e option <code>quantile_lines = TRUE</code>, we can make
<code>stat_density_ridges</code> calculate the position of lines
indicating quantiles. By default, three lines are drawn, corresponding
to the first, second, and third quartile:</p>
<div class="sourceCode" id="cb16"><pre class="downlit sourceCode r">
<code class="sourceCode R"><span><span class="fu"><a href="https://ggplot2.tidyverse.org/reference/ggplot.html" class="external-link">ggplot</a></span><span class="op">(</span><span class="va">iris</span>