genetic_algorithms 3.0.0

Library for solving genetic algorithm problems
Documentation 
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//! Swap mutation operator.
//!
//! Selects two random positions in a chromosome's DNA and exchanges their
//! genes. This is one of the simplest mutation operators and works with any
//! chromosome type.

use crate::traits::LinearChromosome;
pub(crate) use rand::Rng;

/// Swap mutation: randomly selects two positions in the chromosome and
/// exchanges their genes.
///
/// This operator preserves all alleles (no values are created or destroyed),
/// making it suitable for both value-encoded and permutation-encoded
/// chromosomes. If the DNA has fewer than 2 genes the function is a no-op.
///
/// # Examples
///
/// ```rust,no_run
/// use genetic_algorithms::operations::mutation::swap;
/// use genetic_algorithms::chromosomes::Binary;
/// let mut chromosome = Binary::new();
/// swap(&mut chromosome);
/// ```
pub fn swap<U: LinearChromosome>(chromosome: &mut U) {
    //Getting two random genes from the dna of the chromosome
    crate::log_debug!(target="mutation_events", method="swap"; "Starting the swap mutation");
    if chromosome.dna().len() < 2 {
        return;
    }
    let mut rng = crate::rng::make_rng();
    let index_1 = rng.random_range(0..chromosome.dna().len());
    let index_2 = rng.random_range(0..chromosome.dna().len());
    crate::log_trace!(target="mutation_events", method="swap"; "Mutation index 1: {}, mutation index 2: {}", index_1, index_2);

    //Swapping both genes in-place
    chromosome.dna_mut().swap(index_1, index_2);
    crate::log_debug!(target="mutation_events", method="swap"; "Swap mutation finished");
}