如何检查Python中的EOF？

Question

如何检查Python中的EOF？我在代码中发现了一个错误，其中分隔符后的最后一个文本块没有添加到返回列表中。或者，也许有更好的方式来表达这个功能？

这里是我的代码：

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

您可能会发现更容易使用这个解决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] 

另一种替代方法是使用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

的档案结尾条件只要for语句终止持有 - 似乎minorly解决这个代码最简单的方法（你可以在年底提取text_block.getvalue()如果你想在追加它之前检查它不是空的）。

Answer 3

为什么你需要StringIO的吗？

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 

编辑：修正了功能，其他建议可能会更好，只是想写一个类似于原来的功能。

编辑：“ - - ”假定文件开头，加入空字符串到列表中，你可以“修复” IndexError或者你可以用这一个：

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 

但两个版本看起来有点丑陋的我，reg-ex版本更加清洁。

Answer 4

这是标准的问题与发射缓冲器。

你不检测EOF - 这是不必要的。你写最后的缓冲区。

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

这是一个快速的方法，如果你有一个空文件：

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