Struct CompressedHistogram

pub struct CompressedHistogram { /* private fields */ }

Though not fixed, CompressedHistogram encodes histograms using less space than a StandardHistogram. All of the frequencies for each label are approximated by a next greatest exponent. CompressedHistogram uses a library HashMap to store the label-frequency pairs, so it is unbounded in terms of space. It is associated with CompressedParams

There are 2 parameters:

• b -> This floating point number is the base of the approximating exponent.
• max_exp -> This is the number of distinct values that can potentially be stored.

A CompressedHistogram must be derived from a StandardHistogram using the to_compressed function.

Trait Implementations

impl Histogram<CompressedParams, usize, usize> for CompressedHistogram

fn total(&self) -> usize

returns whichever is greater, the compressed or decompressed size

fn labels( &self, _params: &CompressedParams, ) -> Option<Box<dyn Iterator<Item = usize>>>

If possible, creates and returns an iterator for the labels for which the histogram has frequencies stored.

fn frequency(&self, label: usize, params: &CompressedParams) -> Option<usize>

If possible, returns the frequency of a particular label. The behavior need only be defined if the label is in the set of values returned from labels.