Python 3.7 错误：不支持的 Pickle 协议 5

Question

我正在尝试从 RLLib 恢复腌制的配置文件（json 没有如本文所示那样工作），并收到以下错误：

config = pickle.load(open(f"{path}/params.pkl", "rb"))

---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-28-c964561b863c> in <module>
----> 1 config = pickle.load(open(f"{path}/params.pkl", "rb"))

ValueError: unsupported pickle protocol: 5

Python 版本 = 3.7.0

如何在 3.7 中打开此文件？

Answer 1

使用pickle5或将其加载到python 3.8+中，然后使用协议参数将其序列化为较低版本。

Answer 2

对于在python 3.8中使用协议5将数据帧保存到pickle文件并需要将其加载到仅支持协议4的python 3.6的pandas用户（我在看你的google colab）：

!pip3 install pickle5
import pickle5 as pickle
with open(path_to_protocol5, "rb") as fh:
  data = pickle.load(fh)

也可以从python 3.6保存到protocol-4 pickle

data.to_pickle(path_to_protocol4)

更新：如果在从 stable-baselines3 加载模型时遇到这个：

!pip install --upgrade --quiet cloudpickle pickle5
from stable_baselines3 import PPO
# restart kernel if in jupyter notebook

# Might not need this dict in all cases
custom_objects = {
    "lr_schedule": lambda x: .003,
    "clip_range": lambda x: .02
}
model = PPO.load("path/to/model.zip", custom_objects=custom_objects)

2021-05-31 使用 env 测试：

cloudpickle: 1.6.0
pickle5: 0.0.11 
stable-baselines3: 1.0

参考：https : //brainsteam.co.uk/2021/01/14/pickle-5-madness-with-mlflow/