Demystifying Sankey Charts: Understanding Flow Visualization and Its Applications in Energy, Logistics, and Beyond
Sankey charts, a visually appealing and informative graphical representation technique, offer a unique way of visualizing flow networks. These charts are widely utilized in diverse fields, such as energy, logistics, and various scientific studies, to help comprehend complex systems and their interconnections. This article will explore the fundamental aspects of Sankey charts, their construction, and provide real-world applications which showcase their utility.
### What Are Sankey Charts?
Sankey charts originate from the work of the Scottish engineer, Matthew VISIT (1744–1822). They are named after him, though they were initially developed by his cousin, John Frederick William Sankey, as a means to illustrate the energy consumption and wastage in industrial boilers. The main feature of a Sankey diagram is its “flow” concept, where the width of the arrows or links is proportional to the flow quantity, making it an excellent tool for representing data that involves significant quantities.
### Anatomy of a Sankey Chart
A typical Sankey chart consists of two main elements: sources and sinks, and flows. Sources indicate where the substance (or data) begins its journey, while sinks represent where it ends. Nodes, which can be nodes of equal importance or a hierarchical structure of categories, connect these sources and sinks. Links or arrows are drawn between these nodes, with the width of the arrows representing the magnitude of the flow – the more substantial the quantity of the data or substance, the wider the link appears.
### Construction of Sankey Charts
Creating a Sankey chart involves several steps that include data preparation, calculation of the flow values, creating links with the corresponding widths, and arranging the nodes on the chart. This process can be manual, but the use of specialized software such as Tableau, Microsoft Power BI, and various programming libraries (e.g., Plotly, bokeh for Python) significantly simplifies the creation of sophisticated Sankey diagrams.
### Applications in Different Fields
#### Energy
In the energy sector, Sankey diagrams are invaluable for illustrating the movement of energy through various systems – from production to distribution to consumption. This visualization aids in identifying inefficiencies, areas with potential for energy savings, and patterns in energy use across different regions and sectors.
#### Logistics
In logistics and transportation, Sankey maps can show the flow of goods and materials between suppliers, manufacturers, distribution centers, retailers, and consumers. By representing these flow networks, businesses can optimize supply chain management, identify bottlenecks, and plan for more efficient distribution strategies.
#### Environment and Waste Management
For environmental studies and waste management purposes, Sankey diagrams can depict the flow and transformation of materials in ecosystems or recycling processes. This can highlight areas where resources are lost or recycled, pointing to potential improvements and sustainability measures.
#### Health and Social Sciences
In the social and health sciences, Sankey charts are used to visualize patient flow in hospitals, treatment pathways in health interventions, or the movement of individuals between social groups. These visualizations are crucial in understanding public health trends, population migration patterns, and the impact of various policies or interventions.
### Conclusion
Sankey charts, with their ability to provide a clear, intuitive understanding of flow patterns and complex systems, have become an indispensable tool across various disciplines. Whether it’s streamlining logistics for cost savings in the business world or elucidating intricate relationships in environmental and medical studies, Sankey diagrams offer a powerful method of visualization. Their adaptability and wide-ranging applications continue to make them an important component in decision-making processes and analysis of flow dynamics in numerous industries.
