Available on crate feature
quantized only.Expand description
Quantized blob graph index (QBG Index)
Defining the properties of a new QBG index:
use ngt::qbg::{QbgConstructParams, QbgDistance};
// Defaut parameters with vectors of dimension 3
let params = QbgConstructParams::<f32>::dimension(3);
// Or customize values (here are the defaults)
let params = QbgConstructParams::<f32>::dimension(3)
.extended_dimension(16)? // next multiple of 16 after 3
.number_of_subvectors(1)
.number_of_blobs(0)
.distance_type(QbgDistance::L2);
Creating/Opening a QBG index and using it:
use ngt::qbg::{
ModeRead, ModeWrite, QbgBuildParams, QbgConstructParams, QbgDistance, QbgIndex, QbgQuery,
};
// Create a new index
let params = QbgConstructParams::dimension(3);
let mut index: QbgIndex<f32, ModeWrite> =
QbgIndex::create("target/path/to/qbg_index/dir", params)?;
// Insert vectors and get their id
let vec1 = vec![1.0, 2.0, 3.0];
let vec2 = vec![4.0, 5.0, 6.0];
let id1 = index.insert(vec1)?;
let id2 = index.insert(vec2)?;
// Add enough dummy vectors to build an index
for i in 0..64 {
index.insert(vec![100. + i as f32; 3])?;
}
// Build the index in RAM and persist it on disk
index.build(QbgBuildParams::default())?;
index.persist()?;
// Open an existing index
let index: QbgIndex<f32, ModeRead> = QbgIndex::open("target/path/to/qbg_index/dir")?;
// Perform a vector search (with 1 result)
let query = vec![1.1, 2.1, 3.1];
let res = index.search(QbgQuery::new(&query).size(1))?;
assert_eq!(res[0].id, id1);
assert_eq!(index.get_vec(id1)?, vec![1.0, 2.0, 3.0]);