Sankey charts, also known as flow diagrams, are a powerful tool of data visualization that assist in representing and understanding the flow of data between different categories. From visualizing global energy consumption across different sectors to illustrating the intricate processes flowing through an ecosystems, sankey diagrams offer a rich, intuitive way to depict data movement and interdependencies.
The concept behind Sankey charts revolves around nodes representing entities within a network (such as source, sink, and intermediate entities), with flow lines connecting and linking them. The thickness of these flow lines directly correspond to the volume of interaction or amount of data flow between nodes, providing a visual cue to the viewer for the relative scale of connections.
The construction of a sankey chart isn’t too complicated, but knowing how to read, interpret, and create one requires careful attention to detail. First, every flow starts as a node. These can be anything, from countries, cities, sectors, or even processes. Each node is given a unique value, indicating its role or source of the flow.
Connecting these nodes are arrows or ‘flows.’ These, as mentioned, typically have varying thicknesses, corresponding to the volume of data or product they handle. This is the distinctive feature that makes sankey charts so interesting – the visual emphasis on quantity. If the line connecting two nodes appears much thicker, it means the quantity flowing between them is significantly higher than on thinner lines.
To make a Sankey diagram even more effective, color is frequently used. Different colors for different flows can represent various categories, making it easier for the viewer to distinguish between different streams or segments of data. Adding a legend provides context; the viewer, therefore, can associate colors with designated information.
Layout and orientation are also crucial elements in designing effective Sankey diagrams. A common issue is ‘fuzzing out’ in sankey charts, where the thicker line obscures the shorter lines. This issue can be managed by reordering dimensions, adjusting the thickness of the lines, or optimizing the entire diagram for readability.
Sankey charts are also dynamic in application. They work well not only for quantitative flow data but can also incorporate qualitative data through labels, making them versatile for a wide range of applications, from showing the route of information sharing in knowledge networks to visualizing the trade in commodities between different economies.
In essence, Sankey charts are a powerful visual tool in data storytelling, allowing for the nuanced depiction of flow dynamics in a complex system. These charts are only as valuable as the insights they can provide, and understanding the ins and outs of creating and interpreting them is the key to unlocking those insights.
