<span class="st">&quot;BE&quot;</span>, <span class="st">&quot;FR&quot;</span>, <span class="st">&quot;DE&quot;</span>)</a>
<a class="sourceLine" id="cb191-3" title="3">df &lt;-<span class="st"> </span><span class="kw">data.frame</span>(</a>
<a class="sourceLine" id="cb191-4" title="4">  <span class="dt">from =</span> countries,</a>
<a class="sourceLine" id="cb191-5" title="5">  <span class="dt">to =</span> <span class="kw">rev</span>(countries),</a>
<a class="sourceLine" id="cb191-6" title="6">  <span clas