title: sankey/alluvial diagram with percentage and partial fill in R
body: <p>I would like modify an existing sankey plot using <code>ggplot2</code> and <code>ggalluvial</code> to make it more appealing</p>
  <p>my example is from <a href="https://corybrunson.github.io/ggalluvial/articles/ggalluvial.html" rel="nofollow noreferrer">https://corybrunson.github.io/ggalluvial/articles/ggalluvial.html</a></p>
  <pre class="lang-r prettyprint-override"><code>library(ggplot2)
  library(ggalluvial)
  
  data(vaccinations)
  levels(vaccinations$response) &lt;- rev(levels(vaccinations$response))
  ggplot(vaccinations,
         aes(x = survey, stratum = response, alluvium = subject,
             y = freq,
             fill = response, label = response)) +
    scale_x_discrete(expand = c(.1, .1)) +
    geom_flow() +
    geom_stratum(alpha = .5) +
    geom_text(stat = &quot;stratum&quot;, size = 3) +
    theme(legend.position = &quot;none&quot;) +
    ggtitle(&quot;vaccination survey responses at three points in time&quot;)
  </code></pre>
  <p><img src="https://i.imgur.com/t75yWkx.png" alt="" /></p>
  <p><sup>Created on 2020-10-01 by the <a href="https://reprex.tidyverse.org" rel="nofollow noreferrer">reprex package</a> (v0.3.0)</sup></p>
  <p>Now, I would like to change this plot that it looks similar to a plot from <a href="https://sciolisticramblings.wordpress.com/2018/11/23/sankey-charts-the-new-pie-chart/" rel="nofollow noreferrer">https://sciolisticramblings.wordpress.com/2018/11/23/sankey-charts-the-new-pie-chart/</a>, i.e. 1. change absolute to relative values (percentage) 2. add percentage labels and 3. apply partial fill (e.g. &quot;missing&quot; and &quot;never&quot;)
  <a href="https://i.stack.imgur.com/5DxDJ.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/5DxDJ.png" alt="enter image description here" /></a></p>
  <p><strong>My approach:</strong>
  I think I could change the axis to percentage with something like: <code>scale_y_continuous(label = scales::percent_format(scale = 100))</code>
  However, I am not sure about step 2. and 3.</p>