python从txt文档中随机抽取n条记录

#coding:utf-8

import random
import time
"""
注意盘符小写

"""
f = open("d:\MyData\zhaohz4\Desktop\train.txt","r")           #源文件
fw = open("d:\MyData\zhaohz4\Desktop\sample_10.txt","w")     #待写文件
"""
如下亦可
f = open("d:/MyData/zhaohz4/Desktop/train.txt","r")
fw = open("d:/MyData/zhaohz4/Desktop/sample_10.txt","w")
"""
def test():  
    start = time.clock()
    raw_list = f.readlines()
    random.shuffle(raw_list)
    for i in range(50):                           #随机抽取数目 n
        fw.writelines(raw_list[i])

    end = time.clock()
    print("cost time is %f" %(end - start))

if __name__ =="__main__":
    test()