/// <summary>
/// Calculates the standard deviation of the values of the <see cref="GeneticEntity.ScaledFitnessValue"/>
/// property in the <paramref name="population"/>.
/// </summary>
/// <param name="population"><see cref="Population"/> from which to derive the metric.</param>
/// <returns>Standard deviation of the values of the <see cref="GeneticEntity.ScaledFitnessValue"/> property.</returns>
/// <exception cref="ArgumentNullException"><paramref name="population"/> is null.</exception>
public override object?GetResultValue(Population population)
{
if (population == null)
{
throw new ArgumentNullException(nameof(population));
}
this.AssertIsInitialized();
// If there's no fitness scaling, just use the raw max value.
if (this.Algorithm !.FitnessScalingStrategy == null)
{
return(population.RawStandardDeviation);
}
MeanFitness meanFitness = this.Algorithm.Metrics.OfType <MeanFitness>().First();
return(MathHelper.GetStandardDeviation(
population.Entities,
(double)meanFitness.GetResults(population.Index).Last().ResultValue,
FitnessType.Scaled));
}