source: java/ecj/interaction/LearnerTeacherInteractionScheme.java @ 42

package cecj.interaction;

import java.util.ArrayList;
import java.util.List;

import cecj.problems.TestBasedProblem;

import ec.EvolutionState;
import ec.Individual;
import ec.util.Parameter;

/**
 * 
 * @author Marcin Szubert
 * 
 */
public class LearnerTeacherInteractionScheme implements InteractionScheme {

        private static final String P_POP = "pop";
        private static final String P_ROLE = "role";
        private static final String P_SIZE = "subpops";
        private static final String P_SUBPOP = "subpop";

        /**
         * Number of subpopulations.
         */
        private int numSubpopulations;

        private TestBasedProblem problem;

        public enum Role {
                LEARNER, TEACHER
        }

        private Role[] subpopulationRoles;

        public void setup(EvolutionState state, Parameter base) {
                if (!(state.evaluator.p_problem instanceof TestBasedProblem)) {
                        state.output.fatal("Learner-teacher interactions need asymmetric problem definition\n");
                } else {
                        problem = (TestBasedProblem) state.evaluator.p_problem;
                }

                Parameter popSizeParameter = new Parameter(P_POP).push(P_SIZE);
                numSubpopulations = state.parameters.getInt(popSizeParameter, null, 0);
                if (numSubpopulations <= 0) {
                        state.output.fatal("Population size must be > 0.\n", popSizeParameter);
                }

                for (int subpop = 0; subpop < numSubpopulations; subpop++) {
                        Parameter subpopRoleParam = base.push(P_SUBPOP).push("" + subpop).push(P_ROLE);
                        String role = state.parameters.getString(subpopRoleParam, null);
                        if (role == null) {
                                state.output.fatal("Subpopulation role must be specified for the learner-teacher "
                                                + "interactions scheme\n", subpopRoleParam);
                        } else {
                                try {
                                        subpopulationRoles[subpop] = Enum.valueOf(Role.class, role.toUpperCase());
                                } catch (IllegalArgumentException ex) {
                                        state.output.fatal("Subpopulation role " + role
                                                        + " does not exist in the learner-teacher interactions scheme");
                                }
                        }
                }
        }

        public List<List<InteractionResult>> performInteractions(EvolutionState state, int subpop,
                        List<List<Individual>> opponents) {

                List<List<InteractionResult>> subpopulationResults = new ArrayList<List<InteractionResult>>();
                Individual[] inds = state.population.subpops[subpop].individuals;

                for (Individual ind : inds) {
                        List<InteractionResult> results = new ArrayList<InteractionResult>();
                        for (int subpop2 = 0; subpop2 < numSubpopulations; subpop2++) {
                                if (subpopulationRoles[subpop2] != subpopulationRoles[subpop]) {
                                        List<Individual> curOpponents = opponents.get(subpop2);
                                        for (Individual opponent : curOpponents) {
                                                if (subpopulationRoles[subpop] == Role.LEARNER) {
                                                        results.add(problem.test(state, ind, opponent).first);
                                                } else {
                                                        results.add(problem.test(state, opponent, ind).second);
                                                }
                                        }
                                }
                        }
                        subpopulationResults.add(results);
                }

                return subpopulationResults;
        }

        public List<Integer> getSubpopulationIndices(Role role) {
                List<Integer> result = new ArrayList<Integer>();
                for (int subpop = 0; subpop < numSubpopulations; subpop++) {
                        if (subpopulationRoles[subpop] == role) {
                                result.add(subpop);
                        }
                }
                return result;
        }
}