/// <summary>
/// Adds a next chain to a given layout.
/// </summary>
/// <param name="layout"></param>
/// <param name="chainNumber"></param>
/// <returns></returns>
protected virtual TLayout AddChain(TLayout layout, int chainNumber)
{
if (chainNumber >= chains.Count)
{
throw new ArgumentException("Chain number is bigger than then number of chains.", nameof(chainNumber));
}
layout = layout.SmartClone();
layoutOperations.AddChain(layout, chains[chainNumber], true);
return(layout);
}
public IEnumerable <TLayout> Evolve(TLayout initialLayout, Chain <TNode> chain, int count)
{
for (int i = 0; i < count; i++)
{
var copy = initialLayout.SmartClone();
layoutOperations.AddChain(copy, chain.Nodes, true, out var iterationsCount);
foreach (var _ in chain.Nodes)
{
OnPerturbed?.Invoke(this, copy);
}
if (layoutOperations.IsLayoutValid(copy))
{
// TODO: why chain.Nodes instead of chain?
if (layoutOperations.TryCompleteChain(copy, chain.Nodes))
{
yield return(copy);
}
}
}
}
/// <inheritdoc />
public IEnumerable <TLayout> Evolve(TLayout initialLayout, Chain <TNode> chain, int count)
{
var configuration = GetConfiguration(chain.Number);
if (!chain.IsFromFace && configuration.HandleTreesGreedily)
{
var iters = 0;
var lastEventIters = 0;
for (int i = 0; i < 2; i++)
{
if (CancellationToken.HasValue && CancellationToken.Value.IsCancellationRequested)
{
yield break;
}
for (int k = 0; k < 1; k++)
{
if (CancellationToken.HasValue && CancellationToken.Value.IsCancellationRequested)
{
yield break;
}
var copy = initialLayout.SmartClone();
LayoutOperations.AddChain(copy, chain.Nodes, true, out var addChainIterationsCount);
iters += addChainIterationsCount;
// An event must be sent in order for the early stopping handler to work
OnPerturbed?.Invoke(this, copy);
if (CancellationToken.HasValue && CancellationToken.Value.IsCancellationRequested)
{
yield break;
}
if (LayoutOperations.IsLayoutValid(copy))
{
if (LayoutOperations.TryCompleteChain(copy, chain.Nodes))
{
OnPerturbed?.Invoke(this, copy);
if (CancellationToken.HasValue && CancellationToken.Value.IsCancellationRequested)
{
yield break;
}
OnEvent?.Invoke(this, new SimulatedAnnealingEventArgs()
{
Type = SimulatedAnnealingEventType.LayoutGenerated,
IterationsSinceLastEvent = iters - lastEventIters,
IterationsTotal = iters,
LayoutsGenerated = -1,
ChainNumber = chain.Number,
});
lastEventIters = iters;
yield return(copy);
break;
}
}
OnEvent?.Invoke(this, new SimulatedAnnealingEventArgs()
{
Type = SimulatedAnnealingEventType.OutOfIterations,
IterationsSinceLastEvent = iters - lastEventIters,
IterationsTotal = iters,
LayoutsGenerated = -1,
ChainNumber = chain.Number,
});
lastEventIters = iters;
}
}
yield break;
}
if (addNodesGreedilyBeforeEvolve)
{
LayoutOperations.AddChain(initialLayout, chain.Nodes, true, out var addChainIterationsCount);
}
const double p0 = 0.2d;
const double p1 = 0.01d;
var t0 = -1d / Math.Log(p0);
var t1 = -1d / Math.Log(p1);
var ratio = Math.Pow(t1 / t0, 1d / (configuration.Cycles - 1));
var deltaEAvg = 0d;
var acceptedSolutions = 1;
var t = t0;
var layouts = new List <TLayout>();
var originalLayout = initialLayout;
var currentLayout = originalLayout;
#region Debug output
//if (withDebugOutput)
//{
// Console.WriteLine($"Initial energy: {layoutOperations.GetEnergy(currentLayout)}");
//}
#endregion
var numberOfFailures = 0;
var stageTwoFailures = 0;
var iterations = 0;
var lastEventIterations = 0;
var shouldStop = false;
for (var i = 0; i < configuration.Cycles; i++)
{
var wasAccepted = false;
#region Random restarts
if (enableRandomRestarts)
{
if (ShouldRestart(numberOfFailures))
{
OnEvent?.Invoke(this, new SimulatedAnnealingEventArgs()
{
Type = SimulatedAnnealingEventType.RandomRestart,
IterationsSinceLastEvent = iterations - lastEventIterations,
IterationsTotal = iterations,
LayoutsGenerated = layouts.Count,
ChainNumber = chain.Number,
});
yield break;
}
}
#endregion
if (iterations - lastEventIterations > configuration.MaxIterationsWithoutSuccess)
{
break;
}
if (shouldStop)
{
break;
}
for (var j = 0; j < configuration.TrialsPerCycle; j++)
{
if (CancellationToken.HasValue && CancellationToken.Value.IsCancellationRequested)
{
yield break;
}
if (stageTwoFailures > configuration.MaxStageTwoFailures)
{
shouldStop = true;
break;
}
iterations++;
var perturbedLayout = PerturbLayout(currentLayout, chain.Nodes, out var energyDelta);
OnPerturbed?.Invoke(this, perturbedLayout);
// TODO: can we check the energy instead?
