python实现分割文件

#!/usr/bin/python
# -*- coding: utf-8 -*-

import os

def split_file(filename,size):
fp=open(filename,'rb')
i=0
n=0
dir_put='split_dir/'
if os.path.isdir(dir_put):
pass
else:
os.mkdir(dir_put)
filename_front=os.path.splitext(filename)[0]   #取到除去扩展名的文件名
temp=open(dir_put+filename_front+'.part'+str(i)+'.txt','wb')
buf=fp.read(1024)
while 1:
temp.write(buf)
buf=fp.read(1024)
if buf=='':
print filename_front+'.part'+str(i)+'.txt'
temp.close()
fp.close()
return
n+=1
if n==size:
n=0
print filename_front+'.part'+str(i)+'.txt'
i+=1
temp.close()
temp=open(dir_put+filename_front+'.part'+str(i)+'.txt','wb')
fp.close()

if __name__=='__main__':
filename=raw_input("enter filename:")
size=int(raw_input("enter size:"))   #注意转换为int，否则无效
split_file(filename,size)  #第二个参数的单位是k