en a dataset with alluvial structure, <code>stat_alluvium</code> calculates the
centroids (<code>x</code> and <code>y</code>) and heights (<code>ymin</code> and <code>ymax</code>) of the lodes, the
intersections of the alluvia with the strata. It leverages the <code>group</code>
aesthetic for plotting purposes (for now).</p>
    </div>

    <div class="section level2">
    <h2 id="ref-usage">Usage<a class="anchor" aria-label="anchor" href="#ref-usage"></a></h2>
    <div class="sourceCode"><pre class="source