Flow Visualized: The Sankey Chart Renaissance

In the realm of data visualization, the Sankey chart stands as a venerable but often underappreciated tool. Once a staple of process engineering and energy systems, these flow maps have witnessed a renaissance in the data analytics community. This article delves into the fascinating origins of the Sankey chart, explores the tools and technologies fueling its modern renaissance, and reviews the diverse applications that are reigniting interest in these flow visualizations.

The Evolution of Sankey Diagrams

Pioneered in the mid-19th century by British engineer William Playfair, Sankey diagrams were first designed to illustrate the energy flow in a steam engine. Initially named “hotbox diagrams,” they were adapted by Max Klein in Germany to track the thermal energy in power plants, which is where the name “Sankey diagram” originates from. The charts gained popularity due to their ability to elegantly illustrate the conservation of energy while highlighting inefficiencies and bottlenecks.

Creation of Sankey Diagrams

Creating a Sankey chart is an exercise in graphic design and statistical representation. Each Sankey diagram consists of arrows that depict the flow of energy, water, materials, or money, with the width of the arrows representing the quantity of flow. The key to constructing an accurate Sankey chart lies in the following steps:

1. Data Collection: Gather the necessary quantitative data for each step in the process you wish to visualize.
2. Flow Determination: Identify the flow paths from sources to recipients or from inputs to outputs.
3. Process Mapping: Organize this data into a flow chart format to understand at a high level how flow moves through your system.
4. Arrow Representation: Represent each data stream as an arrow. Use the thickness of these arrows to show the magnitude of the flow.
5. Normalization: In systems with large quantities of flow or many processes, normalization allows for better comparison between streams by scaling the widths of the arrows.
6. Design: Use appropriate graphics, such as lines, shapes, and color coding, to facilitate the communication of the data.
7. Labels and Metrics: Include labels and metrics for clarity, and if the Sankey chart is to be used for comparison purposes, ensure consistency across charts for accurate perception of flow differences.

Modern Tools and Software for Sankey Chart Creation

The resurgence of Sankey diagrams in recent years has been powered by the availability of modern tools and software that make it relatively straightforward to create these flow maps. Among the notable tools are:

• Tableau: This popular data visualization tool includes Sankey chart capabilities that enable users to create diagrams directly from their data sources.
• PySankey: A Python library that offers users the ability to generate Sankey diagrams programmatically.
• Gephi: A free, open-source network analysis and visualization software that allows for intuitive creation of Sankey diagrams.
• Excel: Leveraging some creative methods, Sankey charts can even be constructed manually using Microsoft Excel.

Applications of Sankey Diagrams

Once the preserve of engineering and energy analysis, Sankey diagrams have found diverse applications across various fields:

• Environmental Analysis: Illustrating the flow of greenhouse gas emissions and the efficiency of waste management systems.
• Financial Analysis: Showing the flow of a budget or portfolio returns in organizations.
• Business Process Mapping: Demonstrating the flow of customers, products, or money through a company’s value chain.
• Energy Systems Analysis: Visualizing the efficiency of energy grids or the distribution of energy across buildings.
• Resource Allocation: Illustrating where resources such as water, gas, or workforce are allocated and how they are moved within an organization.

The Sankey Chart Renaissance

The Sankey chart renaissance is a product of better data visualization tools and an ever-growing demand for actionable insights. In an era where the sheer volume and complexity of data can be overwhelming, clear and concise visual representations are paramount. The Sankey chart offers a unique way to simplify complexity, making it a powerful tool for modern analysts and professionals alike.

As we look to the future, it seems that the Sankey chart is more than just a tool; it’s become a lingua franca in the conversation about systems and processes. Its capacity to convey the subtleties of flow in a visually compelling manner ensures its place in the arsenal of any data viz enthusiast.

Whether tracking the flow of information in a digital network or mapping the journey of a molecule in a biochemical process, Sankey diagrams have the ability to transform the way we perceive and understand the world around us—one flow at a time.

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.