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//! This library contains tools for <b>simulating</b> space efficient histograms.
//! For the purposes of this library, a histogram is a map from labels to
//! frequencies, both of which must be numerical.
//!
//! We provide is a standard histogram implementation ([`StandardHistogram`]) which
//! stores label-frequency pairs at face value using a HashMap.
//!
//! Furthermore, we provide three additional histogram implementations that use either
//! strictly less memory than [`StandardHistogram`] or use a fixed amount of memory. The
//! optimizations are done across two dimensions, the label storage (referred to as "compaction")
//! and the frequency storage (referred to as "compression").
//! Hence the name "C-Squared Histograms". The three implementations are as follows:
//! - [`CompressedHistogram`] - This implementation uses strictly less space than a [`StandardHistogram`]
//! by approximating the frequencies
//! - [`CompactHistogram`] - This implementation consumes a fixed amount of space depending on a few
//! precision parameters. It saves space by approximating labels.
//! - [`C2Histogram`] - This implementation also utilizes a fixed amount of space, usually much less
//! than a CompactHistogram. It approximates both labels and frequencies.
//!
//! Each of these implementations is parameterized such that the trade-off between precision and
//! memory performance is directly controlled by the user.
//!
//! To construct a [`StandardHistogram`], use the function [`create_standard_histogram`]. Then,
//! the other histograms can be derived from that standard histogram using the conversion functions
//! [`to_compact`], [`to_compressed`], or [`to_c2`].
//!
//!
//! [`CompactHistogram`]: c2/struct.CompactHistogram.html
//! [`StandardHistogram`]: standard/struct.StandardHistogram.html
//! [`create_standard_histogram`]: standard/fn.create_standard_histogram.html
//! [`to_compact`]: standard/struct.StandardHistogram.html#method.to_compact
//! [`to_compressed`]: standard/struct.StandardHistogram.html#method.to_compressed
//! [`to_c2`]: standard/struct.StandardHistogram.html#method.to_c2
//! [`C2Histogram`]: c2/struct.C2Histogram.html
//! [`CompressedHistogram`]: c2/struct.CompressedHistogram.html

/// General trait definitions and [`StandardHistogram`] implementation
///
/// [`StandardHistogram`]: struct.StandardHistogram.html
pub mod standard;

/// Space saving histogram implementations
pub mod c2;