/// <summary>
/// Breeds two parent path individuals to create an offspring path individual.
/// </summary>
/// <param name="firstParent">The first path individual to breed with second path individual .</param>
/// <param name="secondParent">The second path individual to breed with first path individual.</param>
/// <returns>Offspring path individual of specified parents.</returns>
public static PathGraph Crossover(PathGraph firstParent, PathGraph secondParent)
{
int CircuitLength = Input.Size + 1;
// Create new child path
PathGraph ChildPath = new PathGraph(CircuitLength, Input);
ChildPath[0] = Input[0];
ChildPath[CircuitLength - 1] = Input[0];
// Get random start and end indices positions for firstParent
int StartPos = ThreadSafeRandom.CurrentThreadsRandom.Next(1, CircuitLength - 1);
int EndPos = ThreadSafeRandom.CurrentThreadsRandom.Next(1, CircuitLength - 1) + ThreadSafeRandom.CurrentThreadsRandom.Next(1, CircuitLength - 1);
// Loop and add the sub tour from firstParent to our child
for (int i = 1; i < CircuitLength - 1; ++i)
{
// If our start position is less than the end position
if (StartPos < EndPos && i > StartPos && i < EndPos)
{
ChildPath[i] = firstParent[i];
}
// If our start position is larger
else if (StartPos > EndPos)
{
//if (!(i < StartPos && i > EndPos))
if (i >= StartPos || i <= EndPos)
{
ChildPath[i] = firstParent[i];
}
}
}
// Loop through parent2's path
for (int i = 1; i < CircuitLength - 1; ++i)
{
// If child doesn't have the city add it
if (!ChildPath.Contains(secondParent[i]))
{
// Loop to find a spare position in the child's tour
for (int j = 1; j < CircuitLength - 1; ++j)
{
// Spare position found, add city
if (ChildPath[j] == null)
{
ChildPath[j] = secondParent[i];
break;
}
}
}
}
return(ChildPath);
}
private static PathGraph DefaultCrossover(PathGraph firstParent, PathGraph secondParent)
{
int CircuitLength = Input.Size + 1;
// Create new child path
PathGraph ChildPath = new PathGraph(CircuitLength, Input);
ChildPath[0] = Input[0];
ChildPath[CircuitLength - 1] = Input[0];
// Get random start and end indices positions for firstParent
int StartPos = ThreadSafeRandom.CurrentThreadsRandom.Next(1, CircuitLength - 1);
int EndPos = ThreadSafeRandom.CurrentThreadsRandom.Next(1, CircuitLength - 1) + ThreadSafeRandom.CurrentThreadsRandom.Next(1, CircuitLength - 1);
// Iterate firstParent to add subset to the child
for (int i = 1; i < CircuitLength - 1; ++i)
{
if (StartPos < EndPos && i > StartPos && i < EndPos)
{
ChildPath[i] = firstParent[i];
}
else if (StartPos > EndPos)
{
if (i >= StartPos || i <= EndPos)
{
ChildPath[i] = firstParent[i];
}
}
}
// Iterate secondParent's vertices to fill the remaining vertices
for (int i = 1; i < CircuitLength - 1; ++i)
{
// Add vertex if child does not contain it already
if (!ChildPath.Contains(secondParent[i]))
{
// Find an empty position in child
for (int j = 1; j < CircuitLength - 1; ++j)
{
// Add vertex to empty spot
if (ChildPath[j] == null)
{
ChildPath[j] = secondParent[i];
break;
}
}
}
}
return(ChildPath);
}
