coords-nsga2 2.4.0

A Python library implementing a coordinate-based NSGA-II for multi-objective optimization.

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A Python library implementing a coordinate-based NSGA-II (Non-dominated Sorting Genetic Algorithm II) for multi-objective optimization. This library is specifically designed for optimizing coordinate point layouts, featuring specialized constraints, crossover, and mutation operators that work directly on coordinate points.

Features

• Coordinate-focused optimization: Designed specifically for optimizing layouts of coordinate points
• Variable point count support: Supports both fixed number of points and dynamic point count within a specified range
• Multi-objective optimization: Supports 2 or more objective functions using NSGA-II algorithm
• Parallel computation: Accelerate optimization with parallel processing for computationally intensive problems
• Specialized constraints: Built-in support for point spacing, boundary limits, and custom constraints
• Tailored genetic operators: Custom crossover and mutation operators that directly act on coordinate points
• Flexible region definition: Support for both polygon and rectangular regions
• Lightweight and extensible: Easy to customize operators and constraints
• Progress tracking: Built-in progress bars and optimization history
• Save/Load functionality: Save and restore optimization states

Installation

From PyPI

pip install coords-nsga2

From Source

git clone https://github.com/ZXF1001/coords-nsga2.git
cd coords-nsga2
pip install -e .

Quick Start

Here's a minimal example demonstrating how to run a coordinate-based NSGA-II optimization with multiple objectives:

import numpy as np
from scipy.spatial import distance
from coords_nsga2 import CoordsNSGA2, Problem
from coords_nsga2.spatial import region_from_points

# Define the optimization region
region = region_from_points([
    [0, 0],
    [1, 0],
    [2, 1],
    [1, 1],
])

# Define objective functions
def objective_1(coords):
    """Maximize sum of x and y coordinates"""
    return np.sum(coords[:, 0]) + np.sum(coords[:, 1])

def objective_2(coords):
    """Maximize spread of points"""
    return np.std(coords[:, 0]) + np.std(coords[:, 1])

# Define constraints
spacing = 0.05
def constraint_1(coords):
    """Minimum spacing between points"""
    dist_list = distance.pdist(coords)
    penalty_list = spacing - dist_list[dist_list < spacing]
    return np.sum(penalty_list)

# Setup the problem
problem = Problem(
    objectives=[objective_1, objective_2],  # List of objective functions
    n_points=[10, 30],  # Can be fixed number or range [min, max]
    region=region,
    constraints=[constraint_1]
)

# Initialize the optimizer
optimizer = CoordsNSGA2(
    problem=problem,
    pop_size=20,
    prob_crs=0.5,
    prob_mut=0.1
)

# Run optimization
result = optimizer.run(1000)

# Visualize optimal layouts for each objective
optimizer.plot.optimal_coords(obj_indices=0)

# Access results
print(f"Result shape: {result.shape}")
print(f"Number of objectives: {len(optimizer.values_P)}")
print(f"Optimization history length: {len(optimizer.P_history)}")

Documentation

Complete documentation is available in the docs/ folder.

To start the documentation server locally:

mkdocs serve

To build the documentation:

mkdocs build

Contributing

Contributions are welcome! Please feel free to submit a Pull Request. For major changes, please open an issue first to discuss what you would like to change.

1. Fork the repository
2. Create your feature branch (git checkout -b feature/AmazingFeature)
3. Commit your changes (git commit -m 'Add some AmazingFeature')
4. Push to the branch (git push origin feature/AmazingFeature)
5. Open a Pull Request

License

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

Citation

If you use this library in your research, please cite:

@software{Coords-NSGA2,
  title={Coords-NSGA2: A Python library for coordinate-based multi-objective optimization},
  author={Zhang, Xiaofeng},
  year={2025},
  url={https://github.com/ZXF1001/coords-nsga2}
}