Python：KeyError：“ it”

Question

我正在尝试在python3中使用nltk进行URL文本摘要，但是我不确定为什么它显示KeyError。 这是我的代码：

flasexam.py

import bs4 as bs
import urllib.request
import re
import heapq
import nltk

scraped_data = urllib.request.urlopen('https://en.wikipedia.org/wiki/Machine_learning')
article = scraped_data.read()

parsed_article = bs.BeautifulSoup(article,'lxml')

paragraphs = parsed_article.find_all('p')

article_text = ""

for p in paragraphs:
    article_text += p.text

article_text = re.sub(r'\[[0-9]*\]', ' ', article_text)
article_text = re.sub(r'\s+', ' ', article_text)

formatted_text = re.sub('[^a-zA-Z]', ' ', article_text)
formatted_text = re.sub(r'\s+', ' ', formatted_text)

sentence_list = nltk.sent_tokenize(article_text)

stopwords = nltk.corpus.stopwords.words('english')

word_freq = {}
for word in nltk.word_tokenize(formatted_text):
    if word not in stopwords:
        if word not in word_freq.keys():
            word_freq[word] = 1
        else:
            word_freq[word] += 1

max_freq = max(word_freq.values())
for word in word_freq.keys():
    word_freq[word] = (word_freq[word]/max_freq)

sentence_scores = {}
for sent in sentence_list:
    for word in nltk.word_tokenize(sent.lower()):
        if len(sent.split(' ')) < 30:
            if sent not in sentence_scores.keys():
                sentence_scores[sent] = word_freq[word]
            else:
                sentence_scores[sent] += word_freq[word]

summary_sentences = heapq.nlargest(7, sentence_scores, key=sentence_scores.get)

summary = ' '.join(summary_sentences)
print(summary)

在运行此代码时，它显示此错误：

Traceback (most recent call last):
  File "flasexam.py", line 46, in <module>
    sentence_scores[sent] = word_freq[word]
KeyError: 'it'

我不确定确切的错误是什么以及如何解决该错误。

Answer 1

将word_freq[word]替换为：

if word in word_freq:
    word_freq[word] ...

Answer 2

每当请求dict（）对象（使用a = adict [key]格式）并且密钥不在字典中时，Python都会引发KeyError。

In [8]: a = {"name":"Daka", "sex":"male"}

In [9]: a["name"]
Out[9]: 'Daka'

In [10]: a["name_bla"]
---------------------------------------------------------------------------
KeyError                                  Traceback (most recent call last)
<ipython-input-10-91fb451c1e47> in <module>()
----> 1 a["name_bla"]

KeyError: 'name_bla'

简单地说-您正在寻找不在字典中的键“ it”。