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  • PyNeurGen 0.30 Released

  • Tags: python neural networks

    Python Neural Genetic Hybrids can combine the use of genetic algorithms and neural networks.


    An updated version of PyNeurGen which is Python Neural Genetic Algrorithms, has been uploaded. This software package implements a pure Python version of neural networks and a version of genetic algorithms, grammatical evolution.

    It has been awhile since the last update. A major portion of the work entailed writing unit testing for the various modules. While some testing was done originally, in the intervening period I have developed a much greater appreciation for test functions, and so I went back and increased the coverage to somewhere around 90%. Some refactoring was necessary to break up functions into smaller more easily testable chunks.

    In addition, some functions are improved. I reworked the stopping criteria for grammatical evolution. Normally, the determination of when to stop the evolutionary process revolves around when the figure of merit, the fitness value. The fitness value, generated by the process for each genotype, must become sufficiently great or small, depending upon the objective. When the hurdle is reached, it is time to stop. The other typical reason to stop the process is when a maximum number of generations has been reached.

    PyNeurGen now enables custom fitness functions that among other things can enable an evolutionary process that tries build a distribution of solutions. Suppose that the fitness value is only a loose proxy for what you really want to do. In such cases, it may be that all of the fitness values in an upper range could signify genotypes that are suitable for that purpose. In situations like that, it makes more sense to think of building a population where, for example, the upper quartile must be above a hurdle fitness value. With the custom functions, that can be done now. In fact, any distribution of fitness values can be used as the stopping criteria.