Struct PositiveOnlyDDSketch 

pub struct PositiveOnlyDDSketch<M: IndexMapping = LogarithmicMapping, S: Store = CollapsingLowestDenseStore> { /* private fields */ }

A DDSketch optimized for positive-only values (e.g., latencies, durations).

This is a memory-optimized variant of DDSketch that eliminates the negative value store, saving 48 bytes per sketch instance. Use this when you know all values will be non-negative, such as when tracking latencies or other timing metrics.

Negative values are treated as zero (mapped to zero_count).

Example

use ddsketch::canonical::PositiveOnlyDDSketch;
use ddsketch::canonical::mapping::FixedLogarithmicMapping;
use ddsketch::canonical::store::CollapsingLowestDenseStore;

let mut sketch: PositiveOnlyDDSketch<FixedLogarithmicMapping, CollapsingLowestDenseStore> =
    PositiveOnlyDDSketch::default();
sketch.add(1.0);
sketch.add(2.0);
sketch.add(3.0);

let median = sketch.quantile(0.5).unwrap();

Implementations

impl<M: IndexMapping, S: Store> PositiveOnlyDDSketch<M, S>

pub fn new(mapping: M, positive_store: S) -> Self

Creates a new PositiveOnlyDDSketch with the given mapping and store.

pub fn add(&mut self, value: f64)

Adds a single value to the sketch.

Negative values are treated as zero.

pub fn add_n(&mut self, value: f64, n: u64)

Adds a value to the sketch with the given count.

Negative values are treated as zero.

pub fn quantile(&self, q: f64) -> Option<f64>

Returns the approximate value at the given quantile.

The quantile must be in the range of [0, 1].

Returns None if the sketch is empty, or if the quantile is out of bounds.

pub fn merge(&mut self, other: &Self)

where M: PartialEq,

Merges another sketch into this one.

The other sketch must use the same mapping type.

pub fn is_empty(&self) -> bool

Returns true if the sketch is empty.

pub fn count(&self) -> u64

Returns the total number of values added to the sketch.

pub fn clear(&mut self)

Clears the sketch, removing all values.

pub fn mapping(&self) -> &M

Returns a reference to the index mapping.

pub fn positive_store(&self) -> &S

Returns a reference to the positive value store.

pub fn zero_count(&self) -> u64

Returns the count of values mapped to zero.

pub fn relative_accuracy(&self) -> f64

Returns the relative accuracy of this sketch.

pub fn from_proto( proto: &ProtoDDSketch, mapping: M, ) -> Result<Self, ProtoConversionError>

where S: Default,

Creates a PositiveOnlyDDSketch from a protobuf DDSketch message.

This validates that the protobuf’s index mapping is compatible with the mapping type M, then populates the store with the positive bin data. Any negative values in the protobuf are ignored.

Errors

Returns an error if:

• The protobuf is missing a mapping
• The mapping parameters don’t match the provided mapping
• Any bin counts are negative or non-integer
• The zero count is negative or non-integer

pub fn to_proto(&self) -> ProtoDDSketch

Converts this PositiveOnlyDDSketch to a protobuf DDSketch message.

The resulting protobuf will have no negativeValues field set.

Trait Implementations

impl<M: Clone + IndexMapping, S: Clone + Store> Clone for PositiveOnlyDDSketch<M, S>

fn clone(&self) -> PositiveOnlyDDSketch<M, S>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<M: Debug + IndexMapping, S: Debug + Store> Debug for PositiveOnlyDDSketch<M, S>

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

Formats the value using the given formatter.

impl<M: IndexMapping + Default, S: Store + Default> Default for PositiveOnlyDDSketch<M, S>

fn default() -> Self

Returns the “default value” for a type.

impl<M: IndexMapping + PartialEq, S: Store + PartialEq> PartialEq for PositiveOnlyDDSketch<M, S>

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<M: IndexMapping + PartialEq, S: Store + PartialEq> Eq for PositiveOnlyDDSketch<M, S>