如何打開一個文本文件並同時遍歷多行？

Question

我想打開一個文本文件，並根據下一行對某行進行一些操作。 例如，如果我有以下行：

(a) A dog jump over the fire. 
    (1) A fire jump over a dog. 
(b) A cat jump over the fire. 
(c) A horse jump over a dog. 

我的代碼將是這樣的：

with open("dog.txt") as f: 
    lines = filter(None, (line.rstrip() for line in f)) 

for value in lines: 
    if value has letter enclosed in parenthesis 
     do something 
    then if next line has a number enclosed in parenthesis 
     do something 

編輯：這是我使用的解決方案。

for i in range(len(lines)) : 
    if re.search('^\([a-z]', lines[i-1]) : 
     print lines[i-1] 
    if re.search('\([0-9]', lines[i]) : 
     print lines[i] 

Answer 1

商店前行和流程讀取下一後：

file = open("file.txt") 
previous = "" 

for line in file: 
    # Don't do anything for the first line, as there is no previous line. 
    if previous != "": 
     if previous[0] == "(": # Or any other type of check you want to do. 
      # Process the 'line' variable here. 
      pass 

    previous = line 

file.close() 

Answer 2

你應該使用Python的ITER：

with open('file.txt') as f: 
    for line in f: 
     prev_line = line  # current line. 
     next_line = next(f) # when call next(f), the loop will go to next line. 

     do_something(prev_line, next_line)