Sankey charts, named after 19th-century Scottish engineer and economist William Sankey, are a type of flow diagram that visually represents the movement of quantities through a system. These charts are characterized by rectangular nodes that represent sources, sinks, and reservoirs, and arrows that convey the flow between these nodes. The width of the arrows is proportional to the flow rate, providing a powerful visualization tool that can communicate complex data with clarity.

The Power of Sankey Charts: A Brief Overview

Sankey charts excel at illustrating the movement of flows from one state to another, making them invaluable in a variety of fields such as energy consumption, material flows, resource allocation, and data analytics. Their key advantages include:

1. Clarity and Simplicity: By visually emphasizing the size of flows, with the width of the arrows indicating the magnitude of the movement, Sankey charts make it easy to identify which flows are dominant and which are minor.
2. Intuitive Understanding: The visual representation makes it simple for the viewer to grasp the relationships and proportions between different flow components.
3. Comparison: Multiple Sankey diagrams can be used to compare different periods or scenarios, highlighting shifts or changes in flow patterns.
4. Space Efficiency: These charts can convey a wealth of information in a compact space, making them suitable for dense data presentations.

Creating Sankey Charts: A Basic Guide

Creating a Sankey chart involves identifying the key components of your data: the nodes (sources, sinks, and reservoirs) and the flows between them. Here’s a step-by-step guide using a popular data visualization tool, Tableau, as an example:

1. Prepare Your Data:

   • Ensure your data is structured with columns for the names of the nodes (sources and sinks), the direction of the flow between them, and the volume of the flow.

2. Open Tableau:

   • Import your data into Tableau by connecting to the data source or dragging and dropping the data file.

3. Design Your Chart:

   • Drag a dimension onto the Columns shelf to represent the source nodes.
   • Drag another dimension onto the Rows shelf to represent the sink nodes.
   • Create a calculated field to sum the flows passing through each node to determine its size.

4. Add the Actual Flow:

   • Drag a measure (representing the volume of the flow) onto the Size card for the connecting arrows.
   • Drag your calculated field (step 3) onto the Color shelf to define the thickness or width of the lines based on the flow values.

5. Adjust the Layout:

   • For the actual layout of the chart, use the ‘Sankey diagram’ option available in Tableau’s ‘Network Diagrams’ feature. This can help in efficiently arranging the nodes and flows, especially in more complex diagrams.

6. Customize and Enhance:

   • Apply filters, color schemes, and tooltips to improve the readability and interactivity of the chart.
   • Adjust text labels and orientation to make the chart more understandable and aesthetically pleasing.

Applications of Sankey Charts

Sankey charts find applications across various sectors due to their unique ability to visualize complex flow dynamics:

• Energy Sector: Analyzing energy consumption and production flows between different sources and sinks, such as coal, oil, wind, and solar.
• Economics: Illustrating the distribution of industries’ output, value-added, or material inputs and outputs flows in an economy or by industry.
• Environmental Studies: Visualizing the sources and sinks of pollutants or other environmental flows in ecosystems or industrial processes.
• Data Science: Representing data flow processes within algorithms or data transformation pipelines.

Final Thoughts

Sankey charts are a powerful tool in the data visualization arsenal, offering a unique perspective on how flows between different entities interact and change. Their ability to communicate complex relationships with simplicity and clarity makes them essential in both academic and practical applications. Whether exploring energy flow dynamics, economic interactions, or data processing pathways, the elegance and efficiency of Sankey diagrams continue to be a compelling choice for data analysis and presentation.

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.