In summary, four types of charts for displaying flows between categorical data were discussed. Each chart type has its own unique quality for visual storytelling.
An Arc Diagram is useful at mapping 1:1 entity-relationships. Applications of such a chart include plotting the relationships of notes used in Beethoven’s Für Elise, to the character interactions in Les Misérables.
A chord diagram is used to display the strength of inter-relationships between categories. The thicker the chord, the stronger the relationship. One application of a chord diagram considers the relation between the count of words spoken between characters in the TV show Friends.
Sankey charts were shown to plot the multi-flow relationships between categories and can also be used to show the process flows between multi-component systems (e.g a steam engine)
Finally, a sunburst chart is used to plot event sequences and their proportional relationships as part of a wider set of relationships. Whether understanding the page-sequence flows on a website or the sequence of coffee flavours, a sunburst chart can cover it.
For all their differences, each chart types provides a unique way to tell a visual story with categorical data and their associated counts. Let the charts flow.