refact: move selection_rate & mutation_rate out from GAParams t…

…o operators (#478)

## Description

## Linked issues <!-- Please use "Resolves #<issue_no> syntax in case
this PR should be linked to an issue -->

Closes #477
Closes kkafar/master-monorepo#246

## Important implementation details <!-- if any, optional section -->

coco/src/main.rs

@@ -120,7 +120,7 @@ fn ecrs_ga_search(problem: &mut Problem, _max_budget: usize, _random_generator:
     ))
     .set_selection_operator(selection::Tournament::new(0.2))
     .set_crossover_operator(crossover::Uniform::new())
-    .set_mutation_operator(mutation::Reversing::new())
+    .set_mutation_operator(mutation::Reversing::new(0.05))
     .set_replacement_operator(replacement::WeakParent::new())
     .build();
 

src/ga.rs

@@ -143,8 +143,8 @@ use self::{
 };
 
 pub struct GAParams {
-    pub selection_rate: f64,
-    pub mutation_rate: f64,
+    // pub selection_rate: f64,
+    // pub mutation_rate: f64,
     pub population_size: usize,
     pub generation_limit: usize,
     pub max_duration: std::time::Duration,
@@ -322,11 +322,9 @@ where
             self.metadata.crossover_dur = Some(self.timer.elapsed());
 
             self.timer.start();
-            children.iter_mut().for_each(|child| {
-                self.config
-                    .mutation_operator
-                    .apply(&self.metadata, child, self.config.params.mutation_rate)
-            });
+            children
+                .iter_mut()
+                .for_each(|child| self.config.mutation_operator.apply(&self.metadata, child));
             self.metadata.mutation_dur = Some(self.timer.elapsed());
 
             if self.config.replacement_operator.requires_children_fitness() {

src/ga/builder.rs

@@ -64,8 +64,6 @@ impl Error for ConfigError {}
 // don't have to write it by hand...
 #[derive(Debug, Clone)]
 pub struct GAParamsOpt {
-    pub selection_rate: Option<f64>,
-    pub mutation_rate: Option<f64>,
     pub population_size: Option<usize>,
     pub generation_limit: Option<usize>,
     pub max_duration: Option<std::time::Duration>,
@@ -75,8 +73,6 @@ impl GAParamsOpt {
     /// Returns new instance of [GAParamsOpt] struct. All fields are `None` initially.
     pub fn new() -> Self {
         Self {
-            selection_rate: None,
-            mutation_rate: None,
             population_size: None,
             generation_limit: None,
             max_duration: None,
@@ -85,8 +81,6 @@ impl GAParamsOpt {
 
     /// Sets all `None` values to values form `other`
     pub fn fill_from(&mut self, other: &GAParams) {
-        self.selection_rate.get_or_insert(other.selection_rate);
-        self.mutation_rate.get_or_insert(other.mutation_rate);
         self.population_size.get_or_insert(other.population_size);
         self.generation_limit.get_or_insert(other.generation_limit);
         self.max_duration.get_or_insert(other.max_duration);
@@ -97,14 +91,6 @@ impl TryFrom<GAParamsOpt> for GAParams {
     type Error = ConfigError;
 
     fn try_from(params_opt: GAParamsOpt) -> Result<Self, Self::Error> {
-        let Some(selection_rate) = params_opt.selection_rate else {
-            return Err(ConfigError::MissingParam("Unspecified selection rate".to_owned()));
-        };
-
-        let Some(mutation_rate) = params_opt.mutation_rate else {
-            return Err(ConfigError::MissingParam("Unspecified mutation rate".to_owned()));
-        };
-
         let Some(population_size) = params_opt.population_size else {
             return Err(ConfigError::MissingParam(
                 "Unspecified population size".to_owned(),
@@ -122,8 +108,6 @@ impl TryFrom<GAParamsOpt> for GAParams {
         };
 
         Ok(GAParams {
-            selection_rate,
-            mutation_rate,
             population_size,
             generation_limit,
             max_duration,
@@ -313,8 +297,8 @@ impl Builder {
 /// some of the values.
 pub(crate) trait DefaultParams {
     const DEFAULT_PARAMS: GAParams = GAParams {
-        selection_rate: 1.0,
-        mutation_rate: 0.05,
+        // selection_rate: 1.0,
+        // mutation_rate: 0.05,
         population_size: 100,
         generation_limit: usize::MAX,
         max_duration: std::time::Duration::MAX,
@@ -340,8 +324,8 @@ mod test {
     #[test]
     fn new_param_opt_is_empty() {
         let params = GAParamsOpt::new();
-        assert!(params.selection_rate.is_none());
-        assert!(params.mutation_rate.is_none());
+        // assert!(params.selection_rate.is_none());
+        // assert!(params.mutation_rate.is_none());
         assert!(params.population_size.is_none());
         assert!(params.generation_limit.is_none());
         assert!(params.max_duration.is_none());
@@ -350,21 +334,16 @@ mod test {
     #[test]
     fn param_opt_fills_correctly() {
         let mut params_opt = GAParamsOpt::new();
-        params_opt.selection_rate = Some(0.5);
         params_opt.generation_limit = Some(100);
 
         let params = GAParams {
-            selection_rate: 1.0,
-            mutation_rate: 1.0,
             population_size: 100,
             generation_limit: 200,
             max_duration: std::time::Duration::from_secs(1),
         };
 
         params_opt.fill_from(&params);
 
