title: Collapsing rows by user with dplyr
body: <p>I want to collapse the rows based on users while placing the '1' on their corresponding columns. </p>
  
  <p>Each row for each user can only have one '1' so there need not be any adding to the rows following. </p>
  
  <p>My df:</p>
  
  <pre><code>User  +1  +2  +3  +4  +5
     A   1   0   0   0   0
     A   0   1   0   0   0
     A   0   0   0   0   1
     B   0   0   1   0   0 
     B   0   0   0   1   0
  </code></pre>
  
  <p>Expected result:</p>
  
  <pre><code>User  +1  +2  +3  +4  +5
     A   1   1   0   0   1
     B   0   0   1   1   0 
  </code></pre>
  
  <p>Any help would be appreciated. </p>