private Person cross(Person parent1, Person parent2)
{
int nbSeq = (int)(_nbNote * new Random().NextDouble());
int[] aNote = new int[_nbNote];
Person newPerson = new Person(_nbNote);
for (int i = 0; i < _nbNote; i++) {
if (i > nbSeq) {
aNote[i] = parent2.notes[i];
}
else {
aNote[i] = parent1.notes[i];
}
}
newPerson.notes = aNote;
if (parent1.fitness >= parent2.fitness) {
newPerson.instrument = parent1.instrument;
}
else {
newPerson.instrument = parent2.instrument;
}
return newPerson;
}
public Population()
{
random = new Random();
_mutationRate = 1 / _nbNote;
_persons = new Person[_nbPerson];
for (int i = 0; i < _nbPerson; i++) {
_persons[i] = new Person(_nbNote, random.Next(1,129));
_persons[i].generateRandomNotes(random);
}
}
private Person mutation(Person person)
{
for (int i = 0; i < _nbNote; i++) {
if (random.NextDouble() <= _mutationRate) {
person.notes[i] = random.Next(0,127);
}
}
return person;
}
//survive if sum of fitness >= survivalRate
private Person selectBest()
{
int sumFitness = 0;
Person best = new Person(_nbNote);
for (int i = 0; i < _nbPerson; i++) {
sumFitness += _persons[i].fitness;
if (_persons[i].fitness > best.fitness) {
best = _persons[i];
best.fitness = 0;
}
}
if (sumFitness / _nbPerson < _survivalRate) {
best = null;
}
return best;
}
public void newGeneration()
{
int i = 0;
Person bestPerson = selectBest();
Person[] newPopulation = new Person[_nbPerson];
if (bestPerson != null) {
Person person = new Person(_nbNote);
person = bestPerson;
person.fitness = 0;
newPopulation[i] = person;
i++;
}
for (; i < _nbPerson; i++) {
Person person = selection();
if (random.NextDouble() < _crossoverRate) {
Person crossPerson = selection();
person = cross(person, crossPerson);
}
person = mutation(person);
person.fitness = 0;
newPopulation[i] = person;
}
_persons = newPopulation;
}
