Struct LinUcbFast 

pub struct LinUcbFast { /* private fields */ }

Available on crate feature bandit only.

Preview high-performance LinUCB implementation.

LinUcbFast maintains A^-1 directly with the Sherman-Morrison rank-one update. Selection and update are O(arm_count * d^2) and O(d^2) respectively. Its serde state is Preview and is not part of the frozen LinUcb state schema.

Implementations

impl LinUcbFast

pub fn new(config: LinUcbConfig) -> Result<Self, RillError>

Create an empty fast LinUCB from the same configuration as LinUcb.

pub fn from_linucb(source: &LinUcb) -> Result<Self, RillError>

Convert a stable LinUCB state into the Preview fast representation.

pub fn inverse_matrix(&self, arm: usize) -> Result<&[Vec<f64>], RillError>

Borrow one cached inverse matrix.

pub const fn state_f64_count(&self) -> usize

Number of stored f64 values, excluding allocator metadata.

pub fn score_arm( &self, arm: usize, context: &[f64], ) -> Result<LinUcbArmScore, RillError>

Explain one arm score in O(d^2).

pub fn score_all( &self, context: &[f64], ) -> Result<Vec<LinUcbArmScore>, RillError>

Explain all arm scores in O(arm_count * d^2).

pub fn select_deterministic(&self, context: &[f64]) -> Result<usize, RillError>

Deterministic lowest-index tie-break for replay and audit.

pub fn validate(&self) -> Result<(), RillError>

Validate dimensions, finite values, symmetry and positive definiteness.

Trait Implementations

impl Clone for LinUcbFast

fn clone(&self) -> LinUcbFast

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl ContextualBandit for LinUcbFast

fn arm_count(&self) -> usize

The number of arms (actions) available.

fn feature_count(&self) -> usize

The number of features in the context vector.

fn samples_seen(&self) -> u64

How many total samples the bandit has observed.

fn select( &self, context: &[f64], rng: &mut impl Rng, ) -> Result<usize, RillError>

Select an arm given the context vector, using the provided RNG.

fn update( &mut self, arm: usize, context: &[f64], reward: f64, ) -> Result<(), RillError>

Update the bandit with the observed reward for a previously selected arm.

fn reset(&mut self)

Reset the bandit to its initial (no-data) state.

impl Debug for LinUcbFast

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

Formats the value using the given formatter.

impl ValidateState for LinUcbFast

fn validate_state(&self) -> Result<(), RillError>

Validate the in-memory state of this type.