在python2中從python3解開OrderedDict

Question

我正在嘗試解開在 python3 中腌制的對象。 這適用於python3但不適用於python2。 該問題可以重現到 pickle 協議 0。示例代碼：

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()

這將產生以下 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.

當我嘗試從 python2 加載在 python3 中創建的 pickle 文件時，出現以下異常：

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，將 pickle 文件中的第一行從 UserString 更改為 collections 可以解決問題。

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)])

這是python3中pickle的錯誤嗎？

Answer 1

確保在 Python 2 中導入collections 。此代碼對我有用：

Python 3 - 進行酸洗：

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 - 進行解壓：

import pickle
import collections

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

當我這樣做時，我可以毫無問題地閱讀o ：

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