Huffman

Implementation of Huffman Coding algorithm for lossless text compression.

I wrote some stuff about this project here.

Here are a few results:

Text File	Original Size	Compressed Size	% Smaller
big.txt	6.2M	3.5M	44%
beowulf.txt	294K	163K	45%
wai-pageauth.txt	82K	47K	43%
amendments.txt	44K	25K	43%
utf8-demo.txt	14K	8.5K	39%
russian-lorem.txt	4.5K	1.4K	68%
english-lorem.txt	1.2K	738B	39%
small.txt	28B	38B	36% increase

It works best on large text files. Small text files actually get larger after compression using this technique because there is overhead.

Usage

Interactive Elixir console

iex(1)> {encoded_bits, mapping} = Huffman.compress("hello world")
{"h'iO",
 %{2 => %{<<0::size(2)>> => "l"},
   3 => %{<<2::size(3)>> => "e", <<3::size(3)>> => "h", <<4::size(3)>> => "o",
     <<5::size(3)>> => "r", <<6::size(3)>> => "w"},
   4 => %{<<14::size(4)>> => " ", <<15::size(4)>> => "d"}}}

iex(2)> Huffman.decompress(encoded_bits, mapping)
"hello world"

Read/Write to file from interactive Elixir console

iex(1)> Huffman.Files.compress("./sample_text/amendments.txt", "./out.txt.huff")
"Data written to -> ./out.txt"

iex(2)> Huffman.Files.decompress("./out.txt.huff", "./out.txt")
"File decompression complete ./out.txt"

Command line usage

First, build the executable:

$ mix escript.build
Generated escript huffman with MIX_ENV=dev

$ ./huffman
Command line tool for Huffman Coding Text compression

OPTIONS
=================================
--compress path/to/text_file.txt --output-path path/to/output_file.huff

--decompress path/to/compressed_file.huff --output-path path/to/output_file.txt

Contributing

This code could of course be improved, so feel free to contribute.