>
///
public Clause(LinguisticVariable variable, FuzzySet label)
{
// check if label belongs to var.
variable.GetLabel(label.Name);
// initializing attributes
this.label = label;
this.variable = variable;
}
/// <summary>
/// Adds a linguistic variable to the database.
/// </summary>
///
/// <param name="variable">A linguistic variable to add.</param>
///
/// <exception cref="NullReferenceException">The linguistic variable was not initialized.</exception>
/// <exception cref="ArgumentException">The linguistic variable name already exists in the database.</exception>
///
public void AddVariable( LinguisticVariable variable )
{
// checking for existing name
if ( this.variables.ContainsKey( variable.Name ) )
throw new ArgumentException( "The linguistic variable name already exists in the database." );
// adding label
this.variables.Add( variable.Name, variable );
}
/// <summary>
/// Adds a linguistic variable to the database.
/// </summary>
///
/// <param name="variable">A linguistic variable to add.</param>
///
/// <exception cref="NullReferenceException">The linguistic variable was not initialized.</exception>
/// <exception cref="ArgumentException">The linguistic variable name already exists in the database.</exception>
///
public void AddVariable(LinguisticVariable variable)
{
// checking for existing name
if (this.variables.ContainsKey(variable.Name))
{
throw new ArgumentException("The linguistic variable name already exists in the database.");
}
// adding label
this.variables.Add(variable.Name, variable);
}
// Testing basic functionality of linguistic variables
private void runLingVarTestButton_Click(object sender, EventArgs e)
{
ClearDataSeries();
// create a linguistic variable to represent temperature
LinguisticVariable lvTemperature = new LinguisticVariable("Temperature", 0, 80);
// create the linguistic labels (fuzzy sets) that compose the temperature
FuzzySet fsCold = new FuzzySet("Cold", new TrapezoidalFunction(10, 15, TrapezoidalFunction.EdgeType.Right));
FuzzySet fsCool = new FuzzySet("Cool", new TrapezoidalFunction(10, 15, 20, 25));
FuzzySet fsWarm = new FuzzySet("Warm", new TrapezoidalFunction(20, 25, 30, 35));
FuzzySet fsHot = new FuzzySet("Hot", new TrapezoidalFunction(30, 35, TrapezoidalFunction.EdgeType.Left));
// adding labels to the variable
lvTemperature.AddLabel(fsCold);
lvTemperature.AddLabel(fsCool);
lvTemperature.AddLabel(fsWarm);
lvTemperature.AddLabel(fsHot);
// get membership of some points to the cool fuzzy set
double[][,] chartValues = new double[4][,];
for (int i = 0; i < 4; i++)
chartValues[i] = new double[160, 2];
// showing the shape of the linguistic variable - the shape of its labels memberships from start to end
int j = 0;
for (float x = 0; x < 80; x += 0.5f, j++)
{
double y1 = lvTemperature.GetLabelMembership("Cold", x);
double y2 = lvTemperature.GetLabelMembership("Cool", x);
double y3 = lvTemperature.GetLabelMembership("Warm", x);
double y4 = lvTemperature.GetLabelMembership("Hot", x);
chartValues[0][j, 0] = x;
chartValues[0][j, 1] = y1;
chartValues[1][j, 0] = x;
chartValues[1][j, 1] = y2;
chartValues[2][j, 0] = x;
chartValues[2][j, 1] = y3;
chartValues[3][j, 0] = x;
chartValues[3][j, 1] = y4;
}
// plot membership to a chart
chart.UpdateDataSeries("COLD", chartValues[0]);
chart.UpdateDataSeries("COOL", chartValues[1]);
chart.UpdateDataSeries("WARM", chartValues[2]);
chart.UpdateDataSeries("HOT", chartValues[3]);
}
/// <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( ));
}
}
// Hardcode initializing the Fuzzy Inference System
void InitFuzzyEngine()
{
// Linguistic labels (fuzzy sets) that compose the distances
FuzzySet fsNear = new FuzzySet("Near", new TrapezoidalFunction(15, 50, TrapezoidalFunction.EdgeType.Right));
FuzzySet fsMedium = new FuzzySet("Medium", new TrapezoidalFunction(15, 50, 60, 100));
