pre class="downlit sourceCode r">
<code class="sourceCode R"><span><span class="co"># data.table</span></span>
<span><span class="fu"><a href="https://rdrr.io/r/utils/head.html" class="external-link">head</a></span><span class="op">(</span><span class="va">flights</span><span class="op">[</span><span class="va">origin</span> <span class="op">==</span> <span class="st">"JFK"</span> <span class="op">&amp;</span> <span class="va">month</span> <span class="op">==</span> <span class="fl">6L</span><span class="op