Struct HyperLogLog 

pub struct HyperLogLog<S = DefaultHasher> { /* private fields */ }

HyperLogLog is a data structure for the “count-distinct problem”, approximating the number of distinct elements in a multiset.

Example

use hyperloglockless::HyperLogLog;

let mut hll = HyperLogLog::new(16);
hll.insert("42");
hll.insert("🦀");

let count = hll.count();

Implementations

impl<S: BuildHasher> HyperLogLog<S>

pub fn with_hasher(precision: u8, hasher: S) -> Self

Returns a new HyperLogLog with 1 << precision registers (1 byte each) using the provided hasher.

impl HyperLogLog

pub fn new(precision: u8) -> HyperLogLog<DefaultHasher>

Returns a new Self with 1 << precision registers (1 byte each) using the default hasher with a random seed.

pub fn seeded(precision: u8, seed: u128) -> HyperLogLog<DefaultHasher>

Returns a new Self with 1 << precision registers (1 byte each) using the default hasher seeded with seed.

impl<S: BuildHasher> HyperLogLog<S>

pub fn len(&self) -> usize

Returns the number registers in self.

pub fn count(&self) -> usize

Returns the approximate number of elements in self.

impl<S: BuildHasher> HyperLogLog<S>

pub fn iter(&self) -> impl Iterator<Item = u8> + '_

Returns an iterator over the value of each register.

pub fn insert<T: Hash + ?Sized>(&mut self, value: &T)

Inserts the item into the HyperLogLog.

pub fn insert_hash(&mut self, hash: u64)

Inserts the hash of an item into the HyperLogLog.

pub fn insert_all<T: Hash, I: IntoIterator<Item = T>>(&mut self, iter: I)

Inserts all the items in iter into the self.

pub fn union(&mut self, other: &Self) -> Result<(), Error>

Merges another HyperLogLog into self, updating the count. Returns Err(Error::IncompatibleLength) if the two HyperLogLogs have different length (Self::len).

This does not verify that the HLLs use the same hasher or seed. If they are different then self will be “corrupted”.

pub fn raw_count(&self) -> f64

Returns the approximate number of elements in self.

pub fn parts<'a>(&'a self) -> (&'a [u8], &'a S, usize, f64)

Low level method to expose de/serializable parts of self.

pub fn from_parts( registers: Box<[u8]>, hasher: S, zeros: usize, sum: f64, ) -> Self

Low level method to construct Self de/serializable parts.

Example

use hyperloglockless::HyperLogLog;

let mut before = HyperLogLog::seeded(16, 42);
before.extend(1000..=2000);
let (x, y, z, w) = before.parts();
let after = HyperLogLog::from_parts(x.into(), y.clone(), z, w);
assert_eq!(before, after);

Trait Implementations

impl<S: Clone> Clone for HyperLogLog<S>

fn clone(&self) -> HyperLogLog<S>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<S: Debug> Debug for HyperLogLog<S>

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

Formats the value using the given formatter.

impl<T: Hash, S: BuildHasher> Extend<T> for HyperLogLog<S>

fn extend<I: IntoIterator<Item = T>>(&mut self, iter: I)

Extends a collection with the contents of an iterator.

fn extend_one(&mut self, item: A)

🔬This is a nightly-only experimental API. (extend_one)

Extends a collection with exactly one element.

fn extend_reserve(&mut self, additional: usize)

🔬This is a nightly-only experimental API. (extend_one)

Reserves capacity in a collection for the given number of additional elements.

impl<S: BuildHasher> PartialEq for HyperLogLog<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<S: BuildHasher> Eq for HyperLogLog<S>