"sourceCode" id="cb10"><pre class="sourceCode r"><code class="sourceCode r"><span id="cb10-1"><a href="#cb10-1" aria-hidden="true"></a><span class="co"># check again for &#39;24&#39;</span></span>
<span id="cb10-2"><a href="#cb10-2" aria-hidden="true"></a>flights[, <span class="kw">sort</span>(<span class="kw">unique</span>(hour))]</span>
<span id="cb10-3"><a href="#cb10-3" aria-hidden="true"></a><span class="co">#  [1]  0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23</span></span></c