title: dplyr Update a cell in a data.frame
body: <pre><code>df &lt;-data.frame(x=c(1:5),y=c(letters[1:5]))
  </code></pre>
  
  <p>Let's say I want to modify the last row, </p>
  
  <pre><code>update.row&lt;-filter(df,x==5) %&gt;% mutate(y="R")
  </code></pre>
  
  <p>How do I update this row into the data.frame ?
  The only way, I found albeit a strange way is to do an 
  anti-join and append the results.</p>
  
  <pre><code>df &lt;-anti_join(df,update.row,by="x") %&gt;%
       bind_rows(update.row)
  </code></pre>
  
  <p>However, it seems like a very inelegant way to achieve a simple task.
  Any ideas are much appreciated...</p>