每天一个小程序—0004题（统计单词出现次数）

第 0004 题： 任一个英文的纯文本文件，统计其中的单词出现的个数。

先给出我一开始写得，只能说非常不优美，一个一个字符搞得。。。

f = open('num.txt')
word = []
word_num = {}
char = f.read(1)
while char:
    if char == ' ' or char == '
':
        if word:
            word = ''.join(word).lower()  #转成小写
            if word in word_num:
                word_num[word] += 1
            else:
                word_num[word] = 1
            word = []
    else:
        word.append(char)
    char = f.read(1)
if word:
    word = ''.join(word).lower()
    if word in word_num:
        word_num[word] += 1
    else:
        word_num[word] = 1
    word = []
for i,j in word_num.items():
    print(i,j)

第二次看了网上的，开始尝试用正则表达式来搞：

import re

f = open('num.txt')
word_list = []
reg = 'w+'   #/w是匹配字母、数字、下划线

for line in f:
    word = re.findall(reg, line)    #也可以是word = line.split() 
    word_list.extend(word)

word_set = set(word_list)
word_dict = {word: word_list.count(word) for word in word_set}
for i, j in word_dict.items():
    print(i, j)

最后就是python自带的collections模块，里面有Counter计数器函数，可以自动统计单词出现次数。

可以先用个例子来了解一下Counter：

from collections import Counter

word_list = ['I', 'am', 'zyb', 'zyb']
ans = Counter(word_list)
print(ans)

结果为：

代码很简洁，如下：

import re
from collections import Counter

f = open('num.txt')
word_list = []

for line in f:
    word = line.split()
    word_list.extend(word)

word_dict = dict(Counter(word_list))
for i, j in word_dict.items():
    print(i, j)