public static KnapsackConfig FixedSinglePointCrossover(KnapsackConfig sack1, KnapsackConfig sack2, bool isLeft)
{
int[] crossItems = new int[itemsAmount];
if (isLeft)
{
for (var i = 0; i < itemsAmount / 2; i++)
{
crossItems[i] = sack2.valueAt(i);
}
for (var i = itemsAmount / 2; i < itemsAmount; i++)
{
crossItems[i] = sack1.valueAt(i);
}
}
else
{
for (var i = 0; i < itemsAmount / 2; i++)
{
crossItems[i] = sack1.valueAt(i);
}
for (var i = itemsAmount / 2; i < itemsAmount; i++)
{
crossItems[i] = sack2.valueAt(i);
}
}
KnapsackConfig CrossoverResult = new KnapsackConfig(crossItems);
if (!IsValid(CrossoverResult))
{
CrossoverResult = MakeValid(CrossoverResult);
}
return(CrossoverResult);
}
public static KnapsackConfig MutateHalf(KnapsackConfig sack, Random rand)
{
KnapsackConfig mutatedSack = new KnapsackConfig(sack);
int mutationPosition = rand.Next(itemsAmount);
if (rand.Next() % 2 == 0)
{
for (var i = 0; i < itemsAmount / 2; i++)
{
mutatedSack.swapValue(i);
}
}
else
{
for (var i = itemsAmount / 2; i < itemsAmount; i++)
{
mutatedSack.swapValue(i);
}
}
if (!IsValid(mutatedSack))
{
return(MakeValid(mutatedSack));
}
return(mutatedSack);
}
public void MakeIteration()
{
if (GetKnapsackCost(configsPool[0]) == maximalKnapsackCost)
{
return;
}
List <int> positions = new List <int>();
while (positions.Count < mutationPercentage * configsInPoolAmount)
{
positions.Add(rand.Next(configsInPoolAmount));
positions.Distinct();
}
for (int i = 0; i < configsInPoolAmount; i++)
{
configsPool[i] = activeMutation(configsPool[i], rand);
}
KnapsackConfig[] CrossoverPool = new KnapsackConfig[configsInPoolAmount * 2 - 2];//not very well, if i want to customize Crossover ,but works
for (int j = 0; j < configsInPoolAmount - 1; j++)
{
CrossoverPool[j] = activeCrossover(configsPool[j], configsPool[j + 1], true);
CrossoverPool[(CrossoverPool.Length - 1) - j] = activeCrossover(configsPool[j], configsPool[j + 1], false);
}
var tempConfigs = CrossoverPool
.OrderByDescending(config => GetKnapsackCost(config))
.Take(Convert.ToInt32(configsInPoolAmount))
.ToArray();
configsPool = tempConfigs;
var tuningCoeff = 0.01;
updateConfigs(ref currentBestConfigs, tuningCoeff);
updateConfigs(ref bestConfigsAllTime, tuningCoeff);
}
private static KnapsackConfig MakeValid(KnapsackConfig sack)
{
for (var i = 0; i < sack.Length() && !IsValid(sack); i++)
{
sack.setValueToPassive(i);
}
return(sack);
}
private double GetKnapsackCost(KnapsackConfig sack)
{
double count = 0;
for (int i = 0; i < itemsAmount; i++)
{
if (sack.isValueActive(i))
{
count += itemsCosts[i];
}
}
return(count);
}
private void updateConfigs(ref KnapsackConfig[] currentPool, double tuningCoeff)
{
if (currentPool.Length >= configsPool.Length &&
GetKnapsackCost(currentPool[0]) * (1 - tuningCoeff) > GetKnapsackCost(configsPool[0]))
{
for (int i = 0; i < configsInPoolAmount; i++)
{
configsPool[i] = new KnapsackConfig(currentPool[i]);
}
return;
}
currentPool = currentPool
.Concat(configsPool)
.OrderByDescending(config => GetKnapsackCost(config))
.Distinct()
.Take(bestConfigsAmount)
.ToArray();
}
public static KnapsackConfig TwoPointCrossover(KnapsackConfig sack1, KnapsackConfig sack2, bool isLeft)
{
int firstPoint = rand.Next(itemsAmount - 1), secondPoint = rand.Next(firstPoint + 1, itemsAmount);
int[] crossItems = new int[itemsAmount];
if (isLeft)
{
for (var i = 0; i < firstPoint; i++)
{
crossItems[i] = sack1.valueAt(i);
}
for (var i = firstPoint; i < secondPoint; i++)
{
crossItems[i] = sack2.valueAt(i);
}
for (var i = secondPoint; i < itemsAmount; i++)
{
crossItems[i] = sack1.valueAt(i);
}
}
else
{
for (var i = 0; i < firstPoint; i++)
{
crossItems[i] = sack2.valueAt(i);
}
for (var i = firstPoint; i < secondPoint; i++)
{
crossItems[i] = sack1.valueAt(i);
}
for (var i = secondPoint; i < itemsAmount; i++)
{
crossItems[i] = sack2.valueAt(i);
}
}
KnapsackConfig sack = new KnapsackConfig(crossItems);
if (!IsValid(sack))
{
return(MakeValid(sack));
}
return(sack);
}
private static bool IsValid(KnapsackConfig config)
{
double[] summ = new double[dimensions];
for (var i = 0; i < itemsAmount; i++)
{
if (config.isValueActive(i))
{
for (var j = 0; j < dimensions; j++)
{
summ[j] += itemsSet[i, j];
if (summ[j] > restrictions[j])
{
return(false);
}
}
}
//Amount of items is much bigger than number of dimensions, so we can do checks on every turn.
}
return(true);
}
private KnapsackConfig FirstApproachGenerate()
{
KnapsackConfig result = new KnapsackConfig(itemsAmount);
for (var i = 0; i < itemsAmount; i++)
{
result.setValueToActive(i);
}
Random rand = new Random();
while (!IsValid(result))
{
int positionNumber = rand.Next(itemsAmount);
while (!result.isValueActive(positionNumber))
{
positionNumber = rand.Next(itemsAmount);
}
result.setValueToPassive(positionNumber);
}
return(result);
}
public static KnapsackConfig SinglePointMutation(KnapsackConfig sack, Random rand)
{
KnapsackConfig mutatedSack = new KnapsackConfig(sack);//copy constructor
int mutationPosition = rand.Next(itemsAmount);
var count = 0;
var iterationsToResque = 100000;
while (mutatedSack.Equals(sack) && count < iterationsToResque)//TODO - not mutate empty sack
{
mutatedSack.swapValue(mutationPosition);
if (!IsValid(mutatedSack))//somehow unrealistic
{
mutatedSack.swapValue(mutationPosition);
mutationPosition = rand.Next(itemsAmount);
}
count++;
}
if (count == iterationsToResque)
{
return(MakeValid(mutatedSack));
}
return(mutatedSack);
}