Struct HyperLogLog 

pub(crate) struct HyperLogLog<T>
where
    T: Hash + ?Sized,
{
    registers: [u8; 16384],
    phantom: PhantomData<T>,
}

Fields

registers: [u8; 16384]

phantom: PhantomData<T>

Implementations

impl<T> HyperLogLog<T>

where T: Hash + ?Sized,

pub fn new() -> Self

Creates a new, empty HyperLogLog.

pub(crate) fn new_with_registers(registers: [u8; 16384]) -> Self

Creates a HyperLogLog from already populated registers note that this method should not be invoked in untrusted environment because the internal structure of registers are not examined.

fn hash_value(&self, obj: &T) -> u64

choice of hash function: ahash is already an dependency and it fits the requirements of being a 64bit hash with reasonable performance.

pub fn add(&mut self, obj: &T)

Adds an element to the HyperLogLog.

fn get_histogram(&self) -> [u32; 52]

Get the register histogram (each value in register index into the histogram; u32 is enough because we only have 2**14=16384 registers

pub fn merge(&mut self, other: &HyperLogLog<T>)

Merge the other HyperLogLog into this one

pub fn count(&self) -> usize

Guess the number of unique elements seen by the HyperLogLog.

Trait Implementations

impl<T> AsRef<[u8]> for HyperLogLog<T>

where T: Hash + ?Sized,

fn as_ref(&self) -> &[u8]

Converts this type into a shared reference of the (usually inferred) input type.

impl<T> Clone for HyperLogLog<T>

where T: Hash + ?Sized + Clone,

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

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<T> Debug for HyperLogLog<T>

where T: Hash + ?Sized + Debug,

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

Formats the value using the given formatter.

impl<T> Default for HyperLogLog<T>

where T: Hash + ?Sized,

fn default() -> Self

Returns the “default value” for a type.

impl<'a, T> Extend<&'a T> for HyperLogLog<T>

where T: 'a + Hash + ?Sized,

fn extend<S: IntoIterator<Item = &'a T>>(&mut self, iter: S)

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<T> Extend<T> for HyperLogLog<T>

where T: Hash,

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

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<T: Hash> From<&HyperLogLog<T>> for ScalarValue

fn from(v: &HyperLogLog<T>) -> ScalarValue

Converts to this type from the input type.

impl<T: Hash> TryFrom<&[u8]> for HyperLogLog<T>

type Error = DataFusionError

The type returned in the event of a conversion error.

fn try_from(v: &[u8]) -> Result<HyperLogLog<T>>

Performs the conversion.

impl<T: Hash> TryFrom<&ScalarValue> for HyperLogLog<T>

type Error = DataFusionError

The type returned in the event of a conversion error.

fn try_from(v: &ScalarValue) -> Result<HyperLogLog<T>>

Performs the conversion.