Fitness function for symbolic regression (function approximation) problem

Namespace:  AForge.Genetic
Assembly:  AForge.Genetic (in AForge.Genetic.dll) Version: 2.2.4.0 (2.2.4.0)

Syntax

C#
public class SymbolicRegressionFitness : IFitnessFunction

Remarks

The fitness function calculates fitness value of GP and GEP chromosomes with the aim of solving symbolic regression problem. The fitness function’s value is computed as:

CopyC#
100.0 / ( error + 1 )
where error equals to the sum of absolute differences between function values (computed using the function encoded by chromosome) and input values (function to be approximated).

Sample usage:

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// constants
double[] constants = new double[5] { 1, 2, 3, 5, 7 };
// function to be approximated
double[,] data = new double[5, 2] {
    {1, 1}, {2, 3}, {3, 6}, {4, 10}, {5, 15} };
// create population
Population population = new Population( 100,
    new GPTreeChromosome( new SimpleGeneFunction( 1 + constants.Length ) ),
    new SymbolicRegressionFitness( data, constants ),
    new EliteSelection( ) );
// run one epoch of the population
population.RunEpoch( );

Inheritance Hierarchy

System..::.Object
  AForge.Genetic..::.SymbolicRegressionFitness

See Also