/// <summary>
/// Runs a set of parameter sets and returns the results.
/// </summary>
/// <param name="functionToMinimize"></param>
/// <param name="threshold"></param>
/// <param name="parameterSets"></param>
/// <param name="best"></param>
/// <returns></returns>
public List <OptimizerResult> RunParameterSets(
Func <double[], OptimizerResult> functionToMinimize,
double threshold,
double[][] parameterSets,
out OptimizerResult best)
{
OptimizerResult bestResult = null;
var results = new List <OptimizerResult>();
foreach (var parameterSet in parameterSets)
{
// Get the current parameters for the current point
var result = functionToMinimize(parameterSet);
results.Add(result);
if (bestResult == null)
{
bestResult = result;
}
else if (result.Error < bestResult.Error)
{
bestResult = result;
}
if (result.Error < threshold)
{
break;
}
}
best = bestResult;
return(results);
}
private IReadOnlyCollection <OptimizerResult> Optimize(
Func <double[], OptimizerResult> functionToMinimize,
double threshold,
out OptimizerResult best)
{
var initialParameterSets = ProposeParameterSets(m_randomStartingPointsCount, null);
// Initialize the search
var results = new List <OptimizerResult>();
var initializationResults = RunParameterSets(functionToMinimize, threshold, initialParameterSets, out best);
if ((best != null) && (best.Error < threshold))
{
return(results);
}
results.AddRange(initializationResults);
for (var iteration = 0; iteration < m_iterations; iteration++)
{
var parameterSets = ProposeParameterSets(m_functionEvaluationsPerIterationCount, results);
var iterationResults = RunParameterSets(functionToMinimize, threshold, parameterSets, out best);
results.AddRange(iterationResults);
if ((best != null) && (best.Error < threshold))
{
return(results);
}
}
return(results);
}
/// <summary>
/// Optimization using swarm optimization. Returns results for all particles.
/// </summary>
/// <param name="functionToMinimize"></param>
/// <returns></returns>
public OptimizerResult[] Optimize(Func <double[], OptimizerResult> functionToMinimize)
{
var particles = new double[m_numberOfParticles][];
var particleVelocities = Enumerable.Range(0, m_numberOfParticles)
.Select(p => new double[m_parameters.Length])
.ToArray();
// initialize max and min velocities
var maxParticleVelocities = new double[m_parameters.Length];
var minParticleVelocities = new double[m_parameters.Length];
for (int i = 0; i < m_parameters.Length; i++)
{
maxParticleVelocities[i] = Math.Abs(m_parameters[i].Max - m_parameters[i].Min);
minParticleVelocities[i] = -maxParticleVelocities[i];
}
// initialize max and min parameter bounds
var maxParameters = new double[m_parameters.Length];
var minParameters = new double[m_parameters.Length];
for (int i = 0; i < m_parameters.Length; i++)
{
maxParameters[i] = m_parameters[i].Max;
minParameters[i] = m_parameters[i].Min;
}
var pBest = Enumerable.Range(0, m_numberOfParticles)
.Select(p => new double[m_parameters.Length])
.ToArray();
var pBestScores = Enumerable.Range(0, m_numberOfParticles)
.Select(p => double.MaxValue)
.ToArray();
var gBest = new OptimizerResult(new double[m_parameters.Length], double.MaxValue);
// random initialize particles
for (int i = 0; i < m_numberOfParticles; i++)
{
particles[i] = RandomSearchOptimizer.SampleParameterSet(m_parameters, m_sampler);
}
// iterate for find best
for (int iterations = 0; iterations < m_maxIterations; iterations++)
{
Parallel.For(0, m_numberOfParticles, new ParallelOptions {
MaxDegreeOfParallelism = m_maxDegreeOfParallelism
}, (i) =>
{
var result = functionToMinimize(particles[i]);
lock (m_bestLocker)
{
