这是我的个人文件类;-)
class File(file): """ An helper class for file reading """ def __init__(self, *args, **kwargs): super(File, self).__init__(*args, **kwargs) self.BLOCKSIZE = 4096 def head(self, lines_2find=1): self.seek(0) #Rewind file return [super(File, self).next() for x in xrange(lines_2find)] def tail(self, lines_2find=1): self.seek(0, 2) #Go to end of file bytes_in_file = self.tell() lines_found, total_bytes_scanned = 0, 0 while (lines_2find + 1 > lines_found and bytes_in_file > total_bytes_scanned): byte_block = min( self.BLOCKSIZE, bytes_in_file - total_bytes_scanned) self.seek( -(byte_block + total_bytes_scanned), 2) total_bytes_scanned += byte_block lines_found += self.read(self.BLOCKSIZE).count('n') self.seek(-total_bytes_scanned, 2) line_list = list(self.readlines()) return line_list[-lines_2find:] def backward(self): self.seek(0, 2) #Go to end of file blocksize = self.BLOCKSIZE last_row = '' while self.tell() != 0: try: self.seek(-blocksize, 1) except IOError: blocksize = self.tell() self.seek(-blocksize, 1) block = self.read(blocksize) self.seek(-blocksize, 1) rows = block.split('n') rows[-1] = rows[-1] + last_row while rows: last_row = rows.pop(-1) if rows and last_row: yield last_row yield last_row用法示例：
with File('file.name') as f: print f.head(5) print f.tail(5) for row in f.backward(): print row
