python之key 错误 : '\\documentclass'_编程设计

我有以下 Python 脚本:

import nltk 
from nltk.probability import FreqDist 
nltk.download('punkt') 
 
frequencies = {} 
book = open('book.txt') 
read_book = book.read() 
words = nltk.word_tokenize(read_book) 
frequencyDist = FreqDist(words) 
 
for w in words: 
    frequencies[w] = frequencies[w] + 1  
 
print (frequencies)

当我尝试运行脚本时，我得到以下信息:

[nltk_data] Downloading package punkt to /home/abc/nltk_data... 
[nltk_data]   Package punkt is already up-to-date! 
Traceback (most recent call last): 
  File "test.py", line 12, in <module> 
    frequencies[w] = frequencies[w] + 1  
KeyError: '\\documentclass'

我做错了什么？而且，我怎样才能打印这个词和它在文本文件中出现的次数。

您可以从here 下载book.txt .

请您参考如下方法:

您的 frequencies 字典是空的。您从一开始就遇到关键错误，这是意料之中的。

我建议您改用 collections.Counter。它是一个专门的字典(有点像 defaultdict)，可以计算出现次数。

import nltk,collections 
from nltk.probability import FreqDist 
nltk.download('punkt') 
 
frequencies = collections.Counter() 
with open('book.txt') as book: 
    read_book = book.read() 
words = nltk.word_tokenize(read_book) 
frequencyDist = FreqDist(words) 
 
for w in words: 
    frequencies[w] += 1  
 
print (frequencies)

编辑:这回答了你的问题，根本没有使用 ntlk 包。我的回答就像 nltk 包只是一个字符串分词器。因此，为了更具体并允许在不重新发明轮子的情况下进一步进行文本分析，并且感谢下面的各种评论，您应该这样做:

import nltk 
from nltk.probability import FreqDist 
nltk.download('punkt') 
 
with open('book.txt') as book: 
    read_book = book.read() 
words = nltk.word_tokenize(read_book) 
frequencyDist = FreqDist(words)   # no need for the loop, does the count job 
 
print (frequencyDist)

你会得到(用我的文字):

<FreqDist with 142 samples and 476 outcomes>

所以不是直接包含 word => 元素数量的字典，而是包含此信息的更复杂的对象 + 更多信息:

frequencyDist.items():你得到 words=>count(和所有经典的 dict 方法)
frequencyDist.most_common(50) 打印 50 个最常见的词
frequencyDist['the'] 返回 "the" 的出现次数
...