替換文件

Question

中的所有行[fromString，toString]我想用給定的字符串替換我的文本文件中的某段文本。例如，給出下面的文件內容：

1 
---From here--- 
2 
---To here--- 
3 

我想編寫在以這種方式的格式開始一個python函數：

replaceSection('pathToFile','---From here---\n','---To here---\n','Woo Hoo!\n') 

這應該在原始文件更改爲：

1 
Woo Hoo! 
3 

我想出了一個簡單的實現（下圖），但我相信它也有一些缺點，我想知道是否有一個更簡單的實現：

• 的代碼很長，這使得它的理解有點麻煩
• 我遍歷了兩次代碼（而不是就地更換） - 這似乎效率不高

• 這是同一個實現我會使用我的C++代碼，我想Python有一些隱藏美女，將使實施更加優雅

  def replaceSection(pathToFile,sectionOpener,sectionCloser,replaceWith = ''): 
      ''' 
      Delete all the lines in a certain section of the given file and put instead a customized text. 
  
      Return: 
      None if a replacement was performed and -1 otherwise. 
      ''' 
      f = open(pathToFile,"r") 
      lines = f.readlines() 
      f.close() 
      if sectionOpener in lines: 
       isWrite = True # while we are outside the block and current line should be kept 
       f = open(pathToFile,"w") 
       #Write each line until reaching a section opener 
       # from which write nothing until reaching the section end. 
       for line in lines : 
        if line == sectionOpener: 
         isWrite = False 
        if isWrite: 
        # We are outside the undesired section and hence want to keep current line  
         f.write(line) 
        else: 
         if line == sectionCloser: 
          # It's the last line of the section 
          f.write(replaceWith) 
          ) 
          isWrite = True 
         else: 
          # Current line is from the block we wish to delete 
          # so don't write it. 
          pass 
       f.flush() 
       f.close() 
      else: 
       return -1 
  

Answer 1

下面是一個itertools基礎的方法：

from itertools import takewhile, dropwhile, chain, islice 

with open('input') as fin, open('output', 'w') as fout: 
    fout.writelines(chain(
     takewhile(lambda L: L != '---From here---\n', fin), 
     ['Woo Hoo!\n'], 
     islice(dropwhile(lambda L: L != '---To here---\n', fin), 1, None) 
     ) 
    ) 

所以，直到我們得到了來自標誌，寫出來的原線，那麼線（S）你想，那麼，不顧一切，直到結束標誌，並寫下其餘的行（跳過第一個，因爲它將是結束標記）...

Answer 2

在這裏你可以隨便找個地方您2種模式是：這個界定文本的一部分，你不得不用你的新模式來替代它：

>>> f = my_file.readlines() 
>>> beg = f.index('---From here---') 
>>> end = f.index('---To here---') + len('---To here---') 
>>> print f.replace(f[beg:end], 'Woo woo !') 
1 
Woo woo ! 
3 

當心你的第二個分隔符的長度（因此f.index('---To here---') + len('---To here---')）的。