/// <summary>
/// Creates a chromosome.
/// Note: Had a Random inside the method at first, the quick repeat creation of Random caused repeat results.
/// </summary>
/// <param name="selector">A random number generator.</param>
/// <returns>A randomly sequenced chromosome.</returns>
private Chromosome CreateChromosome(Random selector)
{
Chromosome sequence = new Chromosome(selector);
LinkedList <int> usedCities = new LinkedList <int>();
int city = -1;
// Select city to start from.
city = selector.Next(numberOfCites);
sequence.SetStartCity(city);
usedCities.AddLast(city);
// Form path through cities
while (usedCities.Count < numberOfCites)
{
while (usedCities.Contains(city))
{
city = selector.Next(numberOfCites);
}
sequence.AddCityToPath(city);
usedCities.AddLast(city);
}
sequence = checker.ProduceFitnessOfChromosome(sequence);
return(sequence);
}
/// <summary>
/// Evolve a population of chromosomes.
/// Note: Cross mutation 60% of population from worse and mutate a cell for every 10% of range from best fitness.
/// </summary>
/// <param name="population">Population of chromosomes to be evolved.</param>
/// <returns>New evolved population, same size as previous.</returns>
public List <Chromosome> EvolvePopulation(List <Chromosome> population)
{
this.population = population;
Chromosome travelPlan = new Chromosome(randomNumberGenerator);
Chromosome secondTravelPlan = new Chromosome(randomNumberGenerator);
// Ensure newPopulation is empty, If running multiple times.
newPopulation.Clear();
// Find out range of population and workout required value for evolving.
bestFitness = population.ElementAt(0).getFitness();
worseFitness = population.ElementAt(population.Count - 1).getFitness();
rangeOfFitness = worseFitness - bestFitness; // Best will be the lower value as want the shortest distance travelled.
mutationDivValue = rangeOfFitness * mutationFactor;
crossMuttionCutOff = worseFitness - (rangeOfFitness * (1 - crossMutationFactor)); // 1 - factor as want that percentage from the worse fitness.
// Variables needed for cell mutation.
int cellsToMutate = 0;
int preMutationFitness = 0;
// Variable needed for cross-mutation.
LinkedList <int> temp;
int tempIndex = 0;
int preCrossMutationFitnessOfSecond = 0;
for (int count = population.Count - 1; count > -1; count--)
{
travelPlan = population.ElementAt(count);
preMutationFitness = travelPlan.getFitness();
// Determine if cross-mutation or individual cell mutation should be applied.
if (preMutationFitness < crossMuttionCutOff)
{
IndividualCellMutationOption(cellsToMutate, preMutationFitness, travelPlan);
}
else
{
// Cross-mutation option.
// Set up second chromosome to cross mutate with.
secondTravelPlan = population.ElementAt(count - 1);
preCrossMutationFitnessOfSecond = secondTravelPlan.getFitness();
// Set up cross point and get path segment from first chromosome.
temp = travelPlan.CrossMutationRequest();
tempIndex = travelPlan.CrossMutationIndexPoint();
// Apply cross-mutations and get new fitness values.
travelPlan.CrossMutationApplication(secondTravelPlan.CrossMutationRequest(tempIndex), tempIndex);
secondTravelPlan.CrossMutationApplication(temp, tempIndex);
travelPlan = checker.ProduceFitnessOfChromosome(travelPlan);
secondTravelPlan = checker.ProduceFitnessOfChromosome(secondTravelPlan);
// If either or both new fitness is higher than old, revert.
if (travelPlan.getFitness() > preMutationFitness)
{
travelPlan.RevertChromosome();
}
if (secondTravelPlan.getFitness() > preCrossMutationFitnessOfSecond)
{
secondTravelPlan.RevertChromosome();
}
// Add best out of pre and post mutation to new population.
newPopulation.AddLast(travelPlan);
newPopulation.AddLast(secondTravelPlan);
// Adjust count as two chromosomes have changed, otherwise population will grow each evolution.
count--;
}
}
return(newPopulation.OrderBy(Chromosome => Chromosome.getFitness()).ToList());
}
public void ChromosomeTesting(Random randomNumberGenerator)
{
// Create
Chromosome chrom = new Chromosome(randomNumberGenerator);
for (int i = 0; i < 10; i++)
{
if (i == 0)
{
chrom.SetStartCity(i);
}
else
{
chrom.AddCityToPath(i);
}
}
chrom = checker.ProduceFitnessOfChromosome(chrom);
Console.WriteLine("Chromosome create, should see 0 - 9 followed by zero");
Console.WriteLine(chrom.ViewChromosome());
Console.WriteLine("");
// Get first trip cities.
Console.WriteLine("Get cities from first trip");
Console.WriteLine("Start at: " + chrom.TripStartFrom(1) + " end at: " + chrom.TripDestination(1));
Console.WriteLine("");
// Get fourth trip cities.
Console.WriteLine("Get cities from fourth trip");
Console.WriteLine("Start at: " + chrom.TripStartFrom(4) + " end at: " + chrom.TripDestination(4));
Console.WriteLine("");
// Get last trip cities.
