pycellga: A Python Package for Improved Cellular Genetic Algorithms

pycellga is a Python package that implements cellular genetic algorithms (CGAs) for optimizing complex problems. CGAs combine the principles of cellular automata and traditional genetic algorithms, utilizing a spatially structured population organized in a grid-like topology. This structure allows each individual to interact only with its neighboring individuals, promoting diversity and maintaining a balance between exploration and exploitation during the optimization process. pycellga has machine coded operators with byte implementations. Beside it has Alpha-male CGA, Machine Coded Compact CGA and Improved CGA with Machine Coded Operaors for real-valued optimization problems. The pycellga package is designed to handle a wide range of optimization problems, including binary, real-valued, and permutation-based challenges, making it a versatile tool for diverse applications in evolutionary computation.

Features

• Cellular Genetic Algorithm (cga): Efficient implementation of CGAs with various built-in functions for diverse applications.
• Improved CGA with Machine-Coded Operators: Enhanced performance in real-valued optimization problems through the use of machine-coded byte operators.
• Synchronous Cellular Genetic Algorithm (sync_cga): Simultaneous update of all individuals (cells) in each iteration for synchronized evolution.
• Alpha Male Cellular Genetic Algorithm (alpha_cga): Population divided into social groups, with each group consisting of females selecting the same alpha male.
• Compact Cellular Genetic Algorithm (ccga): Integrates the principles of Cellular Genetic Algorithms with those of Compact Genetic Algorithms for memory efficiency.
• Machine-Coded Compact Cellular Genetic Algorithm (mcccga): Applies machine-coded compact GA to a cellular structure for optimizing real-valued problems.
• Customizable: Offers various customization options to adapt to different optimization problems.

Installation

You can install pycellga via pip:

pip install pycellga

Documentation

For full documentation, visit here or click the badge below:

Usage Examples

In this section, we'll explain cga method in the optimizer and provide an example of how to use it. The package includes various ready-to-use crossover and mutation operators, along with real-valued, binary, and permutation functions that you can run directly. Examples for other methods are available in the example folder, while an example for cga is provided below.

cga (Cellular Genetic Algorithm)

cga is a type of genetic algorithm where the population is structured as a grid (or other topologies), and each individual interacts only with its neighbors. This structure helps maintain diversity in the population and can prevent premature convergence. To specialize the CGA for real-valued optimization problems, ICGA (Improved CGA) with machine-coded representation can be used, applying byte operators. The encoding and decoding of numbers follow the IEEE 754 standard for floating-point arithmetic, yielding better results for continuous functions.

Example Problem

Suppose we have a problem that we want to minimize using a Cellular Genetic Algorithm (CGA). The problem is defined as a simple sum of squares function, where the goal is to find a chromosome (vector) that minimizes the function.

The sum of squares function computes the sum of the squares of each element in the chromosome. This function reaches its global minimum when all elements of the chromosome are equal to 0. The corresponding function value at this point is 0.

ExampleProblem Class

Here’s how we can define this problem in Python using the ExampleProblem class:

from mpmath import power as pw
from typing import List

from pycellga.optimizer import cga
from pycellga.recombination.byte_one_point_crossover import ByteOnePointCrossover
from pycellga.mutation.byte_mutation_random import ByteMutationRandom
from pycellga.selection.tournament_selection import TournamentSelection
from pycellga.problems.abstract_problem import AbstractProblem
from pycellga.common import GeneType


class ExampleProblem(AbstractProblem):

    def __init__(self, n_var):

        super().__init__(
            gen_type=GeneType.REAL,
            n_var=n_var,
            xl=-100, 
            xu=100
        )

    def f(self, x: List[float]) -> float:
        return round(sum(pw(xi, 2) for xi in x),3)

Usage:

result = cga(
        n_cols=5,
        n_rows=5,
        n_gen=100,
        ch_size=5,
        p_crossover=0.9,
        p_mutation=0.2,
        problem=ExampleProblem(n_var=5),
        selection=TournamentSelection,
        recombination=ByteOnePointCrossover,
        mutation=ByteMutationRandom,
        seed_par=100
    )

    # Print the results
    print("Best solution chromosome:", result.chromosome)
    print("Best fitness value:", result.fitness_value)

# Expected Output:
# Best solution chromosome: [0.0, 0.0, 0.0, 0.0, 0.0]
# Best fitness value: 0.0

We have provided a basic example above. If you're interested in exploring more examples, you have two options:

• Click here to see the other examples available directly in the repository.
• Please click here to see the documentation for more detailed examples and explanations.

Contributing

Contributions are welcome! Please read the contributing guidelines first.

Testing

To ensure that pycellga works as expected, we have provided a comprehensive suite of tests. Follow these steps to run the tests locally:

1. Install dependencies: Make sure you have installed all the necessary dependencies from requirements.txt. You can install them using the following command:

   pip install -r requirements.txt

2. Run tests: Navigate to the root directory of the project and run the test suite using pytest.

   pytest

   This will automatically discover and execute all the test cases.

3. Check code coverage (Optional): You can check the test coverage of the package using pytest-cov. First, ensure you have installed pytest-cov:

   pip install pytest-cov

   Then, run the tests with coverage reporting:

   pytest --cov=pycellga

   A summary of code coverage will be displayed in the terminal.

4. Generate coverage reports: If you want a detailed HTML report of the code coverage, run:

   pytest --cov=pycellga --cov-report=html

   Open the htmlcov/index.html file in a web browser to view the detailed coverage report.

5. Add new tests (if applicable):

   • If your changes introduce new features or modify existing functionality, write additional test cases to cover these changes.
   • Place your tests in the appropriate subdirectory within the tests folder, following the naming convention test_<feature_name>.py.

6. Review testing guidelines:

   • Ensure your tests follow the existing style and structure used in the project. Use descriptive function names and provide comments where necessary to clarify the test's purpose.

License

This project is licensed under the MIT License - see the LICENSE file for details.

Acknowledgements

Developed by Sevgi Akten Karakaya and Mehmet Hakan Satman. Inspired by traditional genetic algorithms and cellular automata principles with machine coded operators. For more information, please visit the project repository.

Citation

If you use pycellga in your research, please cite it as follows:

APA Format

Karakaya, S. A., & Satman, M. H. (2024). An Improved Cellular Genetic Algorithm with Machine-Coded Operators for Real-Valued Optimisation Problems. Journal of Engineering Research and Applied Science, 13(1), 2500-2514.

BibTeX Format

For LaTeX users, please use the following BibTeX entry to cite pycellga:

@article{karakaya2024improved,
  title={An Improved Cellular Genetic Algorithm with Machine-Coded Operators for Real-Valued Optimisation Problems},
  author={Karakaya, Sevgi Akten and Satman, Mehmet Hakan},
  journal={Journal of Engineering Research and Applied Science},
  volume={13},
  number={1},
  pages={2500--2514},
  year={2024}
}