title: printing one element of a dataframe in a magrittr pipe
body: <p>Consider this simple example</p>
  
  <pre><code>library(dplyr)
  library(glue)
  library(magrittr)
  
  &gt; mydata &lt;- data_frame(value = c(1,2,3))
  &gt; mydata
  # A tibble: 3 x 1
    value
    &lt;dbl&gt;
  1    1.
  2    2.
  3    3.
  </code></pre>
  
  <p>I would like to print the second element of my column <code>value2</code> in my dataframe from within a <code>magrittr</code> pipe. </p>
  
  <p>I know I can exploit the <code>tee</code> operator in <code>magrittr</code>, but as you can see below my code does not work: </p>
  
  <ol>
  <li>it does not print anything </li>
  <li>it does not extract the value itself. Indeed<code>"the second element of value2 is 1"</code> is merely a string. I also tried some variants with <code>glue::"the second element of {} is {}"</code> without success.</li>
  </ol>
  
  <p>For instance,</p>
  
  <pre><code>&gt; mydata %&gt;% mutate(value2 = value - 1) %T&gt;% 
      print('the second element of value2 is 1') %&gt;% 
      summarize(count = n())
  # A tibble: 3 x 2
    value value2
    &lt;dbl&gt;  &lt;dbl&gt;
  1    1.     0.
  2    2.     1.
  3    3.     2.
  # A tibble: 1 x 1
    count
    &lt;int&gt;
  1     3
  </code></pre>
  
  <p>Any ideas how to do that programmatically?
  Thanks!</p>