public static FormulaGenerationArguments CreateRandom(Random random, Bounds<int> dimensionCountBounds, Bounds<int> minimalDepthBounds,
Bounds leafProbabilityBounds, Bounds constantProbabilityBounds, Bounds constantBounds, IDictionary<Operator, Bounds> operatorAndMaxProbabilityBoundsMap,
Operator[] obligatoryOperators, Bounds unaryVsBinaryOperatorsProbabilityBounds)
{
Dictionary<Operator, double> operatorAndProbabilityMap = operatorAndMaxProbabilityBoundsMap.ToDictionary(e => e.Key, e => random.Next(e.Value));
Operator[] unaryOperators = operatorAndMaxProbabilityBoundsMap.Keys.Where(op => op.Arity == 1).ToArray();
Operator[] binaryOperators = operatorAndMaxProbabilityBoundsMap.Keys.Where(op => op.Arity == 2).ToArray();
int unaryOperatorsToDeleteCount = random.Next(new Bounds<int>(0, unaryOperators.Length - 1));
int binaryOperatorsToDeleteCount = random.Next(new Bounds<int>(0, binaryOperators.Length - 1));
var unaryOperatorsToDelete = random.TakeDistinct(unaryOperators, unaryOperatorsToDeleteCount).Where(op => obligatoryOperators.All(o => o != op));
var binaryOperatorsToDelete = random.TakeDistinct(binaryOperators, binaryOperatorsToDeleteCount).Where(op => obligatoryOperators.All(o => o != op));
var operatorsToDelete = unaryOperatorsToDelete.Concat(binaryOperatorsToDelete);
foreach (var op in operatorsToDelete)
{
operatorAndProbabilityMap.Remove(op);
}
double ubp = random.Next(unaryVsBinaryOperatorsProbabilityBounds);
double ups = operatorAndProbabilityMap.Where(e => e.Key.Arity == 1).Sum(e => e.Value);
double bps = operatorAndProbabilityMap.Where(e => e.Key.Arity == 2).Sum(e => e.Value);
double correctionCoef = ubp / (1 - ubp) * bps / ups;
operatorAndProbabilityMap.Select(e => e.Key).Where(op => op.Arity == 1).ToArray().
ForEach(op => operatorAndProbabilityMap[op] *= correctionCoef);
return new FormulaGenerationArguments
{
DimensionsCount = random.Next(dimensionCountBounds),
MinimalDepth = random.Next(minimalDepthBounds),
LeafProbability = random.Next(leafProbabilityBounds),
ConstantProbability = random.Next(constantProbabilityBounds),
OperatorAndProbabilityMap = operatorAndProbabilityMap,
CreateConstant = () =>
{
double c = Math.Round(random.Next(constantBounds), 2);
return Math.Abs(c - 0) < 0.01 ? 0.01 : c;
}
};
}
