/// <summary>
/// Must return an array of size 2
/// </summary>
/// <param name="chromosone1"></param>
/// <param name="chromosone2"></param>
/// <returns></returns>
private Individual[] CreateChildren(string chromosone1, string chromosone2)
{
Individual[] newChildren = new Individual[2];
double probabilityOfCrossover = this.RandomNumberGenerator.NextDouble();
double probabilityOfChild1Mutating = this.RandomNumberGenerator.NextDouble();
double probabilityOfChild2Mutating = this.RandomNumberGenerator.NextDouble();
int length = chromosone1.Length;
char [] child1 = new char[length];
char [] child2 = new char[length];
// Position Based Crossover
if (probabilityOfCrossover < this.ProbabilityOfCrossover)
{
List<int> randomPositions = new List<int>();
for (int i = 0; i < this.NumberOfCrossoverPoints; i++)
{
int index = -1;
do
{
index = this.RandomNumberGenerator.Next(0, length);
} while (randomPositions.Contains(index));
randomPositions.Add(index);
}
List<char> remainingCharacters1 = new List<char>(chromosone2.ToCharArray());
List<char> remainingCharacters2 = new List<char>(chromosone1.ToCharArray());
foreach (int point in randomPositions)
{
char c1 = chromosone1[point];
char c2 = chromosone2[point];
child1[point] = c1;
child2[point] = c2;
remainingCharacters1.Remove(c1);
remainingCharacters2.Remove(c2);
}
int j = 0;
for (int i = 0; i < length; i++)
{
if (!randomPositions.Contains(i))
{
child1[i] = remainingCharacters1[j];
child2[i] = remainingCharacters2[j];
j++;
}
}
}
else
{
for (int i = 0; i < length; i++)
{
child1[i] = chromosone1[i];
child2[i] = chromosone2[i];
}
}
// Will Child One Mutate
if (probabilityOfChild1Mutating < this.ProbabilityOfMutation)
{
int oldPosition = this.RandomNumberGenerator.Next(0, length);
int newPosition = -1;
do
{
newPosition = this.RandomNumberGenerator.Next(0, length);
} while (oldPosition == newPosition);
char oldChar = child1[oldPosition];
child1[oldPosition] = child1[newPosition];
child1[newPosition] = oldChar;
}
// Will Child Two Mutate
if (probabilityOfChild2Mutating < this.ProbabilityOfMutation)
{
int oldPosition = this.RandomNumberGenerator.Next(0, length);
int newPosition = -1;
do
{
newPosition = this.RandomNumberGenerator.Next(0, length);
} while (oldPosition == newPosition);
char oldChar = child2[oldPosition];
child2[oldPosition] = child2[newPosition];
child2[newPosition] = oldChar;
}
// Create new children
newChildren[0] = new Individual(this.NGramFrequencies, this.encryptedText, new String(child1));
newChildren[1] = new Individual(this.NGramFrequencies, this.encryptedText, new String(child2));
return newChildren;
}
private int CompareIndividuals(Individual a, Individual b)
{
return -a.Fitness.CompareTo(b.Fitness);
}
