source: java/ecj/statistics/AverageObjectiveFitnessChartStatistics.java @ 42

package cecj.statistics;

import ec.EvolutionState;
import ec.display.chart.XYSeriesChartStatistics;
import ec.util.Parameter;

public class AverageObjectiveFitnessChartStatistics extends XYSeriesChartStatistics {

        private static final String P_POP = "pop";
        private static final String P_SIZE = "subpops";
        private static final String P_FREQUENCY = "frequency";
        private static final String P_FITNESS_CALCULATOR = "fitness-calc";

        private int numSubpopulations;
        private int[] seriesID;
        private int frequency;

        private ObjectiveFitnessCalculator fitnessCalc;

        @Override
        public void setup(EvolutionState state, Parameter base) {
                super.setup(state, base);

                Parameter fitnessCalcParameter = base.push(P_FITNESS_CALCULATOR);
                fitnessCalc = (ObjectiveFitnessCalculator) state.parameters
                        .getInstanceForParameter(fitnessCalcParameter, null, ObjectiveFitnessCalculator.class);
                fitnessCalc.setup(state, fitnessCalcParameter);

                Parameter frequencyParam = base.push(P_FREQUENCY);
                frequency = state.parameters.getIntWithDefault(frequencyParam, null, 1);

                Parameter popSizeParameter = new Parameter(P_POP).push(P_SIZE);
                numSubpopulations = state.parameters.getInt(popSizeParameter, null, 0);
                seriesID = new int[numSubpopulations];
                for (int i = 0; i < numSubpopulations; ++i) {
                        seriesID[i] = addSeries("SubPop " + i);
                }
        }

        @Override
        public void postEvaluationStatistics(EvolutionState state) {
                super.postEvaluationStatistics(state);

                if (state.generation % frequency != 0) {
                        return;
                }

                for (int subPop = 0; subPop < numSubpopulations; ++subPop) {
                        double averageFitness = 0;
                        for (int i = 0; i < state.population.subpops[subPop].individuals.length; ++i) {
                                averageFitness += fitnessCalc
                                        .calculateObjectiveFitness(state,
                                                                                                state.population.subpops[subPop].individuals[i]);
                        }
                        averageFitness /= state.population.subpops[subPop].individuals.length;

                        addDataPoint(seriesID[subPop], state.generation, averageFitness);
                }
        }
}