Struct Solver

pub struct Solver<S, C> { /* private fields */ }

Parallel solver for multidimensional problems.

Usual workflow:

• Solver::new
• Solver::set_speed_factor
• Pass result of Solver::random_specimens to Solver::extend_specimens
• In a loop:
  • Inspect first element (or more elements) of Solver::specimens, e.g. for a break condition
  • Pass result of Solver::recombined_specimens to Solver::replace_worst_specimens
• Extract best specimen, e.g. using Solver::into_specimen

See module level documentation for a code example.

Implementations

impl<S, C> Solver<S, C>

pub fn new<T>(search_space: Vec<SearchRange>, constructor: C) -> Self

where C: Fn(Vec<f64>) -> T + Sync,

Create Solver for search space and Specimen constructor closure.

The closure takes a Vec<f64> as argument, which contains the coefficients/parameters, and it returns an S: Specimen. See module level documentation for a code example.

Alternatively, Futures or Results may be returned by the closure. Note that when the closure returns Futures, then the methods extend_specimens_async and replace_worst_specimens_async must be used instead of their synchronous equivalents.

pub fn dim(&self) -> usize

Dimensionality of search space.

pub fn set_division_count(&mut self, division_count: usize)

Simplify calculation by dividing dimensions into a given number of groups.

Divides dimensions into (almost) equally sized groups when calculating covariances to reduce computation time. The number of groups is given as an integer.

See Solver::set_speed_factor for a high-level interface.

pub fn set_speed_factor(&mut self, speed_factor: f64)

Simplify calculation by dividing dimensions according to speed factor.

This method is a high-level interface for Solver::set_division_count.

Uses a speed_factor to divide dimensions into (almost) equally sized groups when calculating covariances to reduce computation time. Higher speed factors generally result in faster (but possibly inaccurate) calculation.

Speed factors range from 0.0 to 1.0, however, a factor greater than 0.75 is not recommended due to the introduced overhead.

pub fn set_max_division_size(&mut self, max_division_size: usize)

Simply calculation by dividing dimensions into groups of specified maximum size.

This method is an alternative interface for Solver::set_division_count where the maximum size of each division is specified. See Solver::set_speed_factor for a high-level interface.

pub fn division_count(&self) -> usize

Number of groups into which dimensions are split when calculating covariances.

pub fn min_population(&self) -> usize

Minimum required population.

The number depends on the number of dimensions and the number of groups into which the dimensions are split when calculating covariances.

impl<S, C> Solver<S, C>

where S: Specimen + Send,

pub fn extend_specimens<I: IntoIterator<Item = S>>(&mut self, iter: I)

Add specimens to population.

pub fn replace_worst_specimens<I: IntoIterator<Item = S>>(&mut self, iter: I)

Replace worst specimens in population.

pub async fn extend_specimens_async<F, I>(&mut self, iter: I)

where F: Future<Output = S> + Send, I: IntoIterator<Item = F>,

Add specimens to population asynchronously.

pub async fn replace_worst_specimens_async<F, I>(&mut self, iter: I)

where F: Future<Output = S> + Send, I: IntoIterator<Item = F>,

Replace worst specimens in population asynchronously.

pub fn truncate_specimens(&mut self, count: usize)

Truncate population of specimens to given count (drops worst fitting specimens).

pub fn converged(&mut self) -> bool

Return true if specimens have converged.

Note that this method only returns true if the cost of all specimens is exactly equal. Additional, more sensitive termination conditions may be required in practice in order to avoid endless optimization.

pub fn specimens(&mut self) -> &[S]

Sorted population of Specimens as shared slice (best first).

pub fn specimens_mut(&mut self) -> &mut Vec<S>

Sorted population of Specimens as mutable Vec (best first).

The Vec may be modified and doesn’t need to be (re-)sorted by the caller after modifying.

pub fn into_specimens(self) -> Vec<S>

Consume Solver and return all Specimens, ordered by fitness (best first).

pub fn into_specimen(self) -> S

Consume Solver and return best Specimen.

impl<S, C, T> Solver<S, C>

where S: Specimen + Send + Sync, C: Fn(Vec<f64>) -> T + Sync, T: Send,

pub fn random_specimens(&self, count: usize) -> Vec<T>

Create random specimens

Note that depending on the return type of the closure passed to Solver::new, a Vec of Futures or Results may be returned.

pub fn recombined_specimens( &mut self, children_count: usize, local_factor: f64, ) -> Vec<T>

Create recombined specimens.

Note that depending on the return type of the closure passed to Solver::new, a Vec of Futures or Results may be returned.

Setting the local_factor to a value greater than 0.0 (but smaller than 1.0) selects a particular specimen with a correspondingly proportional chance to be modified. This allows performing more localized searches. A reasonable value seems to be 0.01 / self.dim() as f64.

Trait Implementations

impl<S: Clone, C: Clone> Clone for Solver<S, C>

fn clone(&self) -> Solver<S, C>

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<S: Debug, C: Debug> Debug for Solver<S, C>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.