nltk：集合导入时出错

Question

我有python 2.7。我试图导入word_tokenize（）并从nltk.tokenize（）发送tokenise（）。这显示错误。

       from collections import defaultdict, deque
ImportError: cannot import name defaultdict 

这似乎是名称冲突。我分别导入了集合并打印出来。它来自python库而不是来自nltk。我该如何解决这个冲突？

P.S。

完整代码

from nltk.tokenize import sent_tokenize, word_tokenize
s = "nltk is for natural language processing.?"
print sent_tokenize(s)
print word_tokenize(s)

错误：

Traceback (most recent call last):
  File "tokenize.py", line 1, in <module>
    from nltk.tokenize import sent_tokenize, word_tokenize
  File "/home/atul/miniconda2/lib/python2.7/site-packages/nltk/__init__.py", line 114, in <module>
    from nltk.collocations import *
  File "/home/atul/miniconda2/lib/python2.7/site-packages/nltk/collocations.py", line 37, in <module>
    from nltk.probability import FreqDist
  File "/home/atul/miniconda2/lib/python2.7/site-packages/nltk/probability.py", line 47, in <module>
    from collections import defaultdict, Counter
  File "/home/atul/miniconda2/lib/python2.7/site-packages/nltk/collections.py", line 13, in <module>
    import pydoc
  File "/home/atul/miniconda2/lib/python2.7/pydoc.py", line 56, in <module>
    import sys, imp, os, re, types, inspect, __builtin__, pkgutil, warnings
  File "/home/atul/miniconda2/lib/python2.7/inspect.py", line 39, in <module>
    import tokenize
  File "/media/atul/New Volume1/project/Sentiment Analysis/tokenize.py", line 1, in <module>
    from nltk.tokenize import sent_tokenize, word_tokenize
  File "/home/atul/miniconda2/lib/python2.7/site-packages/nltk/tokenize/__init__.py", line 67, in <module>
    from nltk.tokenize.mwe      import MWETokenizer
  File "/home/atul/miniconda2/lib/python2.7/site-packages/nltk/tokenize/mwe.py", line 31, in <module>
    from nltk.util import Trie
  File "/home/atul/miniconda2/lib/python2.7/site-packages/nltk/util.py", line 21, in <module>
    from collections import defaultdict, deque
ImportError: cannot import name defaultdict