Struct HyperLogLog 

pub struct HyperLogLog {
    pub registers: Vec<u8>,
    pub m: usize,
    pub alpha: f64,
    /* private fields */
}

A single HyperLogLog sketch for estimating cardinality.

Parameters

• precision (b) — controls the number of registers m = 2^b. Precision must be in the range [4, 16]. Higher precision → less error but more memory. Typical error rate: ~1.04 / sqrt(m).

Fields

registers: Vec<u8>

m = 2^precision registers, each storing the maximum leading-zero count.

m: usize

Number of registers (m = 2^precision).

alpha: f64

Bias-correction constant α_m.

Implementations

impl HyperLogLog

pub fn new(precision: u8) -> Self

Create a new HyperLogLog sketch.

Panics

Panics if precision < 4 or precision > 16.

pub fn add(&mut self, item: &str)

Add an item to the sketch.

pub fn count(&self) -> u64

Estimate the number of distinct items added.

pub fn merge(&mut self, other: &HyperLogLog) -> Result<(), CounterError>

Merge another HLL sketch into this one by taking the per-register max.

Both sketches must have the same precision.

pub fn clear(&mut self)

Reset all registers to zero.

pub fn register_count(&self) -> usize

Return the number of registers in this sketch.

Trait Implementations

impl Clone for HyperLogLog

fn clone(&self) -> HyperLogLog

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for HyperLogLog

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

Formats the value using the given formatter.