Flow Visualized! The Versatile Art of Sankey Charts

Introduction

In a world where data piles up, understanding its flow can often be a challenge. Sankey charts have emerged as a powerful tool, bridging the gap between complex datasets and intuitive visualization. This versatile artform, while having been in existence since the mid-19th century, continues to evolve and find new applications across a myriad of fields. In this article, we’ll explore the creation of Sankey charts, their unique properties, and some fascinating applications you may not have considered.

What Are Sankey Charts?

Sankey charts are flow diagrams, named after their inventor, William Playfair, and later popularized by Edward Sankey in the late 19th century. These diagrams use arrows to represent the flow of quantities or units from one process, storage, or decision point to another. They are distinct from other types of diagrams for one key reason: the width of the arrows, which are fat or thin, directly reflects the magnitude of the flow of units.

Key Features of Sankey Charts

Flow Representation: The width of the arrows visually communicates the quantity of flow. Thicker arrows signify more extensive flows.
Energy Transfer: Sankey charts are often used to illustrate the energy flows within a system, making them ideal for depicting efficiency and loss.
Directional Flow: Arrows show the direction of flow, allowing the viewer to track the movement of units from source to destination.
Cumulative Sum: The area under the stream of a Sankey chart can represent the cumulative sum, a property that is useful for showing the total flow over time.

Creating Sankey Charts

Creating Sankey charts may seem like an arduous task, but with the right tools, it can be both straightforward and engaging. Here’s a general approach to creating one:

Choose the Data: Select your dataset and gather the information you want to visualize. This data could involve energy flow, water usage, or even the flow of funds in and out of a project.
Define the Nodes: Each arrow’s starting and ending points are nodes. These represent the sources and destinations of the flows. In Sankey charts, the nodes are typically at the beginning and end of the flows, with arrows connecting them.
Determine the Width of Streams: The widths of the arrows are determined by the magnitude of each unit of the flow. The area beneath an arrow represents the total flow of that quantity.
Layout the Diagram: Using a tool such as Microsoft Excel, Google Sheets, or a dedicated software, arrange the nodes and streams. Tools like Graphviz, Gephi, or custom JavaScript libraries such as d3 Sankey can help in achieving a visually appealing layout.
Analyze the Visualization: Once you have finished laying out the Sankey chart, take a moment to digest the information it presents. The chart should reveal patterns and inefficiencies in the system at a glance.

Applications of Sankey Charts

Sankey charts have found uses across numerous domains:

Energy Systems: Visualizing energy flow in manufacturing and building processes to identify inefficiencies and optimize energy consumption.
Ecological Systems: Illustrating the flow of nutrients, water, carbon, and other elements in ecosystems.
Financial Data: Mapping the flow of funds in and out of organizations for budget analysis.
Supply Chains: Depicting the materials, products, and services that are transported in and out of a company or region.

Conclusion

The versatile Sankey chart is a testament to the power of visual storytelling when it comes to complex data. It serves as a concise, effective language for telling stories about the flow and interconnectivity of modern systems. As we continue to delve deeper into data-driven decision-making, the art and science of Sankey chart creation are sure to play an increasingly critical role in how we interpret and use our data.

SankeyMaster

SankeyMaster is your go-to tool for creating complex Sankey charts . Easily enter data and create Sankey charts that accurately reveal intricate data relationships.