Sankey charts are a popular data visualization tool used to represent flows and transformations within a system. These charts are named after Peter W. Sankey, who first used them in the late 19th century to represent the energy flow in steam engines. Over the years, Sankey charts have evolved and are used across various industries and applications to depict complex flows, such as energy usage, material flows, and data flows.
In this article, we’ll explore the concept of Sankey charts, their creation, and their applications. We’ll also discuss how Sankey charts can help simplify complex data and highlight friction within systems.
Concept and Basics of Sankey Charts
Sankey charts are flow diagrams that use banded arrows to show the magnitude and direction of data flows. The width of the bands is proportional to the quantity or flow of data being represented. The bands can be color-coded to represent different categories or data types. Sankey diagrams are used to depict complex flows, such as flows of energy, materials, people, or money through a system.
Sankey chart components include:

• Sinks – The starting points of the flow, which indicate where data is entering the system.
• Sources – The end points of the flow, which indicate where data is exiting the system.
• Transfers – The intermediate points of the flow, which show how the data is being transformed, transferred, or combined within the system.
• Bands – The banded arrows that represent the magnitude and direction of the data flows between the sources and sinks.

Creating Sankey Charts
Creating a Sankey chart involves the following steps:

1. Collect data – Gather the data you want to represent, including the source and destination nodes, flow magnitude, and flow direction.
2. Define categories – Determine categories or labels for the data flows and define color codes for each category.
3. Determine the layout – Design the layout of the chart and decide on the layout engine to use. There are several charting libraries available that offer different layout algorithms, including orthogonal, hierarchical, and force-directed layouts.
4. Assign weights – Assign weights to the data flows based on the flow magnitude and direction. This is typically done using a formula that considers the flow quantity and distance between nodes.
5. Create the chart – Use a charting library to create the Sankey chart. This involves adding nodes, edges, and bands to the chart and configuring the design and colors.
6. Customize the chart – Customize the chart by adding labels, adjusting colors, and adding interactive elements or tooltips to improve user experience and provide additional information.

Applications of Sankey Charts in Data Visualization
Sankey charts are widely used in various industries, including energy, engineering, finance, and logistics, to represent complex flows. Here are some common applications of Sankey charts:

• Energy Flow – Sankey charts can be used to visualize energy consumption and production within a system, such as a power plant or a building. This helps identify areas of energy inefficiencies and highlights energy-saving opportunities.
• Material Flow – Sankey charts can depict material flows within a manufacturing process or a recycling system. This visualization helps identify waste streams and potential hotspots for sustainable material management.
• Data Flow – Sankey charts can represent data flows within a software or web application, such as user interactions or data processing pipelines. This visualization helps identify bottlenecks and opportunities for optimizing data flow.
• Logistics – Sankey charts can show the routing of goods or materials within a supply chain network or a transportation system. This helps analyze and optimize transportation strategies and identify potential disruptions or bottlenecks.

Benefits of Sankey Charts
Sankey charts have several advantages over other data visualization techniques:

• Intuitive representation – The banded arrow representation makes it easy to understand complex flows and identify the direction and magnitude of data movements.
• Highlighting friction – By visualizing flows and transformations, Sankey charts can reveal friction points within systems, such as bottlenecks or inefficiencies.
• Multi-level perspectives – Sankey diagrams can represent data flows at multiple hierarchical levels, making them suitable for visualizing complex systems with many interconnected components.
• Interactive experiences – Sankey charts can be made interactive using web technologies, allowing users to explore data through tooltips, filters, and other engaging features.

Challenges in Sankey Chart Creation
Despite the benefits, there are some challenges in creating effective Sankey charts:

• Complexity – Creating Sankey charts for highly complex systems can be challenging, as it requires careful planning, data collection, and layout optimization.
• Layout optimization – Determining the optimal layout for a Sankey chart can be a time-consuming process, as it requires balancing bandwidth, color, and label placement to keep the visualization clear and understandable.
• Scalability – Sankey diagrams can become cluttered and unreadable when dealing with a large number of nodes and flows. This requires proper scaling techniques to maintain a clear and effective visualization.
• Accuracy – Ensuring the accuracy of data and labels in Sankey charts is crucial, as misrepresentations or errors can lead to incorrect conclusions.

Conclusion
Sankey charts are a powerful tool for visualizing complex flow data in a variety of contexts. By representing data flows as banded arrows, these diagrams make it easy to understand and analyze the magnitude and direction of data movement within a system. Creating effective Sankey charts requires careful consideration of factors such as data collection, layout optimization, and scalability. With the increasing availability of charting libraries and interactive technologies, Sankey charts are becoming more accessible and useful in data analysis and decision-making.

In summary, Sankey charts offer a unique perspective on system flows, helping organizations optimize processes, reduce waste, and identify potential bottlenecks or inefficiencies. As data complexity continues to grow, the ability to visualize and comprehend these flows becomes even more crucial for informed decision-making and strategic planning.

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.