Struct TransitionCounter 

pub struct TransitionCounter<S: Eq + Hash + Clone> { /* private fields */ }

In-memory frequency matrix for (from, to) transition counting.

Generic over state type S (typically String for screen IDs).

Implementations

impl<S: Eq + Hash + Clone> TransitionCounter<S>

pub fn new() -> Self

Create a new empty counter with default smoothing.

pub fn with_config(smoothing_alpha: f64, prune_threshold: f64) -> Self

Create a counter with custom smoothing alpha and prune threshold.

pub fn record(&mut self, from: S, to: S)

Record a single transition from from to to (increments by 1.0).

pub fn record_with_count(&mut self, from: S, to: S, count: f64)

Record a transition with an explicit count (used by persistence layer).

pub fn count(&self, from: &S, to: &S) -> f64

Get the raw count for a specific transition.

pub fn total_from(&self, from: &S) -> f64

Get the total transitions originating from from.

pub fn total(&self) -> f64

Get the total number of recorded transitions.

pub fn probability(&self, from: &S, to: &S) -> f64

Compute the probability of transitioning from from to to.

Uses Laplace (additive) smoothing: P(to|from) = (count(from,to) + alpha) / (total_from(from) + alpha * N) where N is the number of known target states from from.

Returns a uniform estimate if from has no recorded transitions.

pub fn all_targets_ranked(&self, from: &S) -> Vec<(S, f64)>

Return all known targets from from, ranked by probability (descending).

pub fn merge(&mut self, other: &TransitionCounter<S>)

Merge another counter into this one (additive).

pub fn decay(&mut self, factor: f64)

Apply temporal decay: multiply all counts by factor.

factor should be in (0.0, 1.0). Entries that fall below the prune threshold are removed to prevent unbounded map growth.

pub fn state_ids(&self) -> HashSet<S>

Return the set of all known state IDs (both sources and targets).

Trait Implementations

impl<S: Clone + Eq + Hash + Clone> Clone for TransitionCounter<S>

fn clone(&self) -> TransitionCounter<S>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<S: Debug + Eq + Hash + Clone> Debug for TransitionCounter<S>

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

Formats the value using the given formatter.

impl<S: Eq + Hash + Clone> Default for TransitionCounter<S>

fn default() -> Self

Returns the “default value” for a type.