FuzzySet fsFar = new FuzzySet("Far", new TrapezoidalFunction(60, 100, TrapezoidalFunction.EdgeType.Left));
// Right Distance (Input)
LinguisticVariable lvRight = new LinguisticVariable("RightDistance", 0, 120);
lvRight.AddLabel(fsNear);
lvRight.AddLabel(fsMedium);
lvRight.AddLabel(fsFar);
// Left Distance (Input)
LinguisticVariable lvLeft = new LinguisticVariable("LeftDistance", 0, 120);
lvLeft.AddLabel(fsNear);
lvLeft.AddLabel(fsMedium);
lvLeft.AddLabel(fsFar);
// Front Distance (Input)
LinguisticVariable lvFront = new LinguisticVariable("FrontalDistance", 0, 120);
lvFront.AddLabel(fsNear);
lvFront.AddLabel(fsMedium);
lvFront.AddLabel(fsFar);
// Linguistic labels (fuzzy sets) that compose the angle
FuzzySet fsVN = new FuzzySet("VeryNegative", new TrapezoidalFunction(-40, -35, TrapezoidalFunction.EdgeType.Right));
FuzzySet fsN = new FuzzySet("Negative", new TrapezoidalFunction(-40, -35, -25, -20));
FuzzySet fsLN = new FuzzySet("LittleNegative", new TrapezoidalFunction(-25, -20, -10, -5));
FuzzySet fsZero = new FuzzySet("Zero", new TrapezoidalFunction(-10, 5, 5, 10));
FuzzySet fsLP = new FuzzySet("LittlePositive", new TrapezoidalFunction(5, 10, 20, 25));
FuzzySet fsP = new FuzzySet("Positive", new TrapezoidalFunction(20, 25, 35, 40));
FuzzySet fsVP = new FuzzySet("VeryPositive", new TrapezoidalFunction(35, 40, TrapezoidalFunction.EdgeType.Left));
// Angle
LinguisticVariable lvAngle = new LinguisticVariable("Angle", -50, 50);
lvAngle.AddLabel(fsVN);
lvAngle.AddLabel(fsN);
lvAngle.AddLabel(fsLN);
lvAngle.AddLabel(fsZero);
lvAngle.AddLabel(fsLP);
lvAngle.AddLabel(fsP);
lvAngle.AddLabel(fsVP);
// The database
Database fuzzyDB = new Database();
fuzzyDB.AddVariable(lvFront);
fuzzyDB.AddVariable(lvLeft);
fuzzyDB.AddVariable(lvRight);
fuzzyDB.AddVariable(lvAngle);
// Creating the inference system
IS = new InferenceSystem(fuzzyDB, new CentroidDefuzzifier(1000));
// Going Straight
IS.NewRule("Rule 1", "IF FrontalDistance IS Far THEN Angle IS Zero");
// Going Straight (if can go anywhere)
IS.NewRule("Rule 2", "IF FrontalDistance IS Far AND RightDistance IS Far AND LeftDistance IS Far THEN Angle IS Zero");
// Near right wall
IS.NewRule("Rule 3", "IF RightDistance IS Near AND LeftDistance IS Not Near THEN Angle IS LittleNegative");
// Near left wall
IS.NewRule("Rule 4", "IF RightDistance IS Not Near AND LeftDistance IS Near THEN Angle IS LittlePositive");
// Near front wall - room at right
IS.NewRule("Rule 5", "IF RightDistance IS Far AND FrontalDistance IS Near THEN Angle IS Positive");
// Near front wall - room at left
IS.NewRule("Rule 6", "IF LeftDistance IS Far AND FrontalDistance IS Near THEN Angle IS Negative");
// Near front wall - room at both sides - go right
IS.NewRule("Rule 7", "IF RightDistance IS Far AND LeftDistance IS Far AND FrontalDistance IS Near THEN Angle IS Positive");
}
/// <summary>
/// Initializes a new instance of the <see cref="Clause"/> class.
/// </summary>
///
/// <param name="variable">Linguistic variable of the clause. </param>
///
/// <param name="label">Label of the linguistic variable, a fuzzy set used as label into the linguistic variable.</param>
///
/// <exception cref="KeyNotFoundException">The label indicated was not found in the linguistic variable.</exception>
///
public Clause( LinguisticVariable variable, FuzzySet label )
{
// check if label belongs to var.
variable.GetLabel( label.Name );
// initializing attributes
this.label = label;
this.variable = variable;
}
/// <summary>
/// Initializes a new instance of the <see cref="FuzzyOutput"/> class.
/// </summary>
///
/// <param name="outputVar">A <see cref="LinguisticVariable"/> representing a Fuzzy Inference System's output.</param>
///
internal FuzzyOutput( LinguisticVariable outputVar )
{
// instance of the constraints list
this.outputList = new List<OutputConstraint>( 20 );
// output linguistic variable
this.outputVar = outputVar;
}