Jenetics:我如何在每一步访问进化结果(或统计数据)？

Question

我正在开发一个基于Jenetics框架(链接到jenetics.io)的优化引擎。我有一个进化引擎的定义如下：

final Thread engineStream = new Thread(() -> {
final MinMax<EvolutionResult<DoubleGene, Double>> best = MinMax.of();

_scannerEngine.stream()
    .limit(byPopulationConvergence(convergenceCriterion))
    .limit(result -> !Thread.currentThread().isInterrupted())                              
    .limit(maxGenerations)
    .peek(best).forEach(evolutionResult -> {
        waiting();
        if (callback != null) {
            callback.accept(evolutionResult, best.getMax());
        }
        final String generationCounter = String.valueOf(evolutionResult.getGeneration());
       _callingInstance.doOnAlgorithmCallback(new String("****** finished generation: " + generationCounter + " ****"));
    });
}

engineStream.start();

目前，我正在完成一个进化周期(通过人口进行一次迭代)，通过以下方式向我的UI发送消息：

peek(best).forEach(
    ...
    _callingInstance.doOnAlgorithmCallback(...)
)

我想要做的是在执行每个适应度步骤之后，将演化的当前状态(理想的一些统计数据包含当前的适应度平均值、最小值、最大值等)推到，这样用户就可以看到优化过程的当前状态。

有什么想法吗？

根据Franz Wilhelmst tter的建议最后执行：

final Thread engineStream = new Thread(() -> {
    final MinMax<EvolutionResult<DoubleGene, Double>> best = MinMax.of();

    try {
        _scannerEngine.stream() //
        // stop stream if fitness average across the population is smaller than % of best fitness
        .limit(byFitnessConvergence(5, 20, convergence%)) //
        .limit(interrupted -> !Thread.currentThread().isInterrupted()) //
        .limit(_geneticScanParameters.getMaxGenerationsLimit()) // maximum number of generations
        .peek(best) //
        .peek(_statistics) //
        .forEach(evolutionResult -> {
            waiting();
            if (callback != null) {
                MessageLogger.logError(getClass(), best.getMax().toString());
                if (_geneticScanParameters.getOptimizationStrategy() == Optimize.MAXIMUM) {
                    callback.accept(evolutionResult, best.getMax());
                } else if (_geneticScanParameters.getOptimizationStrategy() == Optimize.MINIMUM) {
                    callback.accept(evolutionResult, best.getMin());
                }
            }
            MessageLogger.log(getClass(), _statistics.toString());
            final String generationCounter = String.valueOf(evolutionResult.getGeneration());
            _callingInstance.doOnAlgorithmCallback(new String("****** finished generation: " + generationCounter + " ****"));
        });

        MessageLogger.log(getClass(), "\n" + _statistics.toString());
    } catch (final Exception ex) {
    MessageLogger.logError(getClass(), Thread.currentThread(), ex);
    }
    _callingInstance.doOnAlgorithmFinished();
});
engineStream.start();
_engineStream = engineStream;

请注意，我使用的约定是"_variable“是类属性。

Answer 1

为此，您可以使用EvolutionStatistics类。

final Engine<DoubleGene, Double> engine = ...
final EvolutionStatistics<Double, DoubleMomentStatistics> statistics =
    EvolutionStatistics.ofNumber();

final Phenotype<DoubleGene, Double> result = engine.stream()
    .limit(bySteadyFitness(7))
    .limit(100)
    .peek(statistics)
    .collect(toBestPhenotype());

System.println(statistics);

如果您更新peek方法中的类，您将得到一些额外的统计信息。