title: sum of elements in a list column in r
body: <p>I have a dataset with a column of lists of numbers. I want to mutate a column that has the sum of elements of each row's list. I tried this:</p>
  <pre><code>data %&gt;% mutate(duration_sum = sum(unlist(Durations)))
  </code></pre>
  <p>But the duration_sum column values are all NA. Why is that and how can I fix this?</p>