Struct F2Sketch 

pub struct F2Sketch { /* private fields */ }

Estimates the second frequency moment F2 = sum_k f_k^2 of a stream of hashed keys, where f_k is the number of times key k was inserted.

This is a single row of a Count-Sketch (the “fast AMS” sketch): every hash adds +1 or -1 to one of 64 buckets, and the sum of squared buckets is an unbiased estimate of F2 with a relative standard error of ~18%.

Implementations

impl F2Sketch

pub fn new() -> Self

pub fn insert(&mut self, h: u64)

Add a new hash to the sketch.

pub fn num_inserts(&self) -> u64

pub fn estimate(&self) -> f64

Trait Implementations

impl Clone for F2Sketch

fn clone(&self) -> F2Sketch

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Default for F2Sketch

fn default() -> Self

Returns the “default value” for a type.