This type of flow diagram represents different forms of changes made in the flow of material, energy, cost, or measurable resources in a certain time-bound. Considering the physical appearance of Alluvial Diagrams and their contribution to the flow, the diagram is named immediately after the alluvial fans found in nature.
Dimensions are assigned to parallel vertical axes. The measure is represented with bars on either axis. The height of a bar represents the size of the category and the height of a flow represents the size of the components contained in both categories connected by the flow.
An Alluvial diagram is a variant of the Parallel Sets but for categorical variables and is often is used to show associations between categorical variables. They allow you to visually display flows between categorical variables and flows over time.
The Alluvial Diagram can be found underneath the special charts section. By drag & dropping it into the canvas, data can be added to the two dataslots ‘category’ and ‘measure’. Let’s focus on each of them, illustrated with an example.
The Category Slot is perfect for dimensions you'd like to group by upon (i.e. hierarchical, datetime, or even numeric data.
The data added to this slot dictates the flow of the Alluvial Diagram, with the data added being visualized from left to right. The first category added can be seen as the origin, the last being the destination, and the data in between being branches in the flow.
In the tutorial example below, we add Category as the origin, with branches on the Year, Company, and our destination being the Product .
Tip: You can reorder the flow by rearranging the data in the slot setting of the chart.
Columns with data type ‘numeric’ are a perfect fit for this slot.
The measure slot defines the numeric value of a category. The higher the value, the thicker the flow of the Alluvial. Different aggregations can be set in order to execute different calculations, e.g. sum, average, count.
IIn the tutorial example below , we use a column containing the Profit of sales data to show the amount of sales per product, per year, per company, per category on our flow.
Tip: Displaying numbers on the flow can be enabled in the charts settings with “Show Node Value”
Charts that are similar to the Alluvial, are the sankey diagram.
If you have further questions on this topic, don’t hesitate to contact us. We are happy to help!