Struct FacContextTree 

pub struct FacContextTree { /* private fields */ }

Factorized Action-Conditional Context Tree Weighting.

FAC-CTW uses k separate context trees, one for each bit of the percept space. Tree i (0-indexed) has depth base_depth + i, ensuring each percept bit is dependent on the same portion of history while incorporating type information.

Optimization: All trees share a single history vector. Each tree tracks only its effective history length, avoiding k-way duplication of history data.

Reference: Veness et al. (2011), Section 5, Equation 33-34.

Implementations

impl FacContextTree

pub fn new(base_depth: usize, num_percept_bits: usize) -> Self

Creates a new FAC-CTW with base_depth D and num_percept_bits k.

Tree i will have depth D + i to ensure proper context overlap.

pub fn num_bits(&self) -> usize

Returns the number of percept bits (k).

pub fn base_depth(&self) -> usize

Returns the base context depth (D).

pub fn update(&mut self, sym: bool, bit_index: usize)

Updates tree bit_index with symbol sym and updates subsequent trees’ effective lengths.

Call this in sequence for bits 0..k of each percept.

pub fn predict(&mut self, sym: bool, bit_index: usize) -> f64

Predicts the probability of sym at bit_index.

pub fn revert(&mut self, bit_index: usize)

Reverts the update at bit_index.

pub fn update_history(&mut self, symbols: &[bool])

Updates all trees’ effective history lengths with action symbols (no KT update).

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

Reverts history from all trees.

pub fn get_log_block_probability(&self) -> f64

Returns the combined log block probability (sum of all trees).

pub fn clear(&mut self)

Clears all trees and shared history.

pub fn memory_usage(&self) -> usize

Returns approximate memory usage in bytes (including shared history).

Trait Implementations

impl Clone for FacContextTree

fn clone(&self) -> FacContextTree

Returns a duplicate of the value.

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

Performs copy-assignment from source.