Sankey charts are a powerful tool for visualizing complex flows, such as energy usage, traffic patterns, or information routing. They use arrows or “flows” between nodes to show how data or resources move through a system. This guide explores the creation and applications of Sankey charts, providing insights into how to effectively use this visualization technique.

What are Sankey Charts?

Sankey charts are a type of flow diagram, named after Captain John Langford Sankey, a British civil engineer who used them in the late 19th century to illustrate energy flows in factories. The chart’s primary purpose is to display the quantity or value of flow between connected points in a system. The chart’s thickness is proportional to the magnitude of the flow, providing a clear and concise way to analyze data flows.

Key Elements of a Sankey Chart

A Sankey chart consists of:

1. Nodes: The points in the chart, usually displayed at the top or bottom, representing the start or end of flows.
2. Flows: The paths between nodes, shown as colored arrows or ribbons. Their width indicates the magnitude of the data flow.
3. Labels and Titles: Descriptive text that helps clarify the relationship between the nodes and their flows.

Importance of Sankey Charts

Sankey charts are particularly effective in:

• Identifying Trends: Visualizing the increase or decrease in flow between nodes allows for the easy identification of trends in data usage, production, or consumption.
• Comparison: Comparing different time periods or scenarios can highlight differences or similarities in flows and help pinpoint areas for improvement.
• Education: Providing a clear, visual explanation of complex processes, such as energy generation, can aid in teaching and decision-making.

How to Create Sankey Charts

Creating a Sankey chart involves several steps:

1. Data Analysis

Collect and analyze data on the flows you want to represent. For a flow network, you need:
– Source: The origin of the flow.
– Destination: The ending point of the flow.
– Value: The quantity or magnitude of the flow.

2. Tool Selection

Choose a tool or library that supports Sankey chart creation. Popular options include:

• Vega-Lite: For interactive web charts with JSON syntax.
• Squarify: For desktop applications, offers customizability and detailed chart design.
• R Packages: gplots or flexdashboard for R users.
• Python Libraries: plotly, matplotlib, or networkx for Python developers.

3. Design the Chart

Design your Sankey chart by specifying the nodes, flows, and their relationships:

• Add Nodes: Define the node labels and properties.
• Create Flows: Specify the source, destination, and value for each flow.
• Adjust Aesthetics: Choose colors, labels, and layout to enhance clarity and visual appeal.

4. Implement and Test

Implement the chart using your chosen tool or library. Test the visualization for accuracy, clarity, and usability.

5. Publish and Analyze

Publish the Sankey chart in the desired format (web, desktop application, or printed report) and share it with the intended audience. Encourage feedback to refine future iterations.

Sankey Chart Applications

Energy Systems

A Sankey chart can illustrate the flow of energy within a power grid, showing how different sources (e.g., wind, solar, fossil fuels) supply various demands (heating, lighting, technology).

Traffic Analysis

In urban planning, Sankey diagrams can depict traffic flows within a city, highlighting peak hours or potential congestion spots based on road usage.

Web Analytics

Sankey charts are useful for visualizing the flow of website traffic, showing how visitors navigate different pages and sections of a site, which can inform user experience improvements.

Business Processes

Businesses can use Sankey charts to visualize the flow of materials, people, or services within a company. This insight can improve supply chain management and workflow efficiency.

Sankey charts offer a unique and powerful way to visualize complex flow networks. By carefully designing and implementing these charts, you can gain deeper insights into data flows that would be difficult to discern through numerical analysis alone. Remember to use Sankey charts judiciously, ensuring your audience can easily comprehend the information presented, and consider using interactive elements for web-based applications to enhance the user experience and engagement.

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.