title: Detecting the differences between two string vectors
body: <p>I've got a <code>data_frame</code> that looks like this.</p>
  
  <pre><code>df &lt;- data_frame(name = c('john','bill','amy'),
             name.2 = c('johhn','ball','ammy')) 
  df
  # A tibble: 3 x 2
     name name.2
    &lt;chr&gt;  &lt;chr&gt;
  1  john  johhn
  2  bill   ball
  3   amy   ammy
  </code></pre>
  
  <p>I want to add a column that shows the difference between the two name(.2) columns. Like this:</p>
  
  <pre><code>df %&gt;% 
  mutate(diff = c('h','a','m')) 
  # A tibble: 3 x 3
     name name.2  diff
    &lt;chr&gt;  &lt;chr&gt; &lt;chr&gt;
  1  john  johhn     h
  2  bill   ball     a
  3   amy   ammy     m
  </code></pre>
  
  <p>I'd prefer to find a solution that uses elements of <code>tidyverse</code> and <code>stringr</code> if possible, but I'll take it like I get it. </p>