ngt-rs  

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

Building NGT requires CMake. By default ngt-rs will be built dynamically, which means that you'll need to make the build artifact libngt.so available to your final binary. You'll also need to have OpenMP installed on the system where it will run. If you want to build ngt-rs statically, then use the static Cargo feature, note that in this case OpenMP will be disabled when building NGT.

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()?;