import os
import random

rootdir = "d:\\face\\train"
file_names = []
for parent, dirnames, filenames in os.walk(rootdir):  #三个参数：分别返回1.父目录 2.所有文件夹名字（不含路径） 3.所有文件名字
  file_names = filenames
  # for filename in filenames:            #输出文件信息
  #   print("parent is" + parent)
  #   print("filename is:" + filename)
  #   print("the full name of the file is:" + os.path.join(parent, filename))
x = random.randint(0, len(file_names)-1)
print(file_names[x])