title: Count occurences of a row with pandas in python
body: <p>I have a pandas data frame with thousands of rows and 4 columns. i.e.:</p>
  
  <pre><code>A B C D 
  1 1 2 0
  3 3 2 1
  3 1 1 0
  ....
  </code></pre>
  
  <p>Is there any way to count how many times a certain row occurs? For example how many times can [3,1,1,0] be found, and return the indices of those rows?</p>