ss="sourceCode r"><code class="sourceCode r"><span id="cb12-1"><a href="#cb12-1" tabindex="-1"></a>df <span class="ot">&lt;-</span> <span class="fu">data.frame</span>(<span class="at">x =</span> <span class="fu">c</span>(<span class="dv">1</span>, <span class="dv">2</span>, <span class="dv">3</span>), <span class="at">y =</span> <span class="fu">c</span>(<span class="dv">1</span>, <span class="dv">4</span>, <span class="dv">9</span>))</span>
<span id="cb12-2"><a href="#cb12-2" tabindex="-1"></a></span>
<spa