mreid

# LZ77 Encoding
#
# Simple implementation of Lempel-Ziv 77 (a.k.a. "Sliding Window") coding
# as described in Section 13.4 of Cover & Thomas' "Information Theory".
#
# USAGE: python encode.py INPUT_STREAM
#
# EXAMPLE (from lectures):
#    $ python encode.py abbababbababbab
#    (0,a)

mreid

# Hamming (7,4) Coding
#
# Reads binary stream from standard input and outputs Hamming (7,4) encoded
# version to standard output.
#
# USAGE: python h74-encode.py
#
# EXAMPLE:
#      $ echo "0001" | python h74-encode.py
#      1000101

mreid

# Example Huffman coding implementation
# Distributions are represented as dictionaries of { 'symbol': probability }
# Codes are dictionaries too: { 'symbol': 'codeword' }

def huffman(p):
    '''Return a Huffman code for an ensemble with distribution p.'''
    assert(sum(p.values()) == 1.0) # Ensure probabilities sum to 1

    # Base case of only two symbols, assign 0 or 1 arbitrarily
    if(len(p) == 2):