Introduction:
Sankey diagrams, also known as Sankey flow diagrams, flow charts, or flow diagrams, are a way of visualizing data and data flows in a particularly dynamic and intuitive manner. This type of chart is an indispensable graphic element for explaining complex relationships between different data sets and the interplay of connections such as flows, transfers, or distributions. The guide below aims to provide you with a comprehensive understanding of Sankey diagrams, so you can effectively use these powerful graphic tools. Let’s begin:
Understanding the Basics:
A Sankey diagram is a flow chart of information, materials, energy, etc. It’s a method to represent the quantity of a variable within a system and illustrates how it is distributed or transferred among parts. To create a Sankey diagram, you only need three data types: source, label (or node), and data or flow values. The thickness of the lines (arrows) in a Sankey chart corresponds to the amount of data it represents; the wider the line, the greater the flow.
Creating Your Sankey Diagram:
Creating a Sankey diagram starts with your data organization. For the data to be accurately represented, you need to structure it correctly. Here’s a step-by-step guide:
1. List your categories: Start by identifying your sources, flows, and targets. This is typically your top-down view, meaning your categories include every origin, every movement, and every destination.
2. Input your values: For each connection between a source and destination, input the flow or quantity. This is where you input the data that you want displayed, which corresponds to the width of each connection line in the Sankey chart.
3. Adjust line thickness: The thickness or width of the arrows in your Sankey diagram corresponds directly to the magnitude of the flow represented, giving the viewer an immediate visual cue of which flows are larger or smaller.
4. Label sections: Adding labels helps clarify what your Sankey chart represents. Label every node clearly so that it is easy for the audience to understand the flow dynamics.
5. Design the layout: Aesthetic layout decisions can make your Sankey diagram more intuitive or pleasing to look at. Consider the placement of nodes, the size of your chart, and the overall style to create an organized and readable map.
Common Variations:
Sankey diagrams can take on different forms, each serving different aspects or purposes of data visualization. Some common variations you might encounter include:
1. Horizontal layout: This is especially useful when you have numerous nodes and flows that would be too complex or cluttered in a vertical arrangement.
2. Cascading layout: Used when you want to show the breakdown of a total amount into smaller constituents. It presents a more hierarchical view.
Best Practices:
While creating Sankey diagrams, keep the following tips in mind to ensure your information is communicated effectively:
1. Accuracy: Double-check your data before creating the Sankey diagram. Incorrect information can lead to misleading interpretation.
2. Clarity: Aim for simplicity when using a Sankey diagram. A busy or cluttered chart can be difficult to interpret.
3. Focus on key information: Depending on the complexity of your data, it might be necessary to highlight key flows or focus on specific areas within the chart.
4. Color: Use distinct colors for different data flows. This enhances the visual impact and makes it easier to discern between various lines.
Conclusion:
Mastering the Sankey diagram is a valuable skill for anyone working with data, particularly in scientific, statistical, engineering, and financial contexts. Whether you are analyzing transportation routes, analyzing data flows in systems, or explaining material distribution processes, the right Sankey diagram can make the data easily accessible, interpretable, and compelling. By learning the basics, creating your own charts, and adhering to best practices, you will be well-equipped to effectively use this powerful and visually engaging data visualization tool.
