Struct basichll::HLL
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[src]
pub struct HLL {
// some fields omitted
}The HLL struct stores the underlying registers
of the HyperLogLog, with m many registers.
The value for m is derived from the desired error
of the estimation. The error is considered to be
1.04 / sqrt(2 ^ bits). So, given a desired 1% error
rate, we result in around 12 bits per register,
producing an underlying M of 212 bits (i.e. 4kb).
Methods
impl HLL
fn one_hundred_twenty_eight() -> HLL
Convenience function to produce a HLL with one hundred and twenty eight registers.
fn new(error: f64) -> HLL
Create a new HLL with the desired standard error. Some examples might be:
bits size error 12 4096 0.0163 13 8192 0.0115 14 16384 0.0081
The error must be between 0.0 and 1.0. Beware using a stupidly small error size will grow beyond e.g. isize at less than 0.03 (if you need something that isn't an estimate probably don't use a hyperloglog).
fn insert<T: Hash>(&mut self, val: &T)
Add an element into the hyperloglog estimate. We require the type of value to be able to be hashed.
fn count(&self) -> f64
Return the estimated cardinality of the observed set of elements.
fn registers(&self) -> Vec<u8>
Access a copy of the underlying registers (this is mainly here just for debugging/testing... its unlikely you'll need this access typically).
fn clone(&self) -> HLL
Copies this instance into a new HLL. Doesn't do anything tricky (i.e. this will entirely re-allocate the underlying registers).
fn empty() -> HLL
A completely zeroed HLL. Not particularly useful
except as an identity element in Add.
Trait Implementations
impl Display for HLL
impl Debug for HLL
impl Eq for HLL
A HLL is considered equal to another HLL when its configuration and registers are exactly identical.
impl PartialEq for HLL
impl<'a> Add<&'a HLL> for &'a HLL
Adding together two HLLs produces a new HLL where the larger value of each register has been selected.