genetic_algorithms (v2.0.0)

Modular and concurrent Genetic Algorithms (GA) library for Rust featuring:

• Clear abstractions (traits for genes, chromosomes, and configuration).
• Composable operators (selection, crossover, mutation, survivor).
• Multi-threaded execution via rayon (fitness evaluation, reproduction, mutation in parallel).
• Adaptive GA mode (dynamic crossover and mutation probabilities based on population performance).
• Elitism support (preserve top N individuals across generations).
• Compound stopping criteria (stagnation, convergence, time limit).
• Cow for minimizing unnecessary DNA copies.

Table of Contents

• Documentation
• Changelog
• Status & Key Changes 2.0.0
• Features
  • Traits
  • Included Genotypes & Chromosomes
  • Initializers
  • Operators
  • GA Configuration
  • Adaptive GA
  • Multithreading & Performance
• Quick Example
• Full Example (Range)
• Usage
• Development
• Roadmap / Notes
• License

Documentation

Latest published docs: docs.rs/genetic_algorithms

Status & Key Changes 2.0.0

Main differences vs 1.x:

• Crate version: 2.0.0 (update your Cargo.toml).
• Structured error handling: all operators return Result<T, GaError> instead of panicking.
• Parallelism via rayon replacing manual thread management.
• GeneT::get_id() now returns i32 directly.
• ChromosomeT::set_dna now uses Cow<'a, [Gene]> to avoid redundant copies.
• Added Range<T> genotype alongside Binary (supports numeric ranges).
• New operators: SinglePoint, Order (OX), BitFlip, Value, Creep, Gaussian mutations; SBX, BlendAlpha crossovers; Rank selection.
• Elitism: with_elitism(n) preserves the top N individuals across generations.
• Compound stopping criteria: stagnation detection, convergence threshold, time limit.
• Per-generation statistics tracking via GenerationStats.
• Adaptive probability helpers: aga_probability for crossover & mutation.
• Expanded configuration: FixedFitness, logging levels (Off..Trace), configurable threads.
• Internal benchmarks use Criterion 0.7 (pprof integration removed due to version conflict).

Features

Traits

• GeneT:
  • Requires: Default + Clone + Send + Sync.
  • Key methods: new(), get_id() -> i32, set_id(i32).
• ChromosomeT:
  • Associated: type Gene: GeneT.
  • Supports: get_dna(), set_dna(Cow<[Gene]>), set_gene(idx, gene), set_fitness_fn(...), calculate_fitness(), get_fitness(), set_fitness(f64), get_age(), set_age(i32).
  • Derived metric: get_fitness_distance(&fitness_target).
• ConfigurationT: builder-style API for Ga / GaConfiguration.

Included Genotypes & Chromosomes

• genotypes::Binary (boolean gene).
• genotypes::Range<T> (values constrained to one or more (min,max) intervals).
• chromosomes::Range<T> (chromosome built from Range<T> genes).
• (Custom chromosomes can be added by implementing ChromosomeT).

Initializers

• initializers::binary_random_initialization.
• initializers::range_random_initialization.
• initializers::generic_random_initialization (takes allele slice, optional unique IDs).
• initializers::generic_random_initialization_without_repetitions (no allele repetition).

Operators

• Selection: Random, RouletteWheel, StochasticUniversalSampling, Tournament, Rank.
• Crossover: Cycle, MultiPoint, Uniform, SinglePoint, Order (OX), Sbx (Simulated Binary), BlendAlpha (BLX-α).
• Mutation: Swap, Inversion, Scramble, Value (Range), BitFlip (Binary), Creep (uniform perturbation), Gaussian (normal perturbation).
• Survivor: Fitness (keep best), Age (prefer younger / age-based pruning).

GA Configuration

GaConfiguration (or the Ga builder) exposes:

• Limits: problem_solving (Minimization | Maximization | FixedFitness), max_generations, fitness_target, population_size, genes_per_chromosome, needs_unique_ids, alleles_can_be_repeated.
• Selection: number_of_couples, method.
• Crossover: number_of_points (MultiPoint), probability_min / probability_max, method, sbx_eta (SBX distribution index), blend_alpha (BLX-α alpha parameter).
• Mutation: probability_min / probability_max, method, step (Creep step size), sigma (Gaussian standard deviation).
• Survivor: survivor.
• Elitism: elitism_count — preserve the top N individuals unchanged across generations.
• Stopping criteria: StoppingCriteria with stagnation_generations, convergence_threshold, max_duration_secs. The GA stops when any enabled criterion is met.
• Infra: adaptive_ga, number_of_threads, log_level.
• Progress (present but not yet wired): save_progress_configuration (future/experimental).

Adaptive GA

When adaptive_ga = true:

• Crossover & mutation probabilities are recomputed per parent pair using relative fitness (f_max, f_avg).
• You must set both probability_min and probability_max for crossover and mutation. When adaptive_ga = false:
• If probability_max is absent, defaults to 1.0 (operator always applied).

Multithreading & Performance

• with_threads(n) configures parallelism (internally uses rayon).
• Selection, crossover, mutation, and fitness evaluation are parallelized each generation.
• Cow prevents needless cloning of DNA vectors.

