dict-encoder.py

class LZ(object):

    def __init__(self):
        self.char_dict = list()

    def clean(self):
        self.char_dict = []
        self.char_dict.append('')

    def init_dict(self, string):
        for char in string:
            if char not in self.char_dict:
                self.char_dict.append(char)

    def encode(self, string):
        self.clean()
        self.init_dict(string)
        output = ''
        prefix = ''
        for char in string:
            temp = prefix + char
            if temp in self.char_dict:
                prefix += char
            else:
                output += str(self.char_dict.index(prefix))
                self.char_dict.append(prefix + char)
                prefix = char
        return output


encoder = LZ()
print encoder.encode("ABCABABAA")