title: Create new columns based on unique values of values in pandas
body: <p>I have rows which look like this</p>
  
  <pre><code>zipcode   room_type
  2011      bed
  2012      sofa
  </code></pre>
  
  <p>Every listing presents one airBNB listing. I want to aggregate the data so that I count all the unique values. Every unique value get's its own column and the data is grouped by zipcode. So the result would looking something like this:</p>
  
  <pre><code>zipcode   bed   sofa    ground
  1011      200   36      20
  1012      720   45      89
  </code></pre>
  
  <p>How can I get this result with pandas?</p>