public string DecodeExpression(GPNode treeExpression, int langOption)
{
//Prepare chromoseme for evaluation
var tokens = treeExpression.ToList();
int countT = tokens.Count;
//Stack fr evaluation
Stack <string> expression = new Stack <string>();
for (int i = countT - 1; i >= 0; i--)
{
if (tokens[i] >= 1000 && tokens[i] < 2000)
{
string varaiable = terminals[tokens[i] - 1000].Name;
expression.Push(varaiable);
}
else
{
//prepare function arguments for evaluation
int count = functions[tokens[i] - 2000].Aritry;
string function = "";
if (langOption == 1)
{
function = functions[tokens[i] - 2000].MathematicaDefinition;
}
else if (langOption == 2)
{
function = functions[tokens[i] - 2000].ExcelDefinition;
}
else
{
function = functions[tokens[i] - 2000].Definition;
}
for (int j = 1; j <= count; j++)
{
string oldStr = "x" + (j).ToString();
string newStr = expression.Pop();
function = function.Replace(oldStr, newStr);
}
//Izracunavanje rezultata
expression.Push("(" + function + ")");
}
}
// return the only value from stack
Debug.Assert(expression.Count == 1);
// return arguments.Pop();
return(expression.Pop());
}
/// <summary>
/// Converts GPNode in to expression
/// </summary>
/// <param name="treeExpression">chromosome in S-expression</param>
/// <param name="rowIndex"> current row to evaluate choromosme</param>
/// <param name="btrainingData">whether is training or testing data</param>
/// <returns></returns>
public double Evaluate(GPNode treeExpression, int rowIndex, bool btrainingData = true)
{
//get the array from tree nodes
treeExpression.ToList(_tokens.Value);
var tokens = _tokens.Value;
//count all tokens
int countT = tokens.Count();
//get terminal for specific position
double[] terminalRow = Globals.GetTerminalRow(rowIndex, btrainingData);
//Stack for evaluation
Stack <double> arguments = _arguments.Value;//new Stack<double>();
//the maximum aritry is 4
// double[] val = new double[5];
for (int i = countT - 1; i >= 0; i--)
{
//skip invalid tokens
if (tokens[i] < 1000)
{
continue;
}
// Put terminal in to Stack for leter function evaluation
if (tokens[i] >= 1000 && tokens[i] < 2000)
{
arguments.Push(terminalRow[tokens[i] - 1000]);
//reset node
tokens[i] = 0;
}
else
{
//create real index value
int ind = tokens[i] - 2000;
//make current token invalid
//or reset token position
tokens[i] = 0;
//prepare function arguments for evaluation
int count = functions[ind].Aritry;
//Extract variables
for (int j = 0; j < count; j++)
{
var num = arguments.Pop();
if (double.IsNaN(num) || double.IsInfinity(num))
{
ResetTokensList(tokens, arguments, i);
return(double.NaN);
}
_args.Value[j] = num;
}
double result = Evaluate(functions[ind], _args.Value);
_args.Value[0] = 0;
_args.Value[1] = 0;
_args.Value[2] = 0;
_args.Value[3] = 0;
_args.Value[4] = 0;
//check if number is valid
if (double.IsNaN(result) || double.IsInfinity(result))
{
//reset the rest of elements in the list
ResetTokensList(tokens, arguments, i);
return(double.NaN);
}
//inser subresult in to stack
arguments.Push(result);
}
}
// return the only value from stack
Debug.Assert(arguments.Count == 1);
return(arguments.Pop());
}
