title: How to use `stringr` in `dplyr` pipe
body: <p>I am having trouble with this code which attempts to edit some strings in a <code>dplyr</code> pipe. Here is some data that throws the following error. Any ideas?</p>
  
  <pre><code>data_frame(id = 1:5,
             name = c('this and it pretty long is a',
                      'name is a',
                      'so and so and so and so  and so',
                      'this is a',
                      'this is a variabel name')) 
  %&gt;% 
  
  str_trunc(.,
     string = .$name,
     width = 10,
     side='right',
     ellipsis = '')
  </code></pre>
  
  <p>Gives me this error: <code>Error in str_trunc(., string = .$name, width = 10, side = "right", ellipsis = ". . . ") : unused argument (.)</code>.</p>
  
  <p>Thanks.</p>