Creating an insightful Sankey chart: A stepwise guide
Sankey charts, a type of flow diagram, are utilized to visually represent material or energy transfers between multiple points or areas. They serve as an effective tool in illustrating the quantity of data flowing, the pathways by which information moves, and the amount of material conserved.
Deciphering Sankey Diagrams and Their Dynamics
Sankey charts visually capture the flow and transformation of quantities, using rectangular nodes for sources, sinks, and storage, and connecting them with arrows whose widths may vary to indicate specific quantities. These unique diagrams are often used in diverse fields such as environmental science, engineering, economics, and business analytics.
Steps to Create an Informative Sankey Chart
1. **Data Collection**
Analyze the data you want to visualize. This usually includes sources, destinations, and the quantity being transferred. It’s vital to clearly understand how quantity flows from one point to another as this forms the basis of your Sankey chart.
2. **Data Preparation**
Organize your data in a suitable format. The most common is an ‘edges’ DataFrame or table that includes fields for the source, destination, and value of flow, while a ‘nodes’ DataFrame or table provides information about each node – its name, role (if it’s a source or sink), and unique identifier.
3. **Choosing the Right Tool**
While several software applications and online tools exist for creating Sankey diagrams, let’s consider popular packages: matplotlib, networkx, and the more specialized libraries like pyvis, and Sankey from the py-graphviz package.
4. **Design Setup**
Adjust your design setup based on the tool you’ve chosen. This includes setting up the dimensions of your chart, color schemes, and adding titles or labels.
5. **Plotting the Chart**
Use your chosen library to define nodes and edges. For each edge, provide information about the source, destination, flow value, and sometimes the color. This step creates a link between nodes where you assign the direction and size of the flow, based on the data value.
6. **Customizing Appearance**
Fine-tune your chart’s appearance to ensure clarity. This involves adjusting arrow widths to reflect flow values, adding texts, colors, and hover effects, and refining edge labels.
7. **Validation**
Review your Sankey chart for errors or inconsistencies. Ensure that the total flow in is equal to the total flow out at each node, a basic tenet for the correct usage of Sankey diagrams.
8. **Final Touches and Outputs**
If necessary, make adjustments as needed to the flow values or visual styles before finalizing your chart. Export the chart in a suitable file format (PNG, PDF, SVG, etc.) for sharing or publication.
Creating an Informative Sankey Chart
Crafting an effective Sankey chart requires balance in information presentation and design aesthetics. By following a clear, structured approach like the one outlined above, you can ensure that your Sankey chart effectively communicates the flow dynamics of the data you’re presenting – enhancing understanding and engagement for your audience.
Remember, the key is to translate complex data relationships into a visually intuitive form so that even at a glance, trends, patterns, and notable data points stand out. This not only makes sophisticated data more accessibility but also aids in quicker decision-making based on the insights derived from these diagrams.
