recipe-577433.py 文件源码

def compress(string):
    # Get the unique characters and numeric base.
    unique = set(string)
    base = len(unique)
    # Create a key that will encode data properly.
    key = random.sample(unique, base)
    mapping = dict(map(reversed, enumerate(key)))
    while not mapping[string[-1]]:
        key = random.sample(unique, base)
        mapping = dict(map(reversed, enumerate(key)))
    # Create a compressed numeric representation.
    value = 0
    for place, char in enumerate(string):
        value += mapping[char] * base ** place
    # Return the number as a string with the table.
    return decode(value), bytes(key)