1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135

//! This module contains the Crossover trait and the provided crossover functions.

use genotype::Genotype;
use rand::distributions::Uniform;
use rand::prelude::*;
use std::cmp::{min, PartialEq};
use CrossoverFunctions::*;

/// This trait defines the cross function.
pub trait Crossover<T: PartialEq, G: Genotype<T>>: Send + Sync {
    /// Generates two children combining the two selected individuals.
    fn cross(&self, ind1: &G, ind2: &G) -> (G, G);
}

/// Provided crossover functions.
#[derive(Debug)]
pub enum CrossoverFunctions {
    /// Single point Crossover.
    SingleCrossPoint,
    /// Multi point Crossover.
    MultiCrossPoint,
    /// Uniform Crossover.
    UniformCross,
}

impl<T: PartialEq, G: Genotype<T>> Crossover<T, G> for CrossoverFunctions {
    fn cross(&self, ind1: &G, ind2: &G) -> (G, G) {
        match self {
            SingleCrossPoint => {
                let ind_size = min(ind1.iter().len(), ind2.iter().len());
                let cross_point = SmallRng::from_entropy().sample(Uniform::from(1..ind_size));

                let mut child1 = ind1.clone();
                child1.from_iter(
                    ind1.clone()
                        .into_iter()
                        .zip(ind2.clone().into_iter())
                        .enumerate()
                        .map(|(i, (gen1, gen2))| if i < cross_point { gen1 } else { gen2 }),
                );
                let mut child2 = ind2.clone();
                child2.from_iter(
                    ind1.clone()
                        .into_iter()
                        .zip(ind2.clone().into_iter())
                        .enumerate()
                        .map(|(i, (gen1, gen2))| if i < cross_point { gen2 } else { gen1 }),
                );

                (child1, child2)
            }
            MultiCrossPoint => {
                let ind_size = min(ind1.iter().len(), ind2.iter().len());
                let mut cross_points = Vec::new();
                let mut point_maximum = ind_size / 2;
                if point_maximum <= 2 {
                    point_maximum = 3;
                }
                let mut i = SmallRng::from_entropy().sample(Uniform::from(1..point_maximum));
                while i < ind_size {
                    cross_points.push(i);
                    i += SmallRng::from_entropy().sample(Uniform::from(1..point_maximum));
                }
                cross_points.push(ind_size);

                let mut child1 = ind1.clone();
                child1.from_iter(
                    ind1.clone()
                        .into_iter()
                        .zip(ind2.clone().into_iter())
                        .enumerate()
                        .map(|(i, (gen1, gen2))| {
                            let mut even = false;
                            for cross_point in &cross_points {
                                if i < *cross_point {
                                    if even {
                                        return gen2;
                                    } else {
                                        return gen1;
                                    }
                                } else {
                                    even = !even;
                                }
                            }
                            gen1
                        }),
                );
                let mut child2 = ind2.clone();
                child2.from_iter(
                    ind1.clone()
                        .into_iter()
                        .zip(ind2.clone().into_iter())
                        .enumerate()
                        .map(|(i, (gen1, gen2))| {
                            let mut even = false;
                            for cross_point in &cross_points {
                                if i < *cross_point {
                                    if even {
                                        return gen1;
                                    } else {
                                        return gen2;
                                    }
                                } else {
                                    even = !even;
                                }
                            }
                            gen2
                        }),
                );

                (child1, child2)
            }
            UniformCross => {
                let mut child1 = ind1.clone();
                child1.from_iter(
                    ind1.clone()
                        .into_iter()
                        .zip(ind2.clone().into_iter())
                        .enumerate()
                        .map(|(i, (gen1, gen2))| if i % 2 == 0 { gen1 } else { gen2 }),
                );
                let mut child2 = ind2.clone();
                child2.from_iter(
                    ind1.clone()
                        .into_iter()
                        .zip(ind2.clone().into_iter())
                        .enumerate()
                        .map(|(i, (gen1, gen2))| if i % 2 != 0 { gen1 } else { gen2 }),
                );

                (child1, child2)
            }
        }
    }
}