Struct SlidingWindowUcb1 

pub struct SlidingWindowUcb1 { /* private fields */ }

A sliding-window UCB1 bandit for non-stationary rewards.

Plain Ucb1 assumes the reward distribution never changes, so its confidence bound shrinks as 1/√n forever and old samples pin the estimate — which is wrong for a game session, where the best layout in a quiet scene is not the best in a crowded one. This variant scores each arm over only its most recent window rewards (a per-arm ring buffer), so it keeps adapting when the workload shifts. It is still fully deterministic (no RNG), matching the reproducibility the adaptive layer requires.

(Garivier & Moulines, On Upper-Confidence Bound Policies for Non-Stationary Bandit Problems, 2011 — the SW-UCB construction.)

Implementations

impl SlidingWindowUcb1

pub fn new(num_arms: usize, window: usize) -> Self

Creates a bandit with num_arms arms (min 1), each scored over its last window rewards (min 1), using the default exploration constant √2.

pub fn with_exploration( num_arms: usize, window: usize, exploration: f64, ) -> Self

Creates a bandit with an explicit exploration constant c.

pub fn arm_count(&self) -> usize

The number of arms.

pub fn samples(&self, arm: usize) -> usize

How many rewards are currently retained for arm (capped at the window).

pub fn select(&self) -> usize

Selects the next arm: any arm with an empty window first (forced exploration), otherwise the highest windowed UCB score.

pub fn record(&mut self, arm: usize, reward: f64)

Records a reward for arm into its window (evicting the oldest once full). Out-of-range arms and non-finite rewards are ignored.

pub fn best_arm(&self) -> Option<usize>

The best arm by current windowed mean (pure exploitation), or None until at least one arm has a reward.

pub fn mean_reward(&self, arm: usize) -> Option<f64>

The current windowed mean reward for arm, or None if its window is empty.

Trait Implementations

impl Clone for SlidingWindowUcb1

fn clone(&self) -> SlidingWindowUcb1

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for SlidingWindowUcb1

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

Formats the value using the given formatter.