 the individual elements of the alluvial plot. We add an additional column for <code>width</code>, which has a value of 1/3 hard-coded into <code><a href="../reference/geom_alluvium.html">ggalluvial::geom_alluvium()</a></code>, then split the data frame by group (groups correspond to the individual alluvium polygons). We apply the unexported function <code>ggalluvial:::data_to_xspline()</code> to each element of the list to get the x-spline coordinates. Then, we pass the x-spline coordinates to the function