nction did not update <code>flights</code> <em>data.table</em> by reference. It doesn’t contain the column <code>speed</code>.</p></li>
<li><p>And <code>ans</code> contains the maximum speed corresponding to each month.</p></li>
</ul>
<p>However we could improve this functionality further by <em>shallow</em> copying instead of <em>deep</em> copying. In fact, we would very much like to <a href="https://github.com/Rdatatable/data.table/issues/617">provide this functionality for <code>v1.9.8</code></a>. We w