Python的讀取/寫入

Question

我的程序必須讀取有許多行的文本文件。然後它將 相同的文本複製到輸出文件，除了所有無用的單詞（如「the」，「a」和「an」）被刪除。問題是什麼？

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Answer 1

這裏亞去，只需使用str.replace：

with open("a.txt","r") as fin, open("b.txt","w") as fout: 
    stopList=['the','a','an'] 
    for line in fin: 
     for useless in stopList: 
      line = line.replace(useless+' ', '') 
     fout.write(line) 

如果你不想保存整個文件到內存中，你需要到別的地方寫的結果。但是，如果你不介意的話，你可以把它改寫：

with open("a.txt","r") as fin, open("a.txt","w") as fout: 
    stopList=['the','a','an'] 
    r = [] 
    for line in fin: 
     for useless in stopList: 
      line = line.replace(useless+' ', '') 
     r.append(line) 
    fout.writelines(r) 

演示：

>>> line = 'the a, the b, the c' 
>>> stopList=['the','a','an'] 
>>> for useless in stopList: 
    line = line.replace(useless+' ', '') 


>>> line 
'a, b, c' 

Answer 2

使用regular expression：

import re 

with open('a.txt') as f, open('b.txt','w') as out: 
    stopList = ['the', 'a', 'an'] 
    pattern = '|'.join(r'\b{}\s+'.format(re.escape(word)) for word in stopList) 
    pattern = re.compile(pattern, flags=re.I) 
    out.writelines(pattern.sub('', line) for line in f) 

# import shutil 
# shutil.move('b.txt', 'a.txt')