在python2中加载pickle文件(来自python3) [英] Load pickle file(comes from python3) in python2

问题描述

我有一个泡菜文件，带有

I have a pickle file, with

>>> with open("wikilinks.pickle", "rb") as f:
...     titles, links = pickle.load(f)
... 
>>> len(titles)
13421

我可以在python3中加载它. 但是，当我尝试在python2中加载它时，出现以下消息: 追溯(最近一次通话):

I can load it in python3. However, when I try to load it in python2, I get this message: Traceback (most recent call last):

  File "<stdin>", line 2, in <module>
  File "/usr/lib/python2.7/pickle.py", line 1378, in load
    return Unpickler(file).load()
  File "/usr/lib/python2.7/pickle.py", line 858, in load
    dispatch[key](self)
  File "/usr/lib/python2.7/pickle.py", line 886, in load_proto
    raise ValueError, "unsupported pickle protocol: %d" % proto
ValueError: unsupported pickle protocol: 3

那么如何在python2中加载它呢?

So how to load it in python2?

推荐答案

默认酸洗协议与Python 2中使用的协议不兼容.但是，如果您可以修改生成wikilink.pickle的代码，则可以告诉它使用更早的协议之一( 0、1或2)，Python 2会很好理解的.

The default pickling protocol used by default in Python 3 is incompatible with the protocol used by Python 2. However, if you can modify the code that produces wikilink.pickle, you can tell it to use one of the earlier protocols (0, 1, or 2) which Python 2 will understand just fine.

但是请注意，Python 3字符串将在Python 2中作为Unicode字符串出现，这在某些用例中可能会令人惊讶.

Be warned, though, that Python 3 strings will come up as Unicode strings in Python 2, which may be surprising in some use cases.

$ python3
Python 3.4.1 (default, May 19 2014, 17:23:49) 
[GCC 4.9.0 20140507 (prerelease)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import pickle
>>> pickle.dumps([1, 2, 'abc'], 2)
b'\x80\x02]q\x00(K\x01K\x02X\x03\x00\x00\x00abcq\x01e.'
>>> 
$ python 
Python 2.7.8 (default, Jul  1 2014, 17:30:21) 
[GCC 4.9.0 20140604 (prerelease)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import cPickle
>>> cPickle.loads('\x80\x02]q\x00(K\x01K\x02X\x03\x00\x00\x00abcq\x01e.')
[1, 2, u'abc']

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