if (result.Error < pBestScores[i])
{
pBest[i] = result.ParameterSet;
pBestScores[i] = result.Error;
}
if (result.Error < gBest.Error)
{
gBest = new OptimizerResult(result.ParameterSet.ToArray(), result.Error);
//Trace.WriteLine(gBest.Error);
}
}
});
for (int i = 0; i < m_numberOfParticles; i++)
{
//v[] = v[] + c1 * rand() * (pbest[] - present[]) + c2 * rand() * (gbest[] - present[])
particleVelocities[i] = particleVelocities[i].Add(pBest[i].Subtract(particles[i]).Multiply(m_c1 * m_random.NextDouble())
.Add(gBest.ParameterSet.Subtract(particles[i]).Multiply(m_c2 * m_random.NextDouble())));
BoundCheck(particleVelocities[i], maxParticleVelocities, minParticleVelocities);
//present[] = persent[] + v[]
particles[i] = particles[i].Add(particleVelocities[i]);
BoundCheck(particles[i], maxParameters, minParameters);
}
}
var results = new List <OptimizerResult>();
for (int i = 0; i < m_numberOfParticles; i++)
{
results.Add(new OptimizerResult(pBest[i], pBestScores[i]));
}
return(results.ToArray());
}
private IReadOnlyCollection <OptimizerResult> Optimize(Func <double[], OptimizerResult> functionToMinimize, double threshold, out OptimizerResult best)
{
OptimizerResult bestResult = null;
// Generate the cartesian product between all parameters
var grid = CartesianProduct(m_parameters);
// Initialize the search
var results = new ConcurrentBag <OptimizerResult>();
if (!m_runParallel)
{
foreach (var param in grid)
{
// Get the current parameters for the current point
var result = functionToMinimize(param);
results.Add(result);
if (bestResult == null)
{
bestResult = result;
}
else if (result.Error < bestResult.Error)
{
bestResult = result;
}
if (result.Error < threshold)
{
break;
}
}
}
else
{
var rangePartitioner = Partitioner.Create(grid, true);
var options = new ParallelOptions {
MaxDegreeOfParallelism = m_maxDegreeOfParallelism
};
Parallel.ForEach(rangePartitioner, options, (param, loopState) =>
{
// Get the current parameters for the current point
var result = functionToMinimize(param);
results.Add(result);
lock (results)
{
if (bestResult == null)
{
bestResult = result;
}
else if (result.Error < bestResult.Error)
{
bestResult = result;
}
}
if (result.Error < threshold)
{
loopState.Break();
}
});
}
best = bestResult;
return(results);
}
/// <summary>
/// Optimization using swarm optimization.
/// Returns the final results ordered from best to worst (minimized).
/// </summary>
/// <param name="functionToMinimize"></param>
/// <returns></returns>
public OptimizerResult[] Optimize(Func <double[], OptimizerResult> functionToMinimize)
{
var particles = new double[m_numberOfParticles][];
var particleVelocities = Enumerable.Range(0, m_numberOfParticles)
.Select(p => new double[m_parameters.Length])
.ToArray();
// initialize max and min velocities
var maxParticleVelocities = new double[m_parameters.Length];
var minParticleVelocities = new double[m_parameters.Length];
for (int i = 0; i < m_parameters.Length; i++)
{
maxParticleVelocities[i] = Math.Abs(m_parameters[i].Max() - m_parameters[i].Min());
minParticleVelocities[i] = -maxParticleVelocities[i];
}
// initialize max and min parameter bounds
var maxParameters = new double[m_parameters.Length];
var minParameters = new double[m_parameters.Length];
for (int i = 0; i < m_parameters.Length; i++)
{
maxParameters[i] = m_parameters[i].Max();
minParameters[i] = m_parameters[i].Min();
}
var pBest = Enumerable.Range(0, m_numberOfParticles)
.Select(p => new double[m_parameters.Length])
.ToArray();
var pBestScores = Enumerable.Range(0, m_numberOfParticles)
.Select(p => double.MaxValue)
.ToArray();
