Selection Operators Reference

Selection operators choose parents for reproduction.

Module

use fugue_evo::operators::selection::{
    TournamentSelection, RouletteWheelSelection, RankSelection
};

Tournament Selection

Select best from k random individuals.

let selection = TournamentSelection::new(k);

Characteristics:

• Higher k = more selection pressure
• k=2 is minimal pressure
• k=5-7 for high pressure
• Efficient: O(k) per selection

Example:

let selection = TournamentSelection::new(3);
// Selects best of 3 random individuals

Roulette Wheel Selection

Probability proportional to fitness.

let selection = RouletteWheelSelection::new();

Characteristics:

• Fitness proportionate
• Can lose selection pressure with similar fitnesses
• Sensitive to fitness scaling
• O(n) setup, O(log n) per selection

Requirements:

• Fitness must be positive
• Works best with transformed fitness

Rank Selection

Probability based on fitness rank.

let selection = RankSelection::new();
// or with pressure parameter
let selection = RankSelection::with_pressure(2.0);

Characteristics:

• Robust to fitness scaling
• Maintains selection pressure
• O(n log n) for ranking
• Good for multimodal problems

Comparison

Usage

SimpleGABuilder::<RealVector, f64, _, _, _, _, _>::new()
    .selection(TournamentSelection::new(3))
    // ...

See Also

• Custom Operators - Create custom selection