private double CalculateFitness(NGramFrequencies nGramFrequencies, string encryptedText, string chromosone)
{
double currentFitness = 0;
string decryptedText = SubstitutionCipher.DecryptText(encryptedText, chromosone);
MemoryStream stream = new MemoryStream(ASCIIEncoding.Default.GetBytes(decryptedText));
NGramFrequencies decryptedTextFrequencies = NGramFrequencies.Analyse(new StreamReader(stream), nGramFrequencies.Length);
foreach (string ngram in decryptedTextFrequencies)
{
double trainedFrequency = nGramFrequencies.FrequencyOf(ngram);
if (trainedFrequency != 0)
{
currentFitness += decryptedTextFrequencies.FrequencyOf(ngram) * Math.Log(trainedFrequency, FITNESS_LOGARITHM_BASE);
}
}
return currentFitness;
}
public Environment(string trainingFilePath, string plainText, string encryptedText,
int numberOfGenerations, int populationSize,
double percentageOfElitism, int tournamentSize,
double tournamentWinnerProbability, double probabilityOfCrossover,
int numberOfCrossoverPoints, double probabilityOfMutation)
{
this.nGramFrequencies = NGramFrequencies.Analyse(new StreamReader(trainingFilePath), NGRAM_LENGTH);
this.trainedLetterFrequencies = LetterFrequencies.Analyse(new StreamReader(trainingFilePath));
this.cipherLetterFrequencies = LetterFrequencies.Analyse(new StreamReader(new MemoryStream(ASCIIEncoding.Default.GetBytes(encryptedText))));
this.randomNumberGenerator = new Random(1337);
this.decryptedText = plainText.Trim().ToUpper();
this.encryptedText = encryptedText.Trim().ToUpper();
this.numberOfGenerations = numberOfGenerations;
this.populationSize = populationSize;
this.percentageOfElitism = percentageOfElitism;
this.tournamentSize = tournamentSize;
this.tournamentWinnerProbability = tournamentWinnerProbability;
this.probabilityOfCrossover = probabilityOfCrossover;
this.numberOfCrossoverPoints = numberOfCrossoverPoints;
this.probabilityOfMutation = probabilityOfMutation;
this.population = new List<Individual>();
this.currentGeneration = 0;
CreateInitialPopulation();
}
public Individual(NGramFrequencies nGramFrequencies, string encryptedText, string chromosone)
{
this.chromosone = chromosone;
this.fitness = CalculateFitness(nGramFrequencies, encryptedText, chromosone);
}