var gBest = new OptimizerResult(new double[m_parameters.Length], double.MaxValue);
// random initialize particles
for (int i = 0; i < m_numberOfParticles; i++)
{
particles[i] = CreateParticle();
}
// iterate for find best
for (int iterations = 0; iterations < m_maxIterations; iterations++)
{
for (int i = 0; i < m_numberOfParticles; i++)
{
var result = functionToMinimize(particles[i]);
if (result.Error < pBestScores[i])
{
pBest[i] = result.ParameterSet;
pBestScores[i] = result.Error;
}
if (result.Error < gBest.Error)
{
gBest = new OptimizerResult(result.ParameterSet.ToArray(), result.Error);
//Trace.WriteLine(gBest.Error);
}
}
for (int i = 0; i < m_numberOfParticles; i++)
{
//v[] = v[] + c1 * rand() * (pbest[] - present[]) + c2 * rand() * (gbest[] - present[])
particleVelocities[i] = particleVelocities[i].Add(pBest[i].Subtract(particles[i]).Multiply(m_c1 * m_random.NextDouble())
.Add(gBest.ParameterSet.Subtract(particles[i]).Multiply(m_c2 * m_random.NextDouble())));
BoundCheck(particleVelocities[i], maxParticleVelocities, minParticleVelocities);
//present[] = persent[] + v[]
particles[i] = particles[i].Add(particleVelocities[i]);
BoundCheck(particles[i], maxParameters, minParameters);
}
}
var results = new List <OptimizerResult>();
for (int i = 0; i < m_numberOfParticles; i++)
{
results.Add(new OptimizerResult(pBest[i], pBestScores[i]));
}
return(results.Where(v => !double.IsNaN(v.Error)).OrderBy(r => r.Error).ToArray());
}
private IReadOnlyCollection <OptimizerResult> Optimize(Func <double[], OptimizerResult> functionToMinimize, double threshold, out OptimizerResult best)
{
OptimizerResult bestResult = null;
var dim = m_parameters.Length;
var initialPoint = new double[dim];
var allResults = new List <OptimizerResult>();
m_totalFunctionEvaluations = 0;
for (var restarts = 0; restarts < m_maxRestarts; restarts++)
{
RandomRestartPoint(initialPoint);
var prevBest = EvaluateFunction(functionToMinimize, initialPoint);
var iterationsWithoutImprovement = 0;
var concurrentResults = new ConcurrentBag <OptimizerResult>
{
new OptimizerResult(prevBest.ParameterSet, prevBest.Error)
};
var options = new ParallelOptions {
MaxDegreeOfParallelism = m_maxDegreeOfParallelism
};
Parallel.For(0, dim, options, (i, loopState) =>
{
var a = (0.02 + (0.08 * m_random.NextDouble())) * (m_parameters[i].Max - m_parameters[i].Min); // % simplex size between 2%-8% of min(xrange)
var p = (a * ((Math.Sqrt(dim + 1) + dim) - 1)) / (dim * Math.Sqrt(2));
var q = (a * (Math.Sqrt(dim + 1) - 1)) / (dim * Math.Sqrt(2));
var x = initialPoint.ToArray();
x[i] = x[i] + p;
for (var j = 0; j < dim; j++)
{
if (j != i)
{
x[j] = x[j] + q;
}
}
BoundCheck(x);
var result = EvaluateFunction(functionToMinimize, x);
concurrentResults.Add(result);
lock (concurrentResults)
{
if (bestResult == null)
{
bestResult = result;
}
else if (result.Error < bestResult.Error)
{
bestResult = result;
}
}
if (result.Error < threshold)
{
loopState.Break();
}
});
var results = concurrentResults.ToList();
if (bestResult.Error < threshold)
{
allResults.AddRange(results);
break;
}
// simplex iter
var iterations = 0;
while (true)
{
results = results.OrderBy(r => r.Error).ToList();
var iterationBest = results.First();
// break after m_maxIterationsPrRestart
if ((iterations >= m_maxIterationsPrRestart) && (m_maxIterationsPrRestart != 0))
{
allResults.AddRange(results);
break;
}
iterations++;
if (iterationBest.Error < (prevBest.Error - m_noImprovementThreshold))
{
iterationsWithoutImprovement = 0;
prevBest = iterationBest;
}
else
{
iterationsWithoutImprovement++;
}
// break after no_improv_break iterations with no improvement
