><span class="kw">data.frame</span>(<span class="dt">ID =</span> <span class="kw">c</span>(<span class="st">&quot;b&quot;</span>,<span class="st">&quot;b&quot;</span>,<span class="st">&quot;b&quot;</span>,<span class="st">&quot;a&quot;</span>,<span class="st">&quot;a&quot;</span>,<span class="st">&quot;c&quot;</span>), <span class="dt">a =</span> <span class="dv">1</span><span class="op">:</span><span class="dv">6</span>, <span class="dt">b =</span> <span class="dv">7</span><span class="op">:</span><span cl