Struct vrp_core::solver::Builder

pub struct Builder {
    pub max_generations: Option<usize>,
    pub max_time: Option<usize>,
    pub cost_variation: Option<(usize, f64)>,
    pub seed: Option<u64>,
    pub config: EvolutionConfig,
}

Provides configurable way to build Vehile Routing Problem Solver instance using fluent interface style.

A newly created builder instance is pre-configured with some reasonable defaults for mid-size problems (~200), so there is no need to call any of its methods.

Examples

This example shows how to override some of default metaheuristic parameters using fluent interface methods:

use vrp_core::solver::Builder;
use vrp_core::models::Problem;

// create your VRP problem
let problem: Arc<Problem> = create_example_problem();
// build solver using builder with overridden parameters
let solver = Builder::new(problem)
    .with_max_time(Some(60))
    .with_max_generations(Some(100))
    .build()?;
// run solver and get the best known solution within its cost.
let (solution, cost, _) = solver.solve()?;

assert_eq!(cost, 42.);
assert_eq!(solution.routes.len(), 1);
assert_eq!(solution.unassigned.len(), 0);

Fields

max_generations: Option<usize>

A max amount generations in evolution.

max_time: Option<usize>

A max seconds to run evolution.

cost_variation: Option<(usize, f64)>

A cost variation parameters for termination criteria.

seed: Option<u64>

A randomization seed

config: EvolutionConfig

An evolution configuration..

Implementations

impl Builder

pub fn new(problem: Arc<Problem>) -> Self

Creates a new instance of Builder.

impl Builder

pub fn with_telemetry(self, telemetry: Telemetry) -> Self

Sets telemetry. Default telemetry is set to do nothing.

pub fn with_max_generations(self, limit: Option<usize>) -> Self

Sets max generations to be run by evolution. Default is 3000.

pub fn with_cost_variation(self, variation: Option<(usize, f64)>) -> Self

Sets cost variation termination criteria. Default is None.

pub fn with_max_time(self, limit: Option<usize>) -> Self

Sets max running time limit for evolution. Default is 300 seconds.

pub fn with_init_params(
    self,
    size: Option<usize>,
    initial_methods: Option<Vec<(Box<dyn Recreate + Send + Sync>, usize)>>
) -> Self

Sets initial parameters used to construct initial population.

pub fn with_init_solutions(self, solutions: Vec<Solution>) -> Self

Sets initial solutions in population. Default is no solutions in population.

pub fn with_population_size(self, size: usize) -> Self

Sets max population size. Default is 4.

pub fn with_selection(self, selection: Arc<dyn Selection + Send + Sync>) -> Self

Sets selection algorithm. Default is naive selection.

pub fn with_mutation(self, mutation: Arc<dyn Mutation + Send + Sync>) -> Self

Sets mutation algorithm. Default is ruin and recreate.

pub fn with_termination(self, termination: Arc<dyn Termination>) -> Self

Sets termination algorithm. Default is max time and max generations.

pub fn with_seed(self, seed: Option<u64>) -> Self

Sets randomization seed.

pub fn build(self) -> Result<Solver, String>

Builds Solver instance.