if (LayoutOperations.IsLayoutValid(perturbedLayout, chain.Nodes))
{
#region Random restarts
if (enableRandomRestarts && randomRestartsSuccessPlace == RestartSuccessPlace.OnValid)
{
wasAccepted = true;
if (randomRestartsResetCounter)
{
numberOfFailures = 0;
}
}
#endregion
// TODO: wouldn't it be too slow to compare againts all?
if (IsDifferentEnough(perturbedLayout, layouts))
{
// TODO 2SG: should we clone before TryCompleteChain or should TryCompleteChain not change the layout?
var newLayout = perturbedLayout.SmartClone();
var shouldContinue = LayoutOperations.TryCompleteChain(newLayout, chain.Nodes);
if (shouldContinue)
{
layouts.Add(newLayout);
OnValid?.Invoke(this, newLayout);
#region Random restarts
if (enableRandomRestarts && randomRestartsSuccessPlace == RestartSuccessPlace.OnValidAndDifferent)
{
wasAccepted = true;
if (randomRestartsResetCounter)
{
numberOfFailures = 0;
}
}
#endregion
OnEvent?.Invoke(this, new SimulatedAnnealingEventArgs()
{
Type = SimulatedAnnealingEventType.LayoutGenerated,
IterationsSinceLastEvent = iterations - lastEventIterations,
IterationsTotal = iterations,
LayoutsGenerated = layouts.Count,
ChainNumber = chain.Number,
});
yield return(newLayout);
lastEventIterations = iterations;
stageTwoFailures = 0;
#region Debug output
//if (withDebugOutput)
//{
// Console.WriteLine($"Found layout, cycle {i}, trial {j}, energy {layoutOperations.GetEnergy(perturbedLayout)}");
//}
#endregion
if (layouts.Count >= count)
{
#region Debug output
//if (withDebugOutput)
//{
// Console.WriteLine($"Returning {layouts.Count} partial layouts");
//}
#endregion
yield break;
}
}
else
{
stageTwoFailures++;
OnEvent?.Invoke(this, new SimulatedAnnealingEventArgs()
{
Type = SimulatedAnnealingEventType.StageTwoFailure,
IterationsSinceLastEvent = iterations - lastEventIterations,
IterationsTotal = iterations,
LayoutsGenerated = layouts.Count,
ChainNumber = chain.Number,
ResetsIterationsSinceLastEvent = false,
});
}
}
}
var deltaAbs = Math.Abs(energyDelta);
var accept = false;
if (energyDelta > 0)
{
if (i == 0 && j == 0)
{
deltaEAvg = deltaAbs * 15;
}
var p = Math.Pow(Math.E, -deltaAbs / (deltaEAvg * t));
if (Random.NextDouble() < p)
{
accept = true;
}
}
else
{
accept = true;
}
if (accept)
{
acceptedSolutions++;
currentLayout = perturbedLayout;
deltaEAvg = (deltaEAvg * (acceptedSolutions - 1) + deltaAbs) / acceptedSolutions;
#region Random restarts
if (enableRandomRestarts && randomRestartsSuccessPlace == RestartSuccessPlace.OnAccepted)
{
wasAccepted = true;
if (randomRestartsResetCounter)
{
numberOfFailures = 0;
}
}
#endregion
}
}
if (!wasAccepted)
{
numberOfFailures++;
}
t = t * ratio;
}
OnEvent?.Invoke(this, new SimulatedAnnealingEventArgs()
{
Type = SimulatedAnnealingEventType.OutOfIterations,
IterationsSinceLastEvent = iterations - lastEventIterations,
IterationsTotal = iterations,
LayoutsGenerated = layouts.Count,
ChainNumber = chain.Number,
});
}