Enum Metric 

pub enum Metric {
    L2,
    InnerProduct,
    Cosine,
}

Distance metric used to compare query and database vectors.

Ranking convention

Throughout Slate-ANN, search ranks candidates by an ascending score: smaller means closer. Each metric defines how a raw similarity maps onto that convention, so a single “smaller-is-better” priority queue works for every metric:

Metric	Score computed by kernels	Smaller = closer?
L2	squared Euclidean distance	yes (natural)
InnerProduct	negated inner product (-<a,b>)	yes (negated)
Cosine	1 - cosine_similarity	yes

L2 uses the squared distance to avoid a per-comparison sqrt; the ordering is identical to true Euclidean distance and the square root can be applied once to final results if an actual distance is needed.

Variants

L2

Squared Euclidean (L2) distance.

InnerProduct

Inner (dot) product similarity, scored as its negation.

Cosine

Cosine distance (1 - cosine_similarity).

Implementations

impl Metric

pub const fn requires_normalized_input(self) -> bool

Whether this metric requires inputs to be L2-normalized for correct results.

Cosine is implemented as inner product over unit-normalized vectors, so the engine normalizes both database and query vectors when this is true.

pub const fn as_str(self) -> &'static str

Lower-case identifier used in the on-disk metadata file.

Trait Implementations

impl Clone for Metric

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for Metric

impl Debug for Metric

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

Formats the value using the given formatter.

impl Default for Metric

fn default() -> Self

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for Metric

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Eq for Metric

impl Hash for Metric

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for Metric

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

Equality operator ==.

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

Inequality operator !=.

impl Serialize for Metric

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for Metric