title: Finding pairwise overlap in columns in pandas dataframe
body: <p>I have a dataframe as shown below</p>
  
  <pre><code>| FName | F1 |  F2 | F3| 
  | A     | 0  |  1  | 1 |
  | B     | 1  |  0  | 1 |
  | C     | 1  |  0  | 0 |
  | D     | 1  |  1  | 1 |
  </code></pre>
  
  <p>From here I need to find the count of pairwise set intersection for each of the columns, i.e F1-F2 is 1 , F1-F3 is 2, F2-F3 is 2 and so on. </p>
  
  <p>One obvious method is to convert each series into the <code>set</code> datastructure and then take set intersection followed by length of the resulting set. But is there way in pandas by which the same can be achieved?</p>