Struct PlateauLR 

pub struct PlateauLR { /* private fields */ }

Available on crate feature alloc only.

Reduce learning rate when the loss plateaus.

Monitors current_loss and reduces the rate by factor whenever the loss has not improved for patience consecutive steps. “Improved” means the new loss is strictly less than the best-seen loss.

The rate is floored at min_lr to prevent it from vanishing entirely.

Example

use irithyll::ensemble::lr_schedule::{LRScheduler, PlateauLR};

let mut sched = PlateauLR::new(0.1, 0.5, 3, 0.001);

// Improving loss -- rate stays at 0.1.
assert!(crate::math::abs((sched.learning_rate(0, 1.0) - 0.1)) < 1e-12);
assert!(crate::math::abs((sched.learning_rate(1, 0.9) - 0.1)) < 1e-12);

// Stagnating loss for patience=3 steps.
assert!(crate::math::abs((sched.learning_rate(2, 0.95) - 0.1)) < 1e-12);
assert!(crate::math::abs((sched.learning_rate(3, 0.95) - 0.1)) < 1e-12);
assert!(crate::math::abs((sched.learning_rate(4, 0.95) - 0.1)) < 1e-12);

// Patience exhausted -- rate drops to 0.1 * 0.5 = 0.05.
assert!(crate::math::abs((sched.learning_rate(5, 0.95) - 0.05)) < 1e-12);

Implementations

impl PlateauLR

pub fn new(initial_lr: f64, factor: f64, patience: u64, min_lr: f64) -> Self

Create a plateau-aware scheduler.

Arguments

• initial_lr – Starting learning rate.
• factor – Multiplicative reduction factor (e.g., 0.5 halves the rate).
• patience – Number of non-improving steps to tolerate before reducing.
• min_lr – Floor below which the rate will not be reduced.

Trait Implementations

impl Clone for PlateauLR

fn clone(&self) -> PlateauLR

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for PlateauLR

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

Formats the value using the given formatter.

impl LRScheduler for PlateauLR

fn learning_rate(&mut self, _step: u64, current_loss: f64) -> f64

Return the learning rate for the given step and current_loss.

fn reset(&mut self)

Reset the scheduler to its initial state.