title: filter and unfilter in dplyr
body: <p>What would be the dplyr analog of performing the following operation in base R?</p>
  
  <pre><code>iris$Sepal.Length[iris$Sepal.Length&gt;2] &lt;- iris$Sepal.Length[iris$Sepal.Length&gt;2] * 10
  </code></pre>
  
  <p>I am trying to use filter but cannot go back to the original data set (without a <code>join</code>)</p>