private BestSoFar LocalSearch(Ant bestAnt)
{
var iterationBest = new BestSoFar(this.startingNode.NodeId, this.endNodeId)
{
Route = bestAnt.Route,
RouteDistance = bestAnt.RouteDistance
};
//if (iterationBest.Route.Count > 4)
//{
// for (var i = 0; i < this.iterations; i++)
// {
// var children = FindChildren(iterationBest);
// var bestChild = children.OrderBy(x => x.RouteDistance).FirstOrDefault();
// if (bestChild.RouteDistance > iterationBest.RouteDistance)
// {
// break;
// }
// iterationBest = bestChild;
// }
//}
return(iterationBest);
}
private List <BestSoFar> FindChildren(BestSoFar bestRoute)
{
var children = new List <BestSoFar>();
int ceiling = this.endNodeId == null ? (bestRoute.Route.Count - 2) / 2 : (bestRoute.Route.Count - 3) / 2;
for (var i = 0; i < ceiling; i++)
{
var index = 1 + i * 2;
var route = bestRoute.Route.ToList();
var distance = bestRoute.RouteDistance;
distance -= this.arcsInfo.Find(x => x.InitNodeId == route[index - 1] && x.EndNodeId == route[index]).Distance;
distance -= this.arcsInfo.Find(x => x.InitNodeId == route[index + 1] && x.EndNodeId == route[index + 2]).Distance;
var tmp = route[index];
route[index] = route[index + 1];
route[index + 1] = tmp;
distance += this.arcsInfo.Find(x => x.InitNodeId == route[index - 1] && x.EndNodeId == route[index]).Distance;
distance += this.arcsInfo.Find(x => x.InitNodeId == route[index + 1] && x.EndNodeId == route[index + 2]).Distance;
var child = new BestSoFar(this.startingNode.NodeId, this.endNodeId)
{
Route = route,
RouteDistance = distance,
LocalSearch = true
};
children.Add(child);
}
return(children);
}
//starts the search
public double[][] FindRoute()
{
for (var i = 0; i < this.iterations; i++)
{
//initializes pheromone ammount in all arcs
this.InitializePheromone();
var bestAnt = this.ConstructSolutions();
var iterationBest = this.LocalSearch(bestAnt);
iterationBest.Iteration = i;
if (this.bestSoFar == null || this.bestSoFar.Route.Count != this.nodes.Count)
{
this.bestSoFar = iterationBest;
}
else
{
this.bestSoFar = this.bestSoFar.RouteDistance < iterationBest.RouteDistance ? this.bestSoFar : iterationBest;
}
//this.UpdateStats(i);
this.UpdatePheromone();
}
var bestRoute = this.bestSoFar.GetOrderedRoute();
var bestRouteArray = this.RouteToArray(bestRoute);
this.bestSoFar = null; //if I run the method w/o reinstancing the Problem object best so far must be reinitialized or it will carry to the next run
return(bestRouteArray);
}