-        assert!(params_opt.selection_rate.is_some() && params_opt.selection_rate.unwrap() == 0.5);
-        assert!(params_opt.mutation_rate.is_some() && params_opt.mutation_rate.unwrap() == 1.0);
         assert!(params_opt.population_size.is_some() && params_opt.population_size.unwrap() == 100);
         assert!(params_opt.generation_limit.is_some() && params_opt.generation_limit.unwrap() == 100);
         assert!(
@@ -377,12 +356,6 @@ mod test {
     fn conversion_works_as_expected() {
         let mut params_opt = GAParamsOpt::new();
 
-        params_opt.selection_rate = Some(1.0);
-        assert!(convert_gaparamsopt_to_ga_params(params_opt.clone()).is_err());
-
-        params_opt.mutation_rate = Some(0.0);
-        assert!(convert_gaparamsopt_to_ga_params(params_opt.clone()).is_err());
-
         params_opt.population_size = Some(200);
         assert!(convert_gaparamsopt_to_ga_params(params_opt.clone()).is_err());
 

src/ga/builder/bitstring.rs

@@ -57,28 +57,6 @@ impl<F: Fitness<BitStringIndividual>> BitStringBuilder<F> {
         }
     }
 
-    /// Sets selection rate
-    ///
-    /// ## Arguments
-    ///
-    /// * `selection_rate` - Selection rate; must be in [0, 1] interval
-    pub fn set_selection_rate(mut self, selection_rate: f64) -> Self {
-        assert!((0f64..=1f64).contains(&selection_rate));
-        self.config.params.selection_rate = Some(selection_rate);
-        self
-    }
-
-    /// Sets mutation rate
-    ///
-    /// ## Arguments
-    ///
-    /// * `mutation_rate` - Mutation rate; must be in [0, 1] interval
-    pub fn set_mutation_rate(mut self, mutation_rate: f64) -> Self {
-        assert!((0.0..=1.0).contains(&mutation_rate));
-        self.config.params.mutation_rate = Some(mutation_rate);
-        self
-    }
-
     /// Sets max duration. If exceeded, the algorithm halts.
     ///
     /// ## Arguments
@@ -167,7 +145,9 @@ impl<F: Fitness<BitStringIndividual>> BitStringBuilder<F> {
         self.config
             .crossover_operator
             .get_or_insert_with(SinglePoint::new);
-        self.config.mutation_operator.get_or_insert_with(FlipBit::new);
+        self.config
+            .mutation_operator
+            .get_or_insert_with(|| FlipBit::new(0.05));
         self.config
             .selection_operator
             .get_or_insert_with(|| Tournament::new(0.2));

src/ga/builder/generic.rs

@@ -75,36 +75,6 @@ where
         }
     }
 
-    /// Sets selection rate
-    ///
-    /// ## Arguments
-    ///
-    /// * `selection_rate` - Selection rate; must be in [0, 1] interval
-    ///
-    /// ## Panics
-    ///
-    /// If the `selection_rate` param has invalid value.
-    pub fn set_selection_rate(mut self, selection_rate: f64) -> Self {
-        assert!((0f64..=1f64).contains(&selection_rate));
-        self.config.params.selection_rate = Some(selection_rate);
-        self
-    }
-
-    /// Sets mutation rate
-    ///
-    /// ## Arguments
-    ///
-    /// * `mutation_rate` - Mutation rate; must be in [0, 1] interval
-    ///
-    /// ## Panics
-    ///
-    /// If the parameter has invalid value.
-    pub fn set_mutation_rate(mut self, mutation_rate: f64) -> Self {
-        assert!((0.0..=1.0).contains(&mutation_rate));
-        self.config.params.mutation_rate = Some(mutation_rate);
-        self
-    }
-
     /// Sets max duration. If exceeded, the algorithm halts.
     ///
     /// ## Arguments

src/ga/builder/realvalued.rs

@@ -56,28 +56,6 @@ impl<F: Fitness<RealValueIndividual>> RealValuedBuilder<F> {
         }
     }
 
-    /// Sets selection rate
-    ///
-    /// ## Arguments
-    ///
-    /// * `selection_rate` - Selection rate; must be in [0, 1] interval
-    pub fn set_selection_rate(mut self, selection_rate: f64) -> Self {
-        debug_assert!((0f64..=1f64).contains(&selection_rate));
-        self.config.params.selection_rate = Some(selection_rate);
-        self
-    }
-
-    /// Sets mutation rate
-    ///
-    /// ## Arguments
-    ///
-    /// * `mutation_rate` - Mutation rate; must be in [0, 1] interval
-    pub fn set_mutation_rate(mut self, mutation_rate: f64) -> Self {
-        assert!((0.0..=1.0).contains(&mutation_rate));
-        self.config.params.mutation_rate = Some(mutation_rate);
-        self
-    }
-
     /// Sets max duration. If exceeded, the algorithm halts.
     ///
     /// ## Arguments
@@ -166,7 +144,9 @@ impl<F: Fitness<RealValueIndividual>> RealValuedBuilder<F> {
         self.config
             .crossover_operator
             .get_or_insert_with(SinglePoint::new);
-        self.config.mutation_operator.get_or_insert_with(Interchange::new);
+        self.config
+            .mutation_operator
+            .get_or_insert_with(|| Interchange::new(0.05));
         self.config
             .selection_operator
             .get_or_insert_with(|| Tournament::new(0.2));

src/ga/operators/mutation.rs

@@ -16,5 +16,5 @@ pub trait MutationOperator<IndividualT: IndividualTrait> {
     ///
     /// * `individual` - mutable reference to to-be-mutated individual
     /// * `mutation_rate` - probability of gene mutation
-    fn apply(&mut self, metadata: &GAMetadata, individual: &mut IndividualT, mutation_rate: f64);
+    fn apply(&mut self, metadata: &GAMetadata, individual: &mut IndividualT);
 }