public void Forage(IAntColonyContext context)
{
if (context.Steps.Count == 0)
{
throw new ArgumentOutOfRangeException("No steps provided");
}
ICollection <IStep> availableSteps = context.Steps;
Int32 randomIndex = randomInstance.Next(availableSteps.Count());
// Set the initial start point
IStep currentStep = default(IStep);
if (availableSteps.Count > 0)
{
currentStep = availableSteps.ElementAt(randomIndex);
// Process each step until no steps remain
availableSteps = currentStep.Available(context).OfType <IStep>().ToList();
while (availableSteps.Count() > 0)
{
IStep nextStep = SelectNext(availableSteps);
(context.Path as INodePath).Add(nextStep, nextStep.Score);
currentStep = nextStep;
availableSteps = currentStep.Available(context).OfType <IStep>().ToList();
}
context.Path.Validate(context);
//Console.WriteLine("Path: {0}: {1}", context.Path.Score,
// (((INodePath) context.Path).Steps != null
// ? string.Join(",", ((INodePath) context.Path).Steps.Select(e => e.StepName))
// : ""));
}
}
public IEnumerable <IPheremoneKey> Available(IAntColonyContext context)
{
foreach (IPheremoneKey key in Edges.Where(e => !context.Path.Contains(e.StartStep.StepName.Equals(StepName) ? e.EndStep : e.StartStep)).OfType <IPheremoneKey>())
{
yield return(key);
}
}
public IEnumerable <IPheremoneKey> Available(IAntColonyContext context)
{
foreach (IPheremoneKey key in context.Steps.Where(s => !((context.Path as INodePath).Steps.OfType <IStep>().Any(k => k.Equals(s)))).OfType <IPheremoneKey>())
{
yield return(key);
}
}
public void Validate(object contextObject)
{
IAntColonyContext context = contextObject as IAntColonyContext;
if (Steps.Count != (context.Steps.Count - 1))
{
InvalidPath = true;
}
}
private void InitialisePathPheremones(IAntColonyContext context, IDictionary <IEdge, Pheremone> map, decimal initialPheremoneLevel)
{
AntColonyContext c = context as AntColonyContext;
foreach (IStep step in c.Steps)
{
//if (!map.ContainsKey(step))
// map[step] = new Pheremone(initialPheremoneLevel);
}
}
/// <summary>
/// Initialise each of the ants.
/// <para>At this point is only required to make a clone
/// of the InitialContext for each of the ants to use</para>
/// </summary>
/// <param name="context">The initial context</param>
public void InitialiseAnts(IAntColonyContext context)
{
InitialContext = context;
Contexts = new List <IAntColonyContext>();
for (int i = 0; i < NumberOfAnts; ++i)
{
IAntColonyContext c = context.Clone() as IAntColonyContext;
c.Id = i + 1;
Contexts.Add(c);
}
}
/// <summary>
/// Set each of the ants out on it's forage track,
/// and wait for them all to return.
/// <para>Select the best path from all of paths travelled by
/// the ants and drop pheremones on that path.</para>
/// <para>Decay the pheremone level in all paths in the pheremone map</para>
/// <para>Repeat the above process for the required number of iterations</para>
/// <para>Return the result in the InitialContext.BestPaths property</para>
/// </summary>
public void RunAnts()
{
const int MaxRepetitions = 2000;
Int32 sameScore = 0;
InitialisePheremones();
ICollection <IPath> paths = new List <IPath>();
for (int i = 0; i < Iterations; ++i)
{
ICollection <TAnt> ants = new List <TAnt>(NumberOfAnts);
for (int a = 0; a < NumberOfAnts; ++a)
{
IAntColonyContext c = Contexts[a];
c.Reset();
TAnt ant = new TAnt();
ant.Initialise(a * i + 1, PheremoneMap, InitialPheremoneLevel);
ant.Context = c;
ants.Add(ant);
}
ants.AsParallel().ForEach(a => a.Forage(a.Context));
ICollection <IPath> bestPaths = DetermineBestPaths();
// If new paths are more efficient than old paths save them
if (paths.Count() == 0 || (paths.First().Score > bestPaths.First().Score))
{
paths = new List <IPath>(bestPaths);
sameScore = 0;
}
// If same score merge the set of paths
else if (paths.First().Score == bestPaths.First().Score)
{
paths = paths.Union(bestPaths).Distinct().ToList();
}
// TODO: Make the exit condition a predicate instead
if (sameScore++ > MaxRepetitions)
{
Console.WriteLine(string.Format("Exiting due to repetition of same score on iteration {0}", i));
break;
}
//Console.WriteLine("Iteration {0}: Score: {1} Returned: {2}", i, paths.First().Score, bestPaths.First().Score);
// Manage the pheremone levels after the iteration completes
PheremoneMap.ForEach(e => e.Value.Decay(EvaporationRate));
if (paths.First().Score < decimal.MaxValue)
{
paths.ForEach(p => DepositPheremones(PheremoneMap, (dynamic)p));
}
}
InitialContext.BestPaths = paths.OfType <IPath>().ToList();
}
public void Forage(IAntColonyContext context)
{
if (context.Steps.Count == 0)
{
throw new ArgumentOutOfRangeException("No steps provided");
}
ICollection <IStep> availableSteps = context.Steps;
Int32 randomIndex = randomInstance.Next(availableSteps.Count());
// Set the initial start point
IStep currentStep = default(IStep);
if (availableSteps.Count > 0)
{
//Console.WriteLine(string.Format("Initial random index = {0}", randomIndex));
currentStep = availableSteps.ElementAt(randomIndex);
//availableSteps.Remove(currentStep);
}
// Process each step until no steps remain
ICollection <IEdge> availableEdges = currentStep.Available(context).OfType <IEdge>().ToList();
while (availableEdges.Count() > 0)
{
IEdge nextEdge = SelectNext(availableEdges) as IEdge;
IStep nextStep;
if (nextEdge.StartStep.Equals(currentStep))
{
nextStep = nextEdge.EndStep;
}
else
{
nextStep = nextEdge.StartStep;
}
(context.Path as IPathPath).Add(currentStep, nextStep, nextEdge.Score);
currentStep = nextStep;
availableEdges = currentStep.Available(context).OfType <IEdge>().ToList();
}
context.Path.Validate(context);
//Console.WriteLine(string.Format("Path: {0} {1} {2}", context.Path.Score, context.Path.Edges.First().StartStep.StepName, string.Join(",", context.Path.Edges.Select(e => e.EndStep.StepName))));
}
//#region IComparable<IEdge<int>> Members
//public int CompareTo(IEdge<int> other)
//{
// if (other == null)
// return -1;
// if (Score.CompareTo(other.Score) != 0)
// return Score.CompareTo(other.Score);
// if (StartStep.CompareTo(other.StartStep) != 0)
// return Score.CompareTo(other.StartStep);
// return Score.CompareTo(other.EndStep);
//}
//#endregion
#region IPheremoneKey Members
public IEnumerable <IPheremoneKey> Available(IAntColonyContext context)
{
return(EndStep.Available(context));
}
