public double GetKnapsackFitness(Knapsack knapsack)
{
var totalWeight = (double)knapsack.GetTotalWeight(Packages);
var totalValue = (double)knapsack.GetTotalValue(Packages);
var fitness = 0d;
if (totalWeight <= _maxKnapsackWeight)
{
return(totalValue);
}
switch (PenaltyMethod)
{
case PenaltyMethod.Static:
fitness = 0;
break;
case PenaltyMethod.Adaptive:
double penalty = 1 / (totalWeight - _maxKnapsackWeight);
fitness = totalValue * penalty - 1;
break;
}
return(fitness);
}
public Knapsack Crossover(Knapsack parent1, Knapsack parent2)
{
var random = RandomGenerator.Random.NextDouble();
var child = new Knapsack(_knapsackCapacity, _maxKnapsackWeight);
if (random <= CrossoverRate)
{
var crossoverPoint = RandomGenerator.Random.Next(1, 20);
var endPoint = _knapsackCapacity - crossoverPoint;
child.BitString = $"{parent1.BitString.Substring(0, crossoverPoint)}{parent2.BitString.Substring(crossoverPoint, endPoint)}";
return(child);
}
return(GetKnapsackFitness(parent1) > GetKnapsackFitness(parent2) ? parent1 : parent2);
}
public Knapsack Mutate(Knapsack candidate)
{
var bitString = "";
foreach (var bit in candidate.BitString)
{
var random = RandomGenerator.Random.NextDouble();
if (random <= MutationRate)
{
bitString += bit == '1' ? '0' : '1';
}
else
{
bitString += bit;
}
}
candidate.BitString = bitString;
return(candidate);
}
