Enum MultiValueCombiner 

pub enum MultiValueCombiner {
    Sum,
    Max,
    Avg,
    LogSumExp {
        temperature: f32,
    },
    WeightedTopK {
        k: usize,
        decay: f32,
    },
}

Strategy for combining scores when a document has multiple values for the same field

Variants

Sum

Sum all scores (accumulates dot product contributions)

Max

Take the maximum score

Avg

Take the average score

LogSumExp

Softmax-weighted smooth maximum (default) score = Σ softmax(t * sᵢ) * sᵢ Higher temperature → closer to max; lower → closer to mean.

Deliberately NOT the raw (1/t)·log(Σ exp(t·sᵢ)): that form adds ln(n)/t per document, so chunk count outranked chunk quality — a 300-chunk compendium of mediocre matches beat every focused paper (score 0.55 + ln(300)/1.5 ≈ 4.3 vs 0.72 + ln(3)/1.5 ≈ 1.4). The softmax weighting is count-invariant (n identical scores combine to that score), bounded by the max, and still tracks a dominant score at any scale.

Fields

temperature: f32

Temperature parameter (default: 1.5)

WeightedTopK

Weighted Top-K: weight top scores with exponential decay score = Σ wᵢ * sorted_scores[i] where wᵢ = decay^i

Fields

k: usize

Number of top scores to consider (default: 5)

decay: f32

Decay factor per rank (default: 0.7)

Implementations

impl MultiValueCombiner

pub fn log_sum_exp() -> Self

Create LogSumExp combiner with default temperature (1.5)

pub fn log_sum_exp_with_temperature(temperature: f32) -> Self

Create LogSumExp combiner with custom temperature

pub fn weighted_top_k() -> Self

Create WeightedTopK combiner with defaults (k=5, decay=0.7)

pub fn weighted_top_k_with_params(k: usize, decay: f32) -> Self

Create WeightedTopK combiner with custom parameters

pub fn combine(&self, scores: &[(u32, f32)]) -> f32

Combine multiple scores into a single score

Trait Implementations

impl Clone for MultiValueCombiner

fn clone(&self) -> MultiValueCombiner

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for MultiValueCombiner

impl Debug for MultiValueCombiner

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

Formats the value using the given formatter.

impl Default for MultiValueCombiner

fn default() -> Self

Returns the “default value” for a type.

impl PartialEq for MultiValueCombiner

fn eq(&self, other: &MultiValueCombiner) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for MultiValueCombiner