lass="external-link">plot</a></span><span class="op">(</span><span class="va">l</span><span class="op">$</span><span class="va">geometry</span>, col <span class="op">=</span> <span class="fl">2</span><span class="op">:</span><span class="fl">5</span><span class="op">)</span></span></span>
<span class="r-in"><span><span class="va">midpoints</span> <span class="op">=</span> <span class="fu">line_midpoint</span><span class="op">(</span><span class="va">l</span><span class="op">)</span></span></span>
<span clas