如何从 NLTK 扩展停用词列表并使用扩展列表删除停用词？

Question

我尝试了两种删除停用词的方法，但都遇到了问题：

方法一：

cachedStopWords = stopwords.words("english")
words_to_remove = """with some your just have from it's /via & that they your there this into providing would can't"""
remove = tu.removal_set(words_to_remove, query)
remove2 = tu.removal_set(cachedStopWords, query)

在这种情况下，只有第一个删除功能有效。 remove2 不起作用。

方法二：

lines = tu.lines_cleanup([sentence for sentence in sentence_list], remove=remove)
words = '\n'.join(lines).split()
print words # list of words

输出看起来像这样["Hello", "Good", "day"]

我尝试从单词中删除停用词。这是我的代码：

for word in words:
    if word in cachedStopwords:
        continue
    else:
        new_words='\n'.join(word)

print new_words

输出如下所示：

H
e
l
l
o

无法弄清楚上述两种方法有什么问题。请指教。

Answer 1

使用它来增加停用词列表：

from nltk.corpus import stopwords
stop_words = stopwords.words('english')
print(len(stop_words))
stop_words.extend(['from', 'subject', 're', 'edu', 'use'])
print(len(stop_words))

输出：

179

184

Answer 2

我认为您想要实现的是扩展 NLTK 的停用词列表。由于 NLTK 中的停用词保存在一个列表中，您可以简单地这样做：

>>> from nltk.corpus import stopwords
>>> stoplist = stopwords.words('english')
>>> stoplist
[u'i', u'me', u'my', u'myself', u'we', u'our', u'ours', u'ourselves', u'you', u'your', u'yours', u'yourself', u'yourselves', u'he', u'him', u'his', u'himself', u'she', u'her', u'hers', u'herself', u'it', u'its', u'itself', u'they', u'them', u'their', u'theirs', u'themselves', u'what', u'which', u'who', u'whom', u'this', u'that', u'these', u'those', u'am', u'is', u'are', u'was', u'were', u'be', u'been', u'being', u'have', u'has', u'had', u'having', u'do', u'does', u'did', u'doing', u'a', u'an', u'the', u'and', u'but', u'if', u'or', u'because', u'as', u'until', u'while', u'of', u'at', u'by', u'for', u'with', u'about', u'against', u'between', u'into', u'through', u'during', u'before', u'after', u'above', u'below', u'to', u'from', u'up', u'down', u'in', u'out', u'on', u'off', u'over', u'under', u'again', u'further', u'then', u'once', u'here', u'there', u'when', u'where', u'why', u'how', u'all', u'any', u'both', u'each', u'few', u'more', u'most', u'other', u'some', u'such', u'no', u'nor', u'not', u'only', u'own', u'same', u'so', u'than', u'too', u'very', u's', u't', u'can', u'will', u'just', u'don', u'should', u'now']
>>> more_stopwords = """with some your just have from it's /via & that they your there this into providing would can't"""
>>> stoplist += more_stopwords.split()
>>> sent = "With some of hacks to your line of code , we can simply extract the data you need ."
>>> sent_with_no_stopwords = [word for word in sent.split() if word not in stoplist]
>>> sent_with_no_stopwords
['With', 'hacks', 'line', 'code', ',', 'simply', 'extract', 'data', 'need', '.']
# Note that the "With" is different from "with".
# So let's try this:
>>> sent_with_no_stopwords = [word for word in sent.lower().split() if word not in stoplist]
>>> sent_with_no_stopwords
['hacks', 'line', 'code', ',', 'simply', 'extract', 'data', 'need', '.']
# To get it back into a string:
>>> new_sent = " ".join(sent_with_no_stopwords)
>>> new_sent
'hacks line code , simply extract data need .'

Answer 3

你可以改变方法2：

for word in words:
    if word in cachedStopwords:
        continue
    else:
        new_words='\n'.join(word)

print new_words

到：

new_words = []
for word in words:
    if word in stop_words:
        continue
    else:
        new_words.append(word)

print new_words

Answer 4

您需要标记您的字符串：

words = string.split()

这是一种简单的方法，尽管 nltk 有其他标记器。

然后可能是列表理解：

words = [w for w in words if w not in cachedstopwords]

这个：

from nltk.corpus import stopwords

stop_words = stopwords.words("english")
sentence = "You'll want to tokenise your string"

words = sentence.split()
print words
words = [w for w in words if w not in stop_words]
print words

打印：

["You'll", 'want', 'to', 'tokenise', 'your', 'string']
["You'll", 'want', 'tokenise', 'string']