title: Finding Value in Table and Change Value for all Duplicates
body: <p>I have a dataframe like this</p>
  <pre><code>Subject Special Mutated  
  dog     Y       N      
  dog     Y       N 
  dog     N       Y
  dog     N       Y
  cat     Y       N 
  cat     N       Y
  cat     N       Y 
  bird    N       Y
  bird    N       Y
  </code></pre>
  <p>I want to check if one of the <code>Subject</code> has the value <code>Y</code> in the row <code>Special</code>. If yes, all of the duplicates should get the value <code>Y</code>.</p>
  <p>The Output should look like this</p>
  <pre><code>Subject Special Mutated  
  dog     Y       N      
  dog     Y       N 
  dog     Y       Y
  dog     Y       Y
  cat     Y       N 
  cat     Y       Y
  cat     Y       Y 
  bird    N       Y
  bird    N       Y
  </code></pre>
  <p>i do not have a good approach so far - do any of you have any ideas?</p>