private IEnumerable <Chromosome <T> > DoCrossover(Population <T> generationPopulation,
SecureRandom random, int childCount)
{
const int ParentCount = 2;
var RouletteSelection = (uint)Math.Ceiling((double)generationPopulation.Chromosomes.Count * 0.05);
var crossovers = new ConcurrentBag <Chromosome <T> >();
var tasks = new Task[this.Parameters.TaskCount];
for (var c = 0; c < this.Parameters.TaskCount; c++)
{
tasks[c] = Task.Factory.StartNew(() =>
{
do
{
var parents = new List <Chromosome <T> >();
var indexes = random.GetInt32Values(RouletteSelection,
new Range <int>(0, generationPopulation.Chromosomes.Count), ValueGeneration.UniqueValuesOnly);
for (var i = 0; i < ParentCount; i++)
{
var parent = (from chromosome in
(from index in indexes
select generationPopulation.Chromosomes[index])
orderby chromosome.Fitness descending
select chromosome).Take(1).First();
parents.Add(parent);
}
var children = random.NextDouble() < this.Parameters.CrossoverProbability ?
this.Parameters.Crossover(parents.AsReadOnly()) :
new List <T>(from parent in parents
select this.Parameters.Copy(parent.Value)).AsReadOnly();
foreach (var child in children)
{
var mutatedChild = this.Parameters.Mutator(child);
if (mutatedChild != null)
{
crossovers.Add(new Chromosome <T>(
mutatedChild, this.Parameters.FitnessEvaluator(mutatedChild)));
}
}
} while (crossovers.Count < childCount);
});
}
Task.WaitAll(tasks);
return(crossovers.AsEnumerable());
}
public void GetInt32ValuesUniqueValuesOnlyButElementNumberIsTooBig()
{
using (var random = new SecureRandom())
{
random.GetInt32Values((uint)int.MaxValue + 10u, ValueGeneration.UniqueValuesOnly);
}
}
public void GetInt32ValuesUniqueValuesOnly()
{
var generator = new MockRandomNumberGeneratorForGetInt32Values(ValueGeneration.UniqueValuesOnly);
using (var random = new SecureRandom(generator))
{
var elements = random.GetInt32Values(
8, ValueGeneration.UniqueValuesOnly);
Assert.AreEqual(8, elements.Length);
for (var i = 0; i < elements.Length; i++)
{
var element = elements[i];
Assert.IsTrue(element >= int.MinValue);
Assert.IsTrue(element <= int.MaxValue);
}
Assert.AreEqual(elements.Length, new HashSet<int>(elements).Count);
Assert.AreEqual(9, generator.MethodCallCount);
}
}
public void GetInt32ValuesDuplicatesAllowed()
{
var generator = new MockRandomNumberGeneratorForGetInt32Values(ValueGeneration.DuplicatesAllowed);
using (var random = new SecureRandom(generator))
{
var elements = random.GetInt32Values(8, ValueGeneration.DuplicatesAllowed);
Assert.AreEqual(8, elements.Length);
for (var i = 0; i < elements.Length; i++)
{
var element = elements[i];
Assert.IsTrue(element >= int.MinValue);
Assert.IsTrue(element < int.MaxValue);
}
Assert.AreEqual(8, generator.MethodCallCount);
}
}
public void GetInt32ValuesAfterDisposing()
{
SecureRandom random = null;
using (random = new SecureRandom())
{
}
random.GetInt32Values(1, ValueGeneration.DuplicatesAllowed);
}