-pr">#&gt;</span> 1  1 1, 2, 5, 6</span>
<span class="r-out co"><span class="r-pr">#&gt;</span> 2  2 3, 4, 7, 8</span>
<span class="r-in"><span></span></span>
<span class="r-in"><span><span class="va">x</span> <span class="op">&lt;-</span> <span class="fu"><a href="https://rdrr.io/r/base/data.frame.html" class="external-link">data.frame</a></span><span class="op">(</span> line_id <span class="op">=</span> <span class="fl">1</span><span class="op">:</span><span class="fl">2</span>, x <span class="op">=</span