Terrarium

A TypeScript/JavaScript framework that attempts to simplify the process of writing a genetic algorithm.

Rationale

There are some things that are exactly the same between all (or most) genetic algorithms (performing crossover when creating a new generation, selecting parents based on some metric for fitness, etc.). There are other things that are always different between genetic algorithms (how fitness is calculated, the "form" of a member of the population).

My goal in writing this was to create a framework that takes, as input, all of the things that are unique to each implementation of a genetic algorithm and put them together for the user so they don't have to worry about it.

Don't get it twisted. While this framework might make it easier to write a genetic algorithm, you'll probably struggle to use it if you don't already know how they work.

Intro

There are two main types that the framework defines:

• GeneticAlgorithmModel
• GeneticAlgorithm

GeneticAlgorithmModel is basically the "state" of your ecosystem at any given moment. I think it can be thought of as the "model" of a program that implements model-view-controller design (MVC).

GeneticAlgorithm is a wrapper around the model that might be thought of as the "controller" in MVC. It abstracts running the genetic algorithm behind a play() function. The genetic algorithm can be stopped at any point with the pause() function.

Basic Usage:

1. Define the necessary functions:

   • createOrganism
   • stepFunction
   • calculateFitness
   • crossover
   • mutate
   • shouldTerminate
   • shouldProgressGeneration

2. Pick out your hyperparameters:

   • populationSize
   • mutationRate

3. Create a GeneticAlgorithm.

    let geneticAlgorithm = new GeneticAlgorithm(
      createOrganism,
      stepFunction,
      calculateFitness,
      crossover,
      mutate,
      shouldTerminate,
      shouldProgressGeneration
    );
   

4. Start the genetic algorithm.

    geneticAlgorithm.play();
   

5. Optionally, read the model and display it however you like:

    # this infinite loop probably isn't the best way to do this
    while (true) {
      display(geneticAlgorithm.model);
    }
   

   Note: you have to write the code for display(). This function can be thought of as the "view" in MVC.f

Other Documentation

• In-Depth Usage Guide
• Design Notes