thinset 0.3.0

A data structure for sparse sets of unsigned integers that sacrifices space for speed.
Documentation

crates.io Documentation Rust CI rustc 1.0+ Dependency Status Download Status

Usage

Add this to your Cargo.toml:

[dependencies]
thinset = "0.1"

Description

An implementation of a set and a map using a pair of sparse and dense arrays as backing stores.

This type of set is useful when you need to efficiently track set membership for integers from a large universe, but the values are relatively spread apart.

The sparse set supports constant-time insertion, removal, lookups as expected. In addition:

  • Compared to the standard library's HashSet, clearing the set is constant-time instead of linear time.
  • Compared to bitmap-based sets like the bit-set crate, iteration over the set is proportional to the cardinality of the set (how many elements you have) instead of proportional to the maximum size of the set.

The main downside is that the set requires more memory than other set implementations.

The map behaves identically to the set with the exception that it tracks data alongside the values that are stored in the set. Under the hood, SparseSet is a SparseMap of keys to ().

The implementation is based on the paper "An efficient representation for sparse sets" (1993) by Briggs and Torczon.

Examples

use thinset::SparseSet;

let mut s: SparseSet<usize> = SparseSet::new();
s.insert(0);
s.insert(3);
s.insert(7);

s.remove(7);

if !s.contains(7) {
    println!("There is no 7");
}

// Print 0, 1, 3 in some order
for x in s.iter() {
    println!("{}", x);
}

use thinset::{Pair, SparseMap};

let mut m: SparseMap<u32, u32> = SparseMap::new();

m.insert(13, 2);
m.insert(8, 16);

assert_eq!(m.get(13), Some(&2));
assert_eq!(m.get(6), None);

for Pair {key, value} in m.iter() {
    println!("{key}:{value}");
}

License

Dual-licensed for compatibility with the Rust project.

Licensed under the Apache License Version 2.0: http://www.apache.org/licenses/LICENSE-2.0, or the MIT license: http://opensource.org/licenses/MIT, at your option.