Crate ngt

Rust wrappers for NGT, which provides high-speed approximate nearest neighbor searches against a large volume of data.

Note that NGT will be built dynamically for your target and this requires cmake. Furthermore, NGT's shared memory and large dataset features are available through cargo features shared_mem and large_data respectively.

Usage

Defining the properties of a new index:

use ngt::{Properties, DistanceType, ObjectType};

// Defaut properties with vectors of dimension 3
let prop = Properties::dimension(3)?;

// Or customize values (here are the defaults)
let prop = Properties::dimension(3)?
    .creation_edge_size(10)?
    .search_edge_size(40)?
    .object_type(ObjectType::Float)?
    .distance_type(DistanceType::L2)?;

Creating/Opening an index and using it:

use ngt::{Index, Properties, EPSILON};

// Create a new index
let prop = Properties::dimension(3)?;
let index = Index::create("target/path/to/index/dir", prop)?;

// Open an existing index
let mut index = Index::open("target/path/to/index/dir")?;

// Insert two 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)?;

// Actually build the index (not yet persisted on disk)
// This is required in order to be able to search vectors
index.build(2)?;

// Perform a vector search (with 1 result)
let res = index.search(&vec![1.1, 2.1, 3.1], 1, EPSILON)?;
assert_eq!(res[0].id, id1);
assert_eq!(index.get_vec(id1)?, vec![1.0, 2.0, 3.0]);

// Remove a vector and check that it is not present anymore
index.remove(id1)?;
let res = index.get_vec(id1);
assert!(matches!(res, Result::Err(_)));

// Verify that now our search result is different
let res = index.search(&vec![1.1, 2.1, 3.1], 1, EPSILON)?;
assert_eq!(res[0].id, id2);
assert_eq!(index.get_vec(id2)?, vec![4.0, 5.0, 6.0]);

// Persist index on disk
index.persist()?;

Modules

optim

Structs

Error
Index
Properties
SearchResult

Enums

DistanceType
ObjectType

Constants

EPSILON

Type Definitions

VecId