python实现lz78算法

您好，可以通过以下代码实现lz78算法的压缩和解压缩功能：

压缩：

def lz78_compress(data):
    dictionary = {}
    compressed_data = []
    index = 0
    while index < len(data):
        prefix = ""
        symbol = data[index]
        while prefix + symbol in dictionary and index < len(data)-1:
            prefix += symbol
            index += 1
            symbol = data[index]
        if prefix + symbol not in dictionary:
            dictionary[prefix + symbol] = len(dictionary) + 1
        compressed_data.append(dictionary[prefix + symbol])
        index += 1
    return compressed_data

解压缩：

def lz78_decompress(data):
    dictionary = {1: ""}
    index = 0
    decompressed_data = ""
    while index < len(data):
        if data[index] in dictionary:
            decompressed_data += dictionary[data[index]]
            if index < len(data)-1:
                symbol = data[index+1]
                if symbol in dictionary:
                    dictionary[len(dictionary)+1] = dictionary[data[index]] + dictionary[symbol][0]
            else:
                break
        else:
            symbol = dictionary[data[index]-1] + dictionary[data[index]-1][0]
            decompressed_data += symbol
            dictionary[len(dictionary)+1] = symbol
        index += 1
    return decompressed_data

注意：这里的实现只是示例代码，并没有考虑效率和其他细节问题。实际使用中需要进行优化和改进。