Crate mih_rs[−][src]

Expand description

mih-rs

Rust implementation of multi-index hashing (MIH) for neighbor searches on binary codes in the Hamming space, described in the paper

Norouzi, Punjani, and Fleet, Fast exact search in Hamming space with multi-index hashing, IEEE TPAMI, 36(6):1107– 1119, 2014.

Features

Two types of neighbor searches: mih-rs provides the two search operations:
- Range search finds neighbor codes whose Hamming distances to a given code are within a radius.
- Top-K search finds the top-K codes that are closest to a given code.
Fast and memory-efficient implementation: The data structure is built on sparse hash tables, following the original implementation.
Parameter free: mih-rs automatically sets an optimal parameter of MIH depending on a given database (although you can also set this manually).
Serialization: mih-rs supports to serialize/deserialize the index.

Example

use mih_rs::Index;

// Database of codes
let codes: Vec<u64> = vec![
    0b1111111111111111111111011111111111111111111111111011101111111111, // #zeros = 3
    0b1111111111111111111111111111111101111111111011111111111111111111, // #zeros = 2
    0b1111111011011101111111111111111101111111111111111111111111111111, // #zeros = 4
    0b1111111111111101111111111111111111111000111111111110001111111110, // #zeros = 8
    0b1101111111111111111111111111111111111111111111111111111111111111, // #zeros = 1
    0b1111111111111111101111111011111111111111111101001110111111111111, // #zeros = 6
    0b1111111111111111111111111111111111101111111111111111011111111111, // #zeros = 2
    0b1110110101011011011111111111111101111111111111111000011111111111, // #zeros = 11
];

// Query code
let qcode: u64 = 0b1111111111111111111111111111111111111111111111111111111111111111; // #zeros = 0

// Construct the index
let index = Index::new(codes).unwrap();

// Find the ids of neighbor codes whose Hamming distances are within 2
let mut searcher = index.range_searcher();
let answers = searcher.run(qcode, 2);
assert_eq!(answers, vec![1, 4, 6]);

// Find the ids of the top-4 nearest neighbor codes
let mut searcher = index.topk_searcher();
let answers = searcher.run(qcode, 4);
assert_eq!(answers, vec![4, 1, 6, 0]);

// Serialization/Deserialization
let mut data = vec![];
index.serialize_into(&mut data).unwrap();
let other = Index::<u64>::deserialize_from(&data[..]).unwrap();
assert_eq!(index, other);

mih_rs::Index can be built from a vector of type mih_rs::CodeInt that is a primitive integer trait supporting a popcount operation. Currently, this library defines mih_rs::CodeInt for u8, u16, u32, and u64.