Struct PqCode 

pub struct PqCode { /* private fields */ }

A product-quantized (PQ) code: one u8 centroid index per subvector.

Produced by Quantizer::quantize on a trained ProductQuantizer. The byte at position m is the index (in 0..n_centroids, where n_centroids <= 256) of the centroid in subvector codebook m that best approximates the m-th subvector of the encoded vector. Decode it with Quantizer::dequantize (lossy) or compare it against a query through Quantizer::distance.

Examples

use iqdb_quantize::{ProductQuantizer, Quantizer};

let mut pq = ProductQuantizer::with_config(2, 4, 42);
let training: Vec<Vec<f32>> = (0..8)
    .map(|i| vec![i as f32, (i * 2) as f32, (i * 3) as f32, (i * 4) as f32])
    .collect();
let refs: Vec<&[f32]> = training.iter().map(Vec::as_slice).collect();
pq.train(&refs).expect("training succeeds");

let code = pq.quantize(&[1.0_f32, 2.0, 3.0, 4.0]).expect("quantize");
assert_eq!(code.n_subvectors(), 2);
assert_eq!(code.dim(), 4);
assert_eq!(code.as_bytes().len(), 2);

Implementations

impl PqCode

pub fn dim(&self) -> usize

Returns the original vector dimension this code was produced from.

Examples

use iqdb_quantize::{ProductQuantizer, Quantizer};

let mut pq = ProductQuantizer::with_config(2, 4, 7);
let training: Vec<Vec<f32>> = (0..8)
    .map(|i| vec![i as f32, (i + 1) as f32, (i + 2) as f32, (i + 3) as f32])
    .collect();
let refs: Vec<&[f32]> = training.iter().map(Vec::as_slice).collect();
pq.train(&refs).expect("training succeeds");
let code = pq.quantize(&[1.0_f32, 2.0, 3.0, 4.0]).expect("quantize");
assert_eq!(code.dim(), 4);

pub fn n_subvectors(&self) -> usize

Returns the number of subvectors M this code was produced under.

Equal to self.as_bytes().len() and to the ProductQuantizer::n_subvectors the code was produced with.

Examples

use iqdb_quantize::{ProductQuantizer, Quantizer};

let mut pq = ProductQuantizer::with_config(2, 4, 7);
let training: Vec<Vec<f32>> = (0..8)
    .map(|i| vec![i as f32, (i + 1) as f32, (i + 2) as f32, (i + 3) as f32])
    .collect();
let refs: Vec<&[f32]> = training.iter().map(Vec::as_slice).collect();
pq.train(&refs).expect("training succeeds");
let code = pq.quantize(&[1.0_f32, 2.0, 3.0, 4.0]).expect("quantize");
assert_eq!(code.n_subvectors(), 2);

pub fn len(&self) -> usize

Returns the number of bytes in the code (equal to PqCode::n_subvectors).

Examples

use iqdb_quantize::{ProductQuantizer, Quantizer};

let mut pq = ProductQuantizer::with_config(2, 4, 7);
let training: Vec<Vec<f32>> = (0..8)
    .map(|i| vec![i as f32, (i + 1) as f32, (i + 2) as f32, (i + 3) as f32])
    .collect();
let refs: Vec<&[f32]> = training.iter().map(Vec::as_slice).collect();
pq.train(&refs).expect("training succeeds");
let code = pq.quantize(&[1.0_f32, 2.0, 3.0, 4.0]).expect("quantize");
assert_eq!(code.len(), 2);

pub fn is_empty(&self) -> bool

Returns true if the code holds no centroid indices.

A PqCode produced by Quantizer::quantize on a trained ProductQuantizer is never empty (empty inputs and n_subvectors == 0 are rejected at the boundary); this method exists for API symmetry with PqCode::len.

Examples

use iqdb_quantize::{ProductQuantizer, Quantizer};

let mut pq = ProductQuantizer::with_config(2, 4, 7);
let training: Vec<Vec<f32>> = (0..8)
    .map(|i| vec![i as f32, (i + 1) as f32, (i + 2) as f32, (i + 3) as f32])
    .collect();
let refs: Vec<&[f32]> = training.iter().map(Vec::as_slice).collect();
pq.train(&refs).expect("training succeeds");
let code = pq.quantize(&[1.0_f32, 2.0, 3.0, 4.0]).expect("quantize");
assert!(!code.is_empty());

pub fn as_bytes(&self) -> &[u8]

Borrow the raw centroid-index bytes.

Examples

use iqdb_quantize::{ProductQuantizer, Quantizer};

let mut pq = ProductQuantizer::with_config(2, 4, 7);
let training: Vec<Vec<f32>> = (0..8)
    .map(|i| vec![i as f32, (i + 1) as f32, (i + 2) as f32, (i + 3) as f32])
    .collect();
let refs: Vec<&[f32]> = training.iter().map(Vec::as_slice).collect();
pq.train(&refs).expect("training succeeds");
let code = pq.quantize(&[1.0_f32, 2.0, 3.0, 4.0]).expect("quantize");
assert_eq!(code.as_bytes().len(), 2);

Trait Implementations

impl Clone for PqCode

fn clone(&self) -> PqCode

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for PqCode

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

Formats the value using the given formatter.

impl Eq for PqCode

impl PartialEq for PqCode

fn eq(&self, other: &PqCode) -> 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 StructuralPartialEq for PqCode