python怎么计算文档的行数据库

小文件读取，计算行数

1. count = len(open(filepath,'rU').readlines())

大文件读取，计算行数

1. count = -1
      for count, line in enumerate(open(thefilepath, 'rU')):

       pass
   count += 1

1. count = 0
      thefile = open(thefilepath, 'rb')

   while True:
      buffer = thefile.read(8192*1024)
      if not buffer:
         break
      count += buffer.count('n')
   thefile.close( )

读取指定行

import linecache

count = linecache.getline(filename,linenum)