huffman-compress

Huffman compression given a probability distribution over arbitrary symbols.

Examples

use std::iter::FromIterator;
use std::collections::HashMap;
use bit_vec::BitVec;
use huffman_compress::{CodeBuilder, Book, Tree};

let mut weights = HashMap::new();
weights.insert("CG", 293);
weights.insert("AG", 34);
weights.insert("AT", 4);
weights.insert("CT", 4);
weights.insert("TG", 1);

// Construct a Huffman code based on the weights (e.g. counts or relative
// frequencies).
let (book, tree) = CodeBuilder::from_iter(weights).finish();

// More frequent symbols will be encoded with fewer bits.
assert!(book.get("CG").map_or(0, |cg| cg.len()) <
        book.get("AG").map_or(0, |ag| ag.len()));

// Encode some symbols using the book.
let mut buffer = BitVec::new();
let example = vec!["AT", "CG", "AT", "TG", "AG", "CT", "CT", "AG", "CG"];
for symbol in &example {
    book.encode(&mut buffer, symbol);
}

// Decode the symbols using the tree.
let decoded: Vec<&str> = tree.decoder(&buffer).collect();
assert_eq!(decoded, example);

Documentation

Read the documentation

Changelog

• 0.6.1
  • Fix deprecation warning and remove #[deny(warnings)] (a future compatibility hazard in libraries).
• 0.6.0
  • Update to bit-vec 0.6.
• 0.5.0
  • Update to bit-vec 0.5.
• 0.4.0
  • Renamed Tree::decoder() to Tree::unbounded_decoder() to avoid surprises. A new Tree::decoder() takes the maximum number of symbols to decode.
  • No longer reexporting Saturating from num-traits.
• 0.3.2
  • Preallocate arena space for Huffman tree.
• 0.3.1
  • Update num-traits to 0.2 (semver compatible).
• 0.3.0
  • Introduce CodeBuilder.
  • Changes tie breaking order.
• 0.2.0
  • Allow initialization from iterators without creating a HashMap. Thanks @mernen.
  • Require K: Ord instead of K: Hash + Eq for symbols and switch Book internals from HashMap to BTreeMap.
  • Specify stability guarantees.
• 0.1.1
  • Expose more methods on Book.
• 0.1.0
  • Initial release.

License

huffman-compress is dual licensed under the Apache 2.0 and MIT license, at your option.