Struct HyperLogLogPlus 

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

An implementation of the the HyperLogLog++ data structure.

For small cardinalities, a “sparse” representation is used. The sparse representation is more accurate and uses less memory, but has slower insert speed. The error and memory usage of the sparse representation scales roughly linearly with the number of items inserted. When the memory of the sparse representation equals the memory of the dense representation, it switches to dense automatically. This happens inside the insert/insert_hash call (which is why it needs &mut self). The error of the sparse representation never exceeds that of the dense.

Implementations

impl HyperLogLogPlus

pub fn new(precision: u8) -> Self

Returns a new Self using the default hasher with a random seed. Self is initialized to use the compact and dynamically sized sparse representation, but later switches to the dense representation when it uses equal memory (1 << precision registers (1 byte each)).

pub fn seeded(precision: u8, seed: u128) -> Self

Returns a new Self using the default hasher seeded with seed. Self is initialized to use the compact and dynamically sized sparse representation, but later switches to the dense representation when it uses equal memory (1 << precision registers, 1 byte each).

impl<S: BuildHasher> HyperLogLogPlus<S>

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

Returns a new Self using the provided hasher. Self is initialized to use the compact and dynamically sized sparse representation, but later switches to the dense representation when it uses equal memory (1 << precision registers, 1 byte each).

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

Inserts the hash of an item into the HyperLogLogPlus. self switches to dense mode if sparse mode exceeds memory usage of dense mode.

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

Inserts the item into the HyperLogLogPlus. self switches to dense mode if sparse mode exceeds memory usage of dense mode.

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 count(&mut self) -> usize

Returns the approximate number of elements in self.

pub fn raw_count(&mut self) -> f64

Returns the approximate number of elements in self.

pub fn is_sparse(&self) -> bool

Returns true if the current internal representation is sparse, false if using classic dense (HyperLogLog) representation.

pub fn precision(&self) -> u8

Returns the precision of 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 precision (Self::precision).

This does not verify that the HLLs use equal hashers or seeds. If they are different then self will be “corrupted”.

Trait Implementations

impl<S: Clone> Clone for HyperLogLogPlus<S>

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

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<S: Debug> Debug for HyperLogLogPlus<S>

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

Formats the value using the given formatter.

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