//
// Encog(tm) Core v3.2 - .Net Version
// http://www.heatonresearch.com/encog/
//
// Copyright 2008-2014 Heaton Research, Inc.
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// Licensed under the Apache License, Version 2.0 (the "License");
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//  http://www.apache.org/licenses/LICENSE-2.0
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// distributed under the License is distributed on an "AS IS" BASIS,
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using System.Collections.Generic;
using Encog.ML.EA.Genome;
using Encog.ML.EA.Train;

namespace Encog.ML.EA.Sort
{
    /// <summary>
    ///     Sort the gnomes for species.  Sort first by score, second by birth generation.
    ///     This favors younger genomes if scores are equal.
    /// </summary>
    public class SortGenomesForSpecies : IComparer<IGenome>
    {
        /// <summary>
        ///     The trainer.
        /// </summary>
        private readonly IEvolutionaryAlgorithm _train;

        /// <summary>
        ///     Construct the comparator.
        /// </summary>
        /// <param name="theTrain">The trainer.</param>
        public SortGenomesForSpecies(IEvolutionaryAlgorithm theTrain)
        {
            _train = theTrain;
        }

        /// <inheritdoc />
        public int Compare(IGenome g1, IGenome g2)
        {
            int result = _train.SelectionComparer.Compare(g1, g2);

            if (result != 0)
            {
                return result;
            }

            return g2.BirthGeneration - g1.BirthGeneration;
        }
    }
}
