如何檢查Python中的EOF？

Question

如何檢查Python中的EOF？我在代碼中發現了一個錯誤，其中分隔符後的最後一個文本塊沒有添加到返回列表中。或者，也許有更好的方式來表達這個功能？

這裏是我的代碼：

def get_text_blocks(filename): 
    text_blocks = [] 
    text_block = StringIO.StringIO() 
    with open(filename, 'r') as f: 
     for line in f: 
      text_block.write(line) 
      print line 
      if line.startswith('-- -'): 
       text_blocks.append(text_block.getvalue()) 
       text_block.close() 
       text_block = StringIO.StringIO() 
    return text_blocks 

Answer 1

您可能會發現更容易使用這個解決itertools.groupby。

def get_text_blocks(filename): 
    import itertools 
    with open(filename,'r') as f: 
     groups = itertools.groupby(f, lambda line:line.startswith('-- -')) 
     return [''.join(lines) for is_separator, lines in groups if not is_separator] 

另一種替代方法是使用regular expression匹配隔板：

def get_text_blocks(filename): 
    import re 
    seperator = re.compile('^-- -.*', re.M) 
    with open(filename,'r') as f: 
     return re.split(seperator, f.read()) 

Answer 2

的檔案結尾條件只要for語句終止持有 - 似乎minorly解決這個代碼最簡單的方法（你可以在年底提取text_block.getvalue()如果你想在追加它之前檢查它不是空的）。

Answer 3

爲什麼你需要StringIO的嗎？

def get_text_blocks(filename): 
    text_blocks = [""] 
    with open(filename, 'r') as f: 
     for line in f: 
      if line.startswith('-- -'): 
       text_blocks.append(line) 
      else: text_blocks[-1] += line   
    return text_blocks 

編輯：修正了功能，其他建議可能會更好，只是想寫一個類似於原來的功能。

編輯：「 - - 」假定文件開頭，加入空字符串到列表中，你可以「修復」 IndexError或者你可以用這一個：

def get_text_blocks(filename): 
    text_blocks = [] 
    with open(filename, 'r') as f: 
     for line in f: 
      if line.startswith('-- -'): 
       text_blocks.append(line) 
      else: 
       if len(text_blocks) != 0: 
        text_blocks[-1] += line   
    return text_blocks 

但兩個版本看起來有點醜陋的我，reg-ex版本更加清潔。

Answer 4

這是標準的問題與發射緩衝器。

你不檢測EOF - 這是不必要的。你寫最後的緩衝區。

def get_text_blocks(filename): 
    text_blocks = [] 
    text_block = StringIO.StringIO() 
    with open(filename, 'r') as f: 
     for line in f: 
      text_block.write(line) 
      print line 
      if line.startswith('-- -'): 
       text_blocks.append(text_block.getvalue()) 
       text_block.close() 
       text_block = StringIO.StringIO() 
     ### At this moment, you are at EOF 
     if len(text_block) > 0: 
      text_blocks.append(text_block.getvalue()) 
     ### Now your final block (if any) is appended. 
    return text_blocks 

Answer 5

def get_text_blocks(filename): 
    text_blocks = [] 
    text_block = StringIO.StringIO() 
    with open(filename, 'r') as f: 
     for line in f: 
      text_block.write(line) 
      print line 
      if line.startswith('-- -'): 
       text_blocks.append(text_block.getvalue()) 
       text_block.close() 
       text_block = StringIO.StringIO() 
     ### At this moment, you are at EOF 
     if len(text_block) > 0: 
      text_blocks.append(text_block.getvalue()) 
     ### Now your final block (if any) is appended. 
    return text_blocks 

Answer 6

這是一個快速的方法，如果你有一個空文件：

if f.read(1) == '': 
print "EOF" 
f.close()