算数编码python实现

参考博客

https://blog.youkuaiyun.com/hanzhen7541/article/details/91142442

https://blog.youkuaiyun.com/zzq060143/article/details/89307513

def get_dict_from_singal():
    singal_dict = {}
    singal_dict['A'] = (0, 0.1)
    singal_dict['B'] = (0.1, 0.5)
    singal_dict['C'] = (0.5, 0.7)
    singal_dict['D'] = (0.7, 1)
    return singal_dict


def encoder(singal, singal_dict):
    Low = 0
    High = 1
    for s in singal:
        CodeRange = High - Low
        High = Low + CodeRange * singal_dict[s][1]
        Low = Low + CodeRange * singal_dict[s][0]
    return Low


def decoder(encoded_number, singal_dict, singal_length):
    singal = []
    while singal_length:
        for k, v in singal_dict.items():
            if v[0] <= encoded_number < v[1]:
                singal.append(k)
                range = v[1] - v[0]
                encoded_number -= v[0]
                encoded_number /= range
                break
        singal_length -= 1
    return singal


def main():
    singal_dict = get_dict_from_singal()
    singal = 'CADACDB'
    ans = encoder(singal, singal_dict)
    print(ans)
    singal_rec = decoder(ans, singal_dict, len(singal))
    print(singal_rec)


if __name__ == '__main__':
    main()