Understanding and creating Sankey diagrams can be a powerful tool in visualizing complex flows and transfers. Essentially, Sankey diagrams provide a visual representation of data moving between different entities or processes – they show the flow of energy, materials, money, etc. from one entity to another in different quantities. They are particularly useful when dealing with high volumes of data and multiple pathways, making the information more accessible, transparent, and easier to understand. Here, we’re diving into a comprehensive guide to creating and understanding Sankey diagrams.
## Setting the Foundation
Sankey diagrams use rectangles and arrows to depict the flow of things. Rectangles represent the nodes or entities (sources and sinks), while arrows represent the flow of quantities between these entities. The size of the arrow widths in a Sankey diagram reflects the amount of flow, typically its width proportional to the flow’s value.
### Key Elements
**Sources**: These are the starting points of the flow, usually represented by boxes or nodes without incoming connections.
**Nodes**: These are the points where the flow is transferred. They can be either sources or sinks, and can have incoming and outgoing flows.
**Sinks**: Similarly to sources, sinks represent the end points of a flow, depicted by boxes or nodes without outgoing connections.
### Construction Steps
1. **Data Preparation**: The data you collect needs to define the flow variables (for example, flow, volume, value), sources, and destinations. Ensure datasets like `flow`, `from`, and `to` are in your data source.
2. **Choosing a Tool**: Sankey diagrams can be created in various tools, each with its own set of features and learning curve. Common tools include Microsoft Excel, Tableau, Qlik, and the popular library for Sankey diagrams in Python like PySankey or in R using the ‘networkd3’ package.
3. **Diagram Design**:
a. Set the background of your diagram with colors that distinguish easily.
b. Plot nodes (your entities) on the layout. This involves defining the layout type and its parameters like radial circles or layouts in a specific sequence.
c. Define flows using the flow attributes: widths according to the volume of transaction, color-coding for categories, and possibly different textures or patterns for special flows.
d. Adding labels to nodes and flows enhance understanding; ensure clarity and avoid overcrowding.
4. **Evaluation**:
a. Assess the readability of the diagram. Is the flow clearly visible? Can the viewer easily distinguish between sources and categories?
b. Reflect on the need for annotations or legends. Sometimes, adding detailed legends or explanations by mouseover tooltips can significantly improve usability.
## Crafting an Engaging Sankey Diagram
– **Clarity over Complexity**: Keep your Sankey diagram simple. Too many nodes, sub-flows, or detailed subcategories can make the diagram complicated and hard to interpret.
– **Proportional Representation**: Ensure that the width of the flow lines accurately reflects the volume of the flowing quantity compared to other flows.
– **Focus Area**: If you’re dealing with a large number of flows, consider focusing on the most significant flows rather than every single flow for clarity and impact.
– **Storytelling**: Use the diagram to tell a story. Highlight significant changes, trends, or anomalies. For instance, a sudden decrease could signal an unexpected shift in the process.
## Conclusion
Sankey diagrams are versatile tools that can transform complex data into easily understandable visual representations. Whether you’re analyzing data in sustainability, economics, or logistics, these diagrams can serve as powerful aids in communicating your findings and insights. By following this guide, you’ll be well-equipped to create effective, informative Sankey diagrams that enhance communication and aid in decision-making.
