title: How to get the sum of combinations of variables of 2 columns in a tibble in r
body: <pre><code>     1       2     3       4              5
   1  2013     A     B      513            513         
   2  2013     B     A      533            524         
   3  2013     B     A      541            540         
   4  2013     B     A      544            532        
   5  2013     E     B      554            540       
   6  2014     F     B      557            558      
   7  2014     F     A      553            604       
       
  </code></pre>
  <p>I have a tibble like that. How I can get the sum of every combination of the columns 2 and 3? So that I get 1 for A and B, 3 for B and A, 1 for E and B and so on.</p>