internal override void OnInitializing()
{
base.OnInitializing();
Console.ForegroundColor = ConsoleColor.Green;
SendMessage(MessageCode.GreedyStart, Type);
Console.ForegroundColor = ConsoleColor.Gray;
Tour = new CityMapGraph();
NodesQueue = new Queue <int>();
SolutionsHistory = new Collection <ToSolution>();
CityMapClone = Solver.CityMapGraph.DeepCopy();
_canDoImprovements = default;
int maxNodesToAdd = default;
if (Parameters.ContainsKey(ParameterCodes.CanDoImprovements))
{
_canDoImprovements = Parameters[ParameterCodes.CanDoImprovements];
}
if (Parameters.ContainsKey(ParameterCodes.GreedyMaxNodesToAdd))
{
maxNodesToAdd = Parameters[ParameterCodes.GreedyMaxNodesToAdd];
}
InitializeNodesQueue(maxNodesToAdd);
StartingPoint = CityMapClone.GetStartPoint();
if (StartingPoint is null)
{
throw new OperationCanceledException(
$"{nameof(StartingPoint)} in {nameof(NearestNeighbor)}");
}
StartingPoint.IsVisited = true;
_timeSpent = DateTime.Now;
}
/// <summary>
/// This implementation is the classic GetClosestNeighborByScore.
/// It returns the best candidate node near to point of interest passed as argument.
/// </summary>
/// <param name="interestPoint">Point of interest</param>
/// <returns></returns>
protected virtual InterestPointWorker GetBestNeighbor(InterestPointWorker interestPoint)
{
int bestScore = default;
InterestPointWorker candidateNode = default;
var adjPoiIds = CityMapClone.GetAdjacentNodes(interestPoint.Entity.Id);
adjPoiIds.ToList().ForEach(adjPoiId =>
{
var adjNode = CityMapClone[adjPoiId];
if (adjNode.IsVisited)
{
return;
}
var adjNodeScore = adjNode.Entity.Score.Value;
if (adjNodeScore > bestScore)
{
bestScore = adjNodeScore;
candidateNode = adjNode;
}
else if (adjNodeScore == bestScore)
{
CityMapGraph.SetRandomCandidateId(candidateNode, adjNode, out int pointId);
candidateNode = CityMapClone[pointId];
}
});
return(candidateNode);
}
/// <summary>
/// This implementation is the knapsack style Best Closest Neighbor variant.
/// Firstly it gets neighbors of point of interest passed by argument.
/// Secondly it orders that points by score / weight decreasing value.
/// The weight value is obtained by getting the edge between param node and the neighbor node.
/// Finally it returns the first not visited node of that point list.
/// </summary>
/// <param name="interestPoint">Point of interest</param>
/// <returns></returns>
protected override InterestPointWorker GetBestNeighbor(InterestPointWorker interestPoint)
{
var adjPoiIds = CityMapClone.GetAdjacentNodes(interestPoint.Entity.Id);
var tempNodes = new Collection <(int NodeKey, double Ratio)>();
adjPoiIds.ToList().ForEach(adjPoiId =>
{
var node = CityMapClone[adjPoiId];
if (node.IsVisited)
{
return;
}
RouteWorker edge = CityMapClone.GetEdge(interestPoint.Entity.Id, adjPoiId);
if (edge is null)
{
return;
}
var value = node.Entity.Score.Value / edge.Weight.Invoke();
tempNodes.Add((adjPoiId, value));
});
var tempNodesSorted = from node in tempNodes
orderby node.Ratio descending
select node.NodeKey;
InterestPointWorker candidateNode = default;
int candidateNodeId = tempNodesSorted.FirstOrDefault();
if (candidateNodeId != 0)
{
candidateNode = CityMapClone[candidateNodeId];
}
return(candidateNode);
}
