title: From list of list, to dataframe with column of lists
body: <p>I have data as follows:</p>
  <pre><code>dat &lt;- structure(
      list( 
          freq = list(a= c(5, 38, 43, 27, 44, 20, 177), b=c(3, 5, 12, 53, 73))), 
      row.names = c(&quot;A&quot;, &quot;B&quot;), class = &quot;data.frame&quot;)
  </code></pre>
  <p>The only thing I want to do is to get a column with the list names, and a column with the lists:</p>
  <pre><code>data.frame:
     rn  values
  1. A   c(5, 38, 43, 27, 44, 20, 177)
  2. B   c(3, 5, 12, 53, 73)
  </code></pre>
  <p>But I just cannot figure it out..</p>
  <p>How should this be done?</p>