title: Python: Add random number to filename (without repeating a number)
body: <p>I have a folder with up to 1000 files and I want to add a random number to each of the files without repeating any number. </p>
  
  <p>My files look like this:</p>
  
  <pre><code>file_a.jpg
  file_b.jpg 
  file_c.jpg 
  file_d.jpg
  </code></pre>
  
  <p>and I want them to be like this:</p>
  
  <pre><code>3_file_a.jpg
  1_file_b.jpg
  4_file_c.jpg
  2_file_d.jpg
  </code></pre>
  
  <p>This is my code snippet so far, but using random.sample() seems not to be the right solution. At the moment it creates a list of random variables, which are non repeating, but it creates a new list for each filename. Instead of just one non-repeating number per filename.
  Might be a dumb question, but I am new to python and couldn't figure it out yet how to do this properly.</p>
  
  <pre><code>import os
  from os import rename
  import random
  
  os.chdir('C:/Users/......')
  
  for f in os.listdir():  
     file_name, file_ext = os.path.splitext(f)    
     #file_name = str(random.sample(range(1000), 1)) + '_' + file_name 
     print(file_name) 
     new_name = '{}{}'.format(file_name, file_ext)    
     os.rename(f, new_name)
  </code></pre>