Sankey charts are gaining popularity among data analysts, engineers, and decision-makers due to their ability to offer a comprehensive and intuitive understanding of complex systems where energy, material, or information flows. Unlike traditional charts, which typically present discrete information points, Sankey diagrams excel in illustrating the dynamics of flow and transport over an interval or between different processes. Let’s delve into an explanation of Sankey charts to appreciate their significance in various domains.
Originating from engineer and physicist Karl Sankey in the latter part of the 19th century, these visual representations have witnessed a renaissance, especially with the integration of computational tools and graphing libraries into contemporary data analytics. Here’s a closer look into how Sankey charts work and their applications.
**Understanding the Basics**
The Sankey chart features nodes representing processes, activities, or systems, connected by flows that indicate the quantity of energy, material, or information moving in-between them. Each flow is depicted as a horizontal or vertical line with a width proportionally related to the quantity or intensity of flow.
The width of the line represents the magnitude of the flow. A thicker line denotes a more substantial flow, while a thinner line suggests a relatively small quantity or less intense flow. This proportionality ensures that Sankey charts effectively reveal the concentration of flow across the entire chart without the need for color-coding or additional annotations.
**Key Features**
1. **Proportionality**: As mentioned, flow quantity is directly proportional to the line width, making the chart immediate in its ability to communicate information about the relative importance of each flow.
2. **Directionality**: Flows have a specific direction, which indicates the movement or transfer of materials, energy, or information. arrows at the ends of the flows highlight the direction of the transfer.
3. **Cumulative Flow**: In complex Sankey charts, flows can be segmented into sub-flows to illustrate how the total quantity is broken down into its constituent parts.
4. **Net Flows**: Some Sankey charts display net flows, illustrating the balance of flow into and out of a process or system, which can be particularly useful for understanding efficiencies or waste creation.
**Applications**
Sankey charts are versatile and have a diverse range of applications, including:
– **Energy Systems**: Illustrating energy consumption or production across different energy types, such as solar, wind, or nuclear.
– **Process Engineering**: Comparing the efficiencies of different industrial processes and identifying areas for potential optimization.
– **Environmental Studies**: Visualizing emissions, contamination, or resource consumption within environmental impact assessments.
– **Financial Flows**: Depicting the flow of money, investments, or expenditures within companies or across the economy.
**Creating a Sankey Chart**
While traditional Sankey charts were manually drawn with great effort, contemporary applications and libraries have streamlined the process. Tools such as R’s `ggsankey` package, Python’s `matplotlib` with the `sankey` plot type, or online services like Sankey Flow can assist in the creation of Sankey charts based on complex data sets.
In conclusion, the Sankey chart is a powerful and visually compelling tool for data visualization that effectively communicates the flow and transport of materials, energy, or information. Its ability to distill complex systems into a simplified, yet clear representation serves as an invaluable tool for analyzing and optimizing the vast array of processes and systems that underpin our world.