Quick Example

Minimal GA using Range<i32> chromosomes targeting fitness 0 (minimization):

use genetic_algorithms::ga::Ga;
use genetic_algorithms::traits::ConfigurationT;
use genetic_algorithms::configuration::ProblemSolving;
use genetic_algorithms::operations::{Selection, Crossover, Mutation, Survivor};
use genetic_algorithms::genotypes::Range as RangeGene;
use genetic_algorithms::initializers::range_random_initialization;
use genetic_algorithms::chromosomes::Range as RangeChromosome; // Chromosome type

fn fitness_fn(dna: &[RangeGene<i32>]) -> f64 { // Replace with domain logic
    dna.iter().map(|g| g.get_value() as f64).sum() // Simple example
}

let alleles = vec![RangeGene::new(0, vec![(0, 7)], 0)];
let alleles_clone = alleles.clone();
let mut ga = Ga::<RangeChromosome<i32>>::new();
let _population = ga
    .with_genes_per_chromosome(8)
    .with_population_size(100)
    .with_initialization_fn(move |genes, _, _| {
        range_random_initialization(genes, Some(&alleles_clone), Some(false))
    })
    .with_fitness_fn(fitness_fn)
    .with_selection_method(Selection::Tournament)
    .with_crossover_method(Crossover::Uniform)
    .with_mutation_method(Mutation::Swap)
    .with_survivor_method(Survivor::Fitness)
    .with_problem_solving(ProblemSolving::Minimization)
    .with_max_generations(500)
    .with_fitness_target(0.0)
    .with_threads(4)
    .run();

Full Example (Range)

Includes adaptive GA and probabilities:

use genetic_algorithms::{ga::Ga, traits::ConfigurationT};
use genetic_algorithms::configuration::ProblemSolving;
use genetic_algorithms::operations::{Selection, Crossover, Mutation, Survivor};
use genetic_algorithms::genotypes::Range as RangeGene;
use genetic_algorithms::chromosomes::Range as RangeChromosome;
use genetic_algorithms::initializers::range_random_initialization;

fn fitness_fn(dna: &[RangeGene<i32>]) -> f64 {
    // Penalize greater values: minimization goal
    dna.iter().map(|g| g.get_value() as f64).sum()
}

let alleles = vec![RangeGene::new(0, vec![(0, 50)], 0)];
let alleles_clone = alleles.clone();
let mut ga = Ga::<RangeChromosome<i32>>::new();
let population = ga
    .with_adaptive_ga(true)
    .with_genes_per_chromosome(16)
    .with_population_size(200)
    .with_initialization_fn(move |genes, _, _| {
        range_random_initialization(genes, Some(&alleles_clone), Some(false))
    })
    .with_fitness_fn(fitness_fn)
    .with_selection_method(Selection::StochasticUniversalSampling)
    .with_crossover_method(Crossover::MultiPoint)
    .with_crossover_number_of_points(3)
    .with_crossover_probability_min(0.4)
    .with_crossover_probability_max(0.9)
    .with_mutation_method(Mutation::Inversion)
    .with_mutation_probability_min(0.05)
    .with_mutation_probability_max(0.3)
    .with_survivor_method(Survivor::Fitness)
    .with_problem_solving(ProblemSolving::Minimization)
    .with_max_generations(2000)
    .with_fitness_target(0.0)
    .with_threads(8)
    .with_logs(genetic_algorithms::configuration::LogLevel::Info)
    .run();

println!("Best fitness: {}", population.unwrap().best_chromosome.get_fitness());

Usage

Add to your Cargo.toml:

[dependencies]
genetic_algorithms = "2.0.0"

Development

Build

cargo build            # Debug build
cargo build --release  # Optimized release build

Run Tests

cargo test                        # Run all tests (unit + integration + doc-tests)
cargo test test_ga                # Run only tests matching "test_ga"
cargo test -- --nocapture         # Run tests with visible stdout/stderr
cargo test --doc                  # Run doc-tests only

Run Benchmarks

Benchmarks use Criterion and are located in benches/.

cargo bench                       # Run all benchmarks
cargo bench --bench crossover     # Run only crossover benchmarks
cargo bench --bench mutation      # Run only mutation benchmarks
cargo bench --bench selection     # Run only selection benchmarks
cargo bench --bench survivor      # Run only survivor benchmarks
cargo bench --no-run              # Only compile benchmarks (useful for CI)

Reports are generated in target/criterion/ and can be viewed in a browser.

Run Examples

cargo run --example knapsack_binary   # 0/1 Knapsack problem using Binary chromosomes
cargo run --example nqueens_range     # N-Queens problem using Range<i32> chromosomes

Code Quality

cargo fmt --check   # Check formatting (no changes)
cargo fmt           # Auto-format code
cargo clippy        # Run linter

Roadmap / Notes

• save_progress_configuration: fields present but not wired into the main loop yet (future: periodic population / best chromosome persistence).
• Optional flamegraph profiling integration removed to avoid Criterion version conflicts.
• For heavy fitness functions consider external profiling tools.

License

Apache-2.0. See LICENSE file.