Sankey diagrams, often colloquially referred to as Sankey charts, are a unique and powerful tool for visualizing and understanding the flow of materials, energy, or expenditures within complex systems. Their distinctive design, which utilizes streams of varying widths to demonstrate the volume of the flow, has garnered them widespread acclaim in fields such as engineering, environmental science, and finance. This comprehensive guide will walk you through the ins and outs of creating Sankey charts, from understanding their underlying principles to effectively utilizing these powerful visuals to convey complex information.
### Understanding Sankey Diagrams
To appreciate the full potential of Sankey charts, it’s important to understand how they work. At their core, Sankey charts are flow diagrams that are used to visualize the transport or flux of energy, materials, or cost. The thickness of the arrows or streams in the chart represents the quantity flowing, with the narrowest point indicating the least amount of flow and the widest point signifying the greatest.
### Components of a Sankey Chart
1. **Streams**: These are the main visual elements of Sankey charts, representing the flow of materials, energy, cost, or other entities.
2. **Nodes**: These are the starting and ending points of the streams, and they represent the processes, components, or sources/sinks involved in the system.
3. **Arrows**: The orientation and direction of arrows from node to node signify the flow from one aspect to another.
4. **Scale**: The size of the streams is typically proportional to the amount of energy, material, or cost involved, providing clear information on the overall system load and efficiency.
### Creating Your Sankey Chart
#### 1. Define the Data Structure
Before delving into software, outline your data and identify the connections between the components. This data structure will determine the organization of your Sankey chart.
#### 2. Select a Sankey Diagram Software
Numerous tools are available for creating Sankey charts:
– **Open-Source Tools**: Software like GnuPlot and R can help you create Sankey diagrams.
– **Commercial Packages**: Microsoft Visio and Excel offer pre-built Sankey diagram templates.
Alternatively, dedicated Sankey diagram software such as yEd Graph Editor or Sankey Diagrams Excel Template may be more straightforward for complex or visually intricate flow charts.
#### 3. Design the Basic Layout
Here you’ll enter your data and the relationship between elements. Ensure your legend, labels, and title clearly communicate what the chart represents.
#### 4. Customize the Style
Use the stream’s width to represent the flow quantity—a thin stream signifies a low flow, while a broad stream conveys a substantial one. Use color coding to differentiate between various flows or types of energy, making the chart visually rich without being cluttered.
### Best Practices for Sankey Charts
– **Start Simple**: Begin with the minimum amount of information. Add more streams and data once you have a grasp on the essential features.
– **Choose the Right Scale**: Since the flow amount is represented by the stream width, ensure your scales are properly adjusted to convey the data accurately.
– **Consider the Context**: Before publishing your Sankey chart, ensure it provides useful insights, emphasizes the key information, and tells a coherent story without overwhelming the viewer.
– **Stay Organized**: Keep the layout clear, ensuring there are no abrupt changes in width which might lead to misinterpretation of flows.
### Wrapping Up
Sankey diagrams are a fantastic way to visualize what’s often invisible in data visualization: the true flow in systems. With the right planning and tools, you can create impressive Sankey charts that not only convey the message clearly but also attract interest and stimulate discussion. As you create your next Sankey chart, remember the importance of data clarity, context, and visual storytelling to achieve maximum impact.
