title: Extracting a list from inside a cell in a dataframe
body: <p>I have a dataframe in which a column has a list of values. For example</p>
  
  <pre><code>    created      values
  0   2016-12-21   [1,2,3,4]
  1   2016-12-28   [6,7,8,9]
  2   2017-01-4   [13,12,11,10]
  </code></pre>
  
  <p>Say I want to extract the last value in the row column in a different <code>list(13,12,11,10)</code>. I have written some code using the <code>iloc[]</code> function which looks like below, but I am getting the error</p>
  
  <blockquote>
    <p>TypeError: unhashable type: 'list'</p>
  </blockquote>
  
  <pre><code>i=0
  c=[]
  while value in a['values']:
      i=i+1
      c=a['values'].iloc[i]    
  c
  </code></pre>
  
  <p>Below is the stack trace</p>
  
  <pre><code>TypeError                                 Traceback (most recent call last)
  &lt;ipython-input-18-a6f26f30f73d&gt; in &lt;module&gt;()
        2 user_id=[]
        3 c=[]
  ----&gt; 4 while user_id in a['user_ids']:
        5     i=i+1
        6     c=a['user_ids'].iloc[i]
  
  C:\Users\aditya\Anaconda3\lib\site-packages\pandas\core\generic.py in             __   contains__(self, key)
      844     def __contains__(self, key):
      845         """True if the key is in the info axis"""
  --&gt; 846         return key in self._info_axis
      847 
      848     @property
  
  C:\Users\aditya\Anaconda3\lib\site-packages\pandas\indexes\base.py in    _     _   contains__(self, key)
     1232 
     1233     def __contains__(self, key):
  -&gt; 1234         hash(key)
     1235         # work around some kind of odd cython bug
     1236         try:
  
  TypeError: unhashable type: 'list'
  </code></pre>