Console.WriteLine("Get cities from last trip");
Console.WriteLine("Start at: " + chrom.TripStartFrom(10) + " end at: " + chrom.TripDestination(10));
Console.WriteLine("");
// Single mutation.
chrom.Mutation(1);
chrom = checker.ProduceFitnessOfChromosome(chrom);
Console.WriteLine("Chromosome has undergone a single mutation.");
Console.WriteLine(chrom.ViewChromosome());
Console.WriteLine("");
// Reversion
chrom.RevertChromosome();
Console.WriteLine("Revert Chromosome.");
Console.WriteLine(chrom.ViewChromosome());
Console.WriteLine("");
// Nine mutations. (Watch in debug to see if any mutations are undone)
chrom.Mutation(9);
chrom = checker.ProduceFitnessOfChromosome(chrom);
Console.WriteLine("Chromosome has undergone three mutations.");
Console.WriteLine(chrom.ViewChromosome());
// Make a second chromosome and test cross mutation.
Chromosome chrom2 = new Chromosome(randomNumberGenerator);
for (int i = 0; i < 10; i++)
{
if (i == 0)
{
chrom2.SetStartCity(i);
}
else
{
chrom2.AddCityToPath(i);
}
}
chrom2 = checker.ProduceFitnessOfChromosome(chrom2);
Console.WriteLine("Second Chromosome create to test cross mutation.");
Console.WriteLine(chrom2.ViewChromosome());
Console.WriteLine("");
LinkedList <int> temp = chrom.CrossMutationRequest();
int tempIndex = chrom.CrossMutationIndexPoint();
chrom.CrossMutationApplication(chrom2.CrossMutationRequest(tempIndex), tempIndex);
chrom2.CrossMutationApplication(temp, tempIndex);
chrom = checker.ProduceFitnessOfChromosome(chrom);
chrom2 = checker.ProduceFitnessOfChromosome(chrom2);
Console.WriteLine("Cross mutation check using point: " + chrom.CrossMutationIndexPoint() + " giving: ");
Console.WriteLine(chrom.ViewChromosome());
Console.WriteLine(chrom2.ViewChromosome());
Console.WriteLine("");
// Make a third chromosome and test cross mutation.
Chromosome chrom3 = new Chromosome(randomNumberGenerator);
for (int i = 0; i < 10; i++)
{
if (i == 4)
{
chrom3.SetStartCity(i);
}
else
{
chrom3.AddCityToPath(i);
}
}
chrom3 = checker.ProduceFitnessOfChromosome(chrom3);
Console.WriteLine("Third Chromosome create to test cross mutation with different start/end point.");
Console.WriteLine(chrom3.ViewChromosome());
Console.WriteLine("Second current looks like: " + chrom2.ViewChromosome());
Console.WriteLine("");
temp = chrom2.CrossMutationRequest();
tempIndex = chrom2.CrossMutationIndexPoint();
chrom2.CrossMutationApplication(chrom3.CrossMutationRequest(tempIndex), tempIndex);
chrom3.CrossMutationApplication(temp, tempIndex);
chrom2 = checker.ProduceFitnessOfChromosome(chrom2);
chrom3 = checker.ProduceFitnessOfChromosome(chrom3);
Console.WriteLine("Cross mutation check using point: " + tempIndex + " giving: ");
Console.WriteLine(chrom2.ViewChromosome());
Console.WriteLine(chrom3.ViewChromosome());
Console.WriteLine("");
}
/// <summary>
/// Once all the inputs have been entered, use this to prepare the output of the neuron.
/// </summary>
public void PrepareOutputForInputNeuron()
{
int lowestIndex = 0;
double lowestWeight = inputWeight[0];
ResetAvailabilities();
// Get input with lowest weight.
for (int startIndex = 1; startIndex < inputs.Count(); startIndex++)
{
if (inputWeight[startIndex] < lowestWeight)
{
lowestWeight = inputWeight[startIndex];
lowestIndex = startIndex;
}
}
// Set start/end point of journey.
output.SetStartCity(inputs[lowestIndex]);
inputAvailable[lowestIndex] = false;
// Add the rest of the cities to output.
int secondLowestIndex = -1;
double secondLowestWeight = -1;
while (output.NumberOfCitiesTravelled() < numberOfInputs)
{
for (int index = 0; index < inputs.Count(); index++)
{
// Check second lowest weight has a value.
if (secondLowestWeight == -1 && inputAvailable[index] == true)
{
secondLowestWeight = inputWeight[index];
secondLowestIndex = index;
// Change second lowest weight if lower value found (which is not -1)
}
else if (inputAvailable[index] == true && inputWeight[index] < secondLowestWeight)
{
secondLowestWeight = inputWeight[index];
secondLowestIndex = index;
}
// Found lowest value, end for loop.
if (lowestWeight == secondLowestWeight)
{
index = inputs.Count() + 9001;
}
}
// Update lowest value with new current lowest values
lowestIndex = secondLowestIndex;
lowestWeight = secondLowestWeight;
secondLowestIndex = -1;
secondLowestWeight = -1;
// Add to output
output.AddCityToPath(inputs[lowestIndex]);
inputAvailable[lowestIndex] = false;
}
// With output complete, get it's fitness
output = checker.ProduceFitnessOfChromosome(output);
// Set up Threshold value if needed.
if (setThreshold)
{
threshold = (checker.FitnessOfTwoCities(inputs[0], inputs[1]) * numberOfInputs);
setThreshold = false;
}
}
