在python2中从python3解开OrderedDict

Question

我正在尝试解开在 python3 中腌制的对象。 这适用于python3但不适用于python2。 该问题可以重现到 pickle 协议 0。示例代码：

import pickle
import collections

o = collections.OrderedDict([(1,1),(2,2),(3,3),(4,4)])
f = open("test.pkl", "wb")
pickle.dump(o, f, 0)
f.close()

这将产生以下 pkl 文件：

蟒蛇2：

ccollections
OrderedDict
p0
((lp1
(lp2
I1
aI1
aa(lp3
I2
aI2
aa(lp4
I3
aI3
aa(lp5
I4
aI4
aatp6
Rp7

蟒蛇3：

cUserString
OrderedDict
p0
(tRp1
L1L
L1L
sL2L
L2L
sL3L
L3L
sL4L
L4L
s.

当我尝试从 python2 加载在 python3 中创建的 pickle 文件时，出现以下异常：

Python 2.7.6 (default, Jun 22 2015, 17:58:13) 
[GCC 4.8.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import pickle
>>> f = open("test.pkl", "rb")
>>> p = pickle.load(f)
Traceback (most recent call last):
  File "<stdin>", line 1, 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 1090, in load_global
    klass = self.find_class(module, name)
  File "/usr/lib/python2.7/pickle.py", line 1126, in find_class
    klass = getattr(mod, name)
AttributeError: 'module' object has no attribute 'OrderedDict

但是，将 pickle 文件中的第一行从 UserString 更改为 collections 可以解决问题。

Python 2.7.6 (default, Jun 22 2015, 17:58:13) 
[GCC 4.8.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import pickle
>>> f = open("test.pkl", "rb")
>>> p = pickle.load(f)
>>> p
OrderedDict([(1L, 1L), (2L, 2L), (3L, 3L), (4L, 4L)])

这是python3中pickle的错误吗？

Answer 1

确保在 Python 2 中导入collections 。此代码对我有用：

Python 3 - 进行酸洗：

import pickle
import collections

o = collections.OrderedDict([(1,1),(2,2),(3,3),(4,4)])
with open('/home/bo/Desktop/test.pkl', 'wb') as f:
    pickle.dump(o, f, 2)

Python 2 - 进行解压：

import pickle
import collections

with open('/home/bo/Desktop/test.pkl', 'rb') as f:
    o = pickle.load(f)

当我这样做时，我可以毫无问题地阅读o ：

>>> o
0: OrderedDict([(1, 1), (2, 2), (3, 3), (4, 4)])