Sankey diagrams, also known as Sankey charts, are a unique visualization tool that effectively illustrates the flow of work, materials, energy, or any other type of resource in a process or system. By presenting this flow in a directional form, Sankey charts help to simplify complex data and make it more readily understandable at a glance. This comprehensive guide will take you through the process of creating and interpreting Sankey charts, offering insights into why they are such a valuable resource in various fields.
Understanding the Basics of Sankey Charts
Before diving into the creation and interpretation of Sankey charts, it’s important to grasp the basic principles that underpin this powerful visualization. Sankey diagrams are characterized by a series of parallel branches that represent different processes or elements in a system. Energy, materials, or information flow between these branches, indicated by horizontal lines that diminish or expand according to the magnitude of the flow. The key attributes of a well-crafted Sankey chart include:
– Parallel Branches: Represent different components or categories within a process.
– Width of Lines: Proportional to the quantity of material, energy, or work carried by that portion of the process.
– Directional Flow: Indicates the direction of flow between branches.
– Labeling: Provides clear description of each part of the Sankey diagram.
Creating Your Sankey Chart
Crafting a Sankey chart requires a clear understanding of your data and the process to be visualized. Below are the stages you should follow to make a Sankey chart:
1. Define the Scope: Determine which variables or processes you want to represent in your Sankey chart.
2. Choose Software: Use appropriate software to draw Sankey charts, such as D3.js, Excel, or specialized tools like Sankey Diagrams and Sankey Diagram Canvas.
3. Mapping the System: Begin by sketching out the system with parallel branches. Assign a unique node for each process or component.
4. Identify and Measure the Flows: Accurately assess and determine the actual quantities or energy outputs for each process in the system.
5. Connect Flows: Start at the source, draw a horizontal line to show the input material or energy entering a process. Continue along a branch for the duration of that process. As the process reaches a junction, branch out to each subsequent step and adjust the line width to represent the magnitude of the flow.
6. Finalize the Chart: Fill in branches and labels according to the system and processes you’ve visualized. Ensure the chart is balanced and easy to read.
Interpreting Sankey Charts
Here are some tips for effectively interpreting Sankey charts:
– Focus on Branch Width: The width of a branch conveys the total quantity of flow through that element—a wider branch implies a greater relative flow.
– Analyze Flow Direction: Flow direction indicates where the power or material is flowing between processes, providing insights into system dependencies and efficiency.
– Look for Deadends and Loops: Deadends suggest a disconnect or a process that doesn’t directly contribute to output, while loops may indicate a process with potential for optimization or inefficiency.
– Compare Across Charts: If you have multiple Sankey diagrams, compare them to look for patterns or differences in the same or comparable data.
Sankey charts serve as a versatile and informative tool, helping you not only to understand, but also to optimize and communicate complex systems. With this guide, you can now embark on creating your Sankey chart with a solid foundation, confident in your ability to visualize data in a truly unique way.
