python nltk 模块正在创建它自己的错误

Question

我的 nltk 有一个错误，它不允许我再打开我以前的项目：

from nltk.corpus import stopwords
from nltk.tokenize import word_tokenize

example_sent = "This is a sample sentence, showing off the stop words filtration."

stop_words = set(stopwords.words('english'))

word_tokens = word_tokenize(example_sent)

filtered_sentence = [w for w in word_tokens if not w in stop_words]

filtered_sentence = []

for w in word_tokens:
    if w not in stop_words:
        filtered_sentence.append(w)

print(word_tokens)
print(filtered_sentence)

当我运行它时，我得到这个错误

File "/Users/nicolas/Desktop/part 1 natural lenguage/stopwords.py", line 1, in <module>
    from nltk.tokenize import sent_tokenize, word_tokenize
  File "/Library/Python/2.7/site-packages/nltk/__init__.py", line 114, in <module>
    from nltk.collocations import *
  File "/Library/Python/2.7/site-packages/nltk/collocations.py", line 37, in <module>
    from nltk.probability import FreqDist
  File "/Library/Python/2.7/site-packages/nltk/probability.py", line 47, in <module>
    from collections import defaultdict, Counter
  File "/Library/Python/2.7/site-packages/nltk/collections.py", line 13, in <module>
    import pydoc
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/pydoc.py", line 56, in <module>
    import sys, imp, os, re, types, inspect, __builtin__, pkgutil, warnings
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/inspect.py", line 39, in <module>
    import tokenize
  File "/Users/nicolas/Desktop/part 1 natural lenguage/tokenize.py", line 1, in <module>
    from nltk.corpus import stopwords
  File "/Library/Python/2.7/site-packages/nltk/corpus/__init__.py", line 64, in <module>
    from nltk.tokenize import RegexpTokenizer
  File "/Library/Python/2.7/site-packages/nltk/tokenize/__init__.py", line 67, in <module>
    from nltk.tokenize.mwe      import MWETokenizer
  File "/Library/Python/2.7/site-packages/nltk/tokenize/mwe.py", line 31, in <module>
    from nltk.util import Trie
  File "/Library/Python/2.7/site-packages/nltk/util.py", line 21, in <module>
    from collections import defaultdict, deque
ImportError: cannot import name defaultdict
iMac-di-Monica:part 1 natural lenguage nicolas$ 

错误并没有在这里结束，它还会影响我使用 nltk 的所有其他项目，当我运行第二个代码时

from nltk.tokenize import sent_tokenize, word_tokenize

EXAMPLE_TEXT = "Hello Mr. Smith, how are you doing today? The weather is great, and Python is awesome. The sky is pinkish-blue. You shouldn't eat cardboard."

print(sent_tokenize(EXAMPLE_TEXT))
print(word_tokenize(EXAMPLE_TEXT))


for i in word_tokenize(EXAMPLE_TEXT) :
    print (i)

我得到了同样的错误，第二个代码之前工作得很好。