一个程序，它打开一个文本文件，计算字数，并按出现在文件中的次数顺序报告前N个字？

Question

大家好，我是一个编程初学者，我最近被赋予了创建这个程序的任务，我发现它很难。我以前设计过一个程序，计算用户输入的句子中的单词数，是否可以修改这个程序来实现我想要的目标？

import string
def main():
  print "This program calculates the number of words in a sentence"
  print
  p = raw_input("Enter a sentence: ")
  words = string.split(p)
  wordCount = len(words)
  print "The total word count is:", wordCount
main()

Answer 1

使用^{}计算字数，使用open()打开文件：

from collections import Counter
def main():
    #use open() for opening file.
    #Always use `with` statement as it'll automatically close the file for you.
    with open(r'C:\Data\test.txt') as f:
        #create a list of all words fetched from the file using a list comprehension
        words = [word for line in f for word in line.split()]
        print "The total word count is:", len(words)
        #now use collections.Counter
        c = Counter(words)
        for word, count in c.most_common():
           print word, count
main()

collections.Counter示例：

>>> from collections import Counter
>>> c = Counter('aaaaabbbdddeeegggg')

Counter.most_common根据字数按排序顺序返回单词：

>>> for word, count in c.most_common(): 
...     print word,count
...     
a 5
g 4
b 3
e 3
d 3

Answer 2

import re
from collections import Counter

with open('file_name.txt') as f:
    sentence = f.read()

words = re.findall(r'\w+', sentence)
word_counts = Counter(words)

Answer 3

要打开文件，可以使用open函数

from collections import Counter
with open('input.txt', 'r') as f:
    p = f.read() # p contains contents of entire file
    # logic to compute word counts follows here...

    words = p.split()

    wordCount = len(words)
    print "The total word count is:", wordCount

    # you want the top N words, so grab it as input
    N = int(raw_input("How many words do you want?"))

    c = Counter(words)
    for w, count in c.most_common(N):
       print w, count