title: Generate random strings in pandas
body: <p>I would like to create a string of one million keys with 200 different values: </p>
  
  <pre><code>N = 1000000 
  uniques_keys = [pd.core.common.rands(3) for i in range(200)] 
  keys = [random.choice(uniques_keys) for i in range(N)] 
  </code></pre>
  
  <p>However, I get the following error</p>
  
  <pre><code>In [250]:import pandas as pd 
  
  In [251]:pd.core.common.rands(3)
  Traceback (most recent call last):
  
    File "&lt;ipython-input-251-31d12e0a07e7&gt;", line 1, in &lt;module&gt;
      pd.core.common.rands(3)
  
  AttributeError: module 'pandas.core.common' has no attribute 'rands'
  </code></pre>
  
  <p>I use pandas version 0.18.0.</p>