python 生成随机长度的字符串

import os
def randomString(n):
    return (''.join(map(lambda xx:(hex(ord(xx))[2:]),os.urandom(n))))[0:10000]

print randomString(16)

f = open('/home/noone/workspace/xiangqianzu/text.txt','w')

for x in range(10001):
　　f.write(randomString(x)+' ')

f.close()