Lampel-Ziv 78 (LZ78) implementation in Python

LZ78.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# Lampel-Ziv 78 (LZ78)
# Théorie de l'information et du codage
# Etudiant: Boubakr NOUR <[email protected]>
# Universite Djilali Liabes (UDL) de Sidi Bel Abbes


def compress(data):
    dictionary, word = {0: ''}, 0
    dynamic_dictionary = lambda dictionary, key: dictionary.get(key) or dictionary.__setitem__(key,
                                                                                               len(dictionary)) or 0
    return [token for char in data for token in [(word, char)] for word in [dynamic_dictionary(dictionary, token)] if
            not word] + [(word, '')]


def decompress(data):
    dictionary, j = {0: ''}, ''.join
    dynamic_dictionary = lambda dictionary, value: dictionary.__setitem__(len(dictionary), value) or value
    return j([dynamic_dictionary(dictionary, dictionary[codeword] + char) for (codeword, char) in data])


if __name__ == '__main__':
    data = "ABBCBCABABCAABCAAB"
    compress_data = compress(data)
    decompress_data = decompress(compress_data)

    print 'DATA:', data
    print 'COMPRESSING:', compress_data
    print 'DECOMPRESSING:', decompress_data

I get this error while trying to run this..

Traceback (most recent call last):
  File "LZ88.py", line 17, in <module>
    compress_data = compress(data)
  File "LZ88.py", line 6, in compress
    return [token for char in data for token in [(word, char)] for word in [dynamic_dictionary(dictionary, token)] if not word] + [(word, '')]
  File "LZ88.py", line 6, in <listcomp>
    return [token for char in data for token in [(word, char)] for word in [dynamic_dictionary(dictionary, token)] if not word] + [(word, '')]
UnboundLocalError: local variable 'word' referenced before assignment

Can you help?

Use python2 instead of python3.