A
Sankey diagram
allows to study flows. Entities (nodes) are represented by rectangles
or text. Arrows or arcs are used to show flows between them. In
`R`

, the `networkD3`

package is the best way to
build them

Step by step

The `networkD3`

package allows to visualize networks using
several kinds of viz. One of its function makes stunning Sankey
diagrams as shown below. Follow the steps below to get the basics and
learn how to customize your Sankey Diagram.

Interactivity

The `networkD3`

package is an htmlwidget: it automatically
builds interactive charts. Check the chart below: you can drag nodes
and hover links for more informagtion. If for some reason you need to
export it to `png`

or `pdf`

, it is possible
thanks to the
webshot
package.

__Note__: The example below comes directly from the networkD3
documentation.

Alluvial diagram

An alluvial chart is a variation of the sankey plot. It visualizes
frequency distributions over time or frequency tables involving
several categorical variables. In `R`

, 2 packages exist to
build an alluvial diagram: `alluvial`

and
`ggalluvial`