Sankey diagrams, often described as the Swiss Army knife of data visualization, have been around for well over a century, yet remain a rare sight in the average data enthusiast’s portfolio. Despite their long-standing existence, the Sankey chart’s unique ability to depict flow and efficiency across a network has earned it the title of a powerful tool for anyone with a need to understand complex data journeys. This guide will equip you with the fundamental knowledge of Sankey charts—what they are, their uses, benefits, and how to create them—so that you can master this elegant method of data representation.
Understanding Sankey Charts
At their core, Sankey diagrams are a type of flow diagram where the width of arrows represents the quantity of the flow. Traditionally, they were used in manufacturing and engineering to illustrate the energy flow in a process or the movement of materials among different elements in an infrastructure. Today, they can represent any form of flow, such as data, commodities, or water.
**Purpose and Structure**
Sankey charts are visual representations of the direction and magnitude of material, energy, or cost flows within a system. Each element within the system forms a connection between sources and destinations, with the width of the link at each point indicating the quantity of the flow.
**Uses and Benefits of Sankey Charts**
1. **Process Analysis**: Sankey diagrams can be used to easily identify inefficiencies in processes by highlighting where flows are too great.
2. **Energy Analysis**: They are particularly effective for energy flow diagrams, illustrating the efficiency of energy use or loss in systems.
3. **Supply Chain Analysis**: Tracking the flow of goods or services in supply chains is easier when utilizing Sankey diagrams.
4. **Resource Allocation**: For government organizations and corporations, Sankey charts can illustrate where resources are allocated and measure their impact on specific areas.
5. **Communication Aid**: Due to their visual clarity, Sankey charts make complex information more palatable and easier to absorb for a wide audience.
**Creating Sankey Charts**
1. **Data Collection**: Before you begin, you need to determine the data source and the nature of the flow you want to represent. Ensure you have accurate flow data, including the start and end points of each flow.
2. **Define the Elements**: Identify the elements that your data will be divided into, for instance, different segments of a supply chain.
3. **Mapping Your Sankey**: Lay out your diagram, starting with your initial sources and ending with your final destinations, mapping your flows as you go.
4. **Use the Correct Software**: There are many tools like Excel, Google Charts, and dedicated software such as Sankey Creator, Sankey Diagrams, and Python libraries (matplotlib, etc.) that can help you create detailed and accurate Sankey charts.
5. **Adjust the Widths**: Customize the widths of the arrows to reflect the amount of flow involved. Ensure that the diagram remains readable and that the flow widths are scaled appropriately.
6. **Labeling and Colors**: It is essential to label each element and use color codes to differentiate different flow types for clarity. Ensure that the color palette is chosen to ensure contrast and clarity.
**Conclusion**
Sankey diagrams are a valuable asset for those seeking to visualize and understand the dynamics of flows in their data. They offer a clear advantage in representing large and complex data sets, providing a simplified and intuitive way to explore and present information. By following this guide, you will be well on your way to utilizing Sankey charts in your own data analysis, visualization, and decision-making processes.