if (iterationsWithoutImprovement >= m_maxIterationsWithoutImprovement)
{
allResults.AddRange(results);
break;
}
// check if m_maxFunctionEvaluations is reached
if ((m_totalFunctionEvaluations >= m_maxFunctionEvaluations) && (m_maxFunctionEvaluations != 0))
{
allResults.AddRange(results);
break;
}
// centroid
var x0 = new double[dim];
foreach (var tup in results.Take(results.Count - 1))
{
var parameters = tup.ParameterSet;
for (var i = 0; i < parameters.Length; i++)
{
x0[i] += parameters[i] / (results.Count - 1);
}
}
BoundCheck(x0);
// reflection
var last = results.Last();
var xr = x0.Add(x0.Subtract(last.ParameterSet).Multiply(m_alpha));
BoundCheck(xr);
var refelctionScore = EvaluateFunction(functionToMinimize, xr);
var first = results.First().Error;
if ((first <= refelctionScore.Error) && (refelctionScore.Error < results[results.Count - 2].Error))
{
results.RemoveAt(results.Count - 1);
results.Add(refelctionScore);
continue;
}
// expansion
if (refelctionScore.Error < first)
{
var xe = x0.Add(x0.Subtract(last.ParameterSet).Multiply(m_gamma));
BoundCheck(xe);
var expansionScore = EvaluateFunction(functionToMinimize, xe);
if (expansionScore.Error < refelctionScore.Error)
{
results.RemoveAt(results.Count - 1);
results.Add(expansionScore);
continue;
}
else
{
results.RemoveAt(results.Count - 1);
results.Add(refelctionScore);
continue;
}
}
// contraction
var xc = x0.Add(x0.Subtract(last.ParameterSet).Multiply(m_rho));
BoundCheck(xc);
var contractionScore = EvaluateFunction(functionToMinimize, xc);
if (contractionScore.Error < last.Error)
{
results.RemoveAt(results.Count - 1);
results.Add(contractionScore);
continue;
}
// shrink
var x1 = results[0].ParameterSet;
var nres = new List <OptimizerResult>();
foreach (var tup in results)
{
var xs = x1.Add(x1.Subtract(tup.ParameterSet).Multiply(m_sigma));
BoundCheck(xs);
var score = EvaluateFunction(functionToMinimize, xs);
nres.Add(score);
}
results = nres.ToList();
}
// check if m_maxFunctionEvaluations is reached
if ((m_totalFunctionEvaluations >= m_maxFunctionEvaluations) && (m_maxFunctionEvaluations != 0))
{
allResults.AddRange(results);
break;
}
}
best = bestResult;
return(allResults);
}
/// <summary>
/// Runs a set of parameter sets and returns the results.
/// </summary>
/// <param name="functionToMinimize"></param>
/// <param name="threshold"></param>
/// <param name="parameterSets"></param>
/// <param name="best"></param>
/// <returns></returns>
public IReadOnlyCollection <OptimizerResult> RunParameterSets(
Func <double[], OptimizerResult> functionToMinimize,
double threshold,
double[][] parameterSets,
out OptimizerResult best)
{
OptimizerResult bestResult = null;
var results = new ConcurrentBag <OptimizerResult>();
if (!m_runParallel)
{
foreach (var parameterSet in parameterSets)
{
// Get the current parameters for the current point
var result = functionToMinimize(parameterSet);
results.Add(result);
if (bestResult == null)
{
bestResult = result;
}
else if (result.Error < bestResult.Error)
{
bestResult = result;
}
if (result.Error < threshold)
{
break;
}
}
}
else
{
var rangePartitioner = Partitioner.Create(parameterSets, true);
var options = new ParallelOptions {
MaxDegreeOfParallelism = m_maxDegreeOfParallelism
};
Parallel.ForEach(
rangePartitioner,
options,
(param, loopState) =>
{
// Get the current parameters for the current point
var result = functionToMinimize(param);
results.Add(result);
lock (results)
{
if (bestResult == null)
{
bestResult = result;
}
else if (result.Error < bestResult.Error)
{
bestResult = result;
}
}
if (result.Error < threshold)
{
loopState.Break();
}
}
);
}
best = bestResult;
return(results);
}
