转：python_文本文件里面随机抽取若干行，写入新的文本文件里面

转：

#encoding=utf-8

import random

from sets import Set

def copyfile(srcfile, dstfile, linenum):

"""

get linenum different lines out from srcfile at random

and write them into dstfile

"""

result = []

ret = False

try:

srcfd = open(srcfile,'r')

except IOError:

print 'srcfile doesnot exist!'

return ret

try:

dstfd = open(dstfile,'w')

except IOError:

print 'dstfile doesnot exist!'

return ret

srclines = srcfd.readlines()

srclen = len(srclines)

while len(Set(result)) < int(linenum):

s = random.randint(0,srclen-1)

result.append(srclines[s])

for content in Set(result):

dstfd.write(content)

srcfd.close()

dstfd.close()

ret = True

return ret

if __name__ == "__main__":

srcpath = raw_input('input srcfile path')

dstpath = raw_input('input dstfile path')

linenum = raw_input('input linenum')

print copyfile(srcpath,dstpath,linenum)