Sankey charts have long been a staple of data visualization for their ability to show complex flows and transfer patterns between different elements. When created and applied effectively, they can transform raw data into a powerful storytelling tool that helps us understand how different variables are connected and related over time.
In this article, we will take a closer look at how to create Sankey charts, the different types available, and some of their potential applications. We’ll also examine some use cases where Sankey charts have proven to be particularly effective.

Creating a Sankey Chart

When creating a Sankey chart, the first step is to gather and organize your data. This typically involves identifying the variables of interest, such as source, target, and flow values. The data should be structured in a way that aligns with the chart’s requirements and typically includes columns for the source node (where the flow originates), the target node (where the flow is directed), and the amount of flow or volume between the two nodes. You may need to calculate these amounts based on underlying data or combine data from multiple sources.
Once your data is prepared, selecting a visualization tool is the next step. Many popular data visualization libraries and charting frameworks offer Sankey chart capabilities, including Gephi, Tableau, and Power BI. You can choose a tool based on your familiarity with the platform, the sophistication of the charts it provides, and your team’s expertise. Alternatively, you can create Sankey diagrams manually using graphic design software like Adobe Illustrator or InDesign, or utilize specific Sankey chart libraries, such as the Sankey.js library for web-based apps.
To create the chart, you’ll typically follow these basic steps:

1. Choose your layout direction (horizontal or vertical) and starting orientation.
2. Sort the elements (nodes and flows) to improve readability.
3. Adjust the chart’s appearance, such as colors, line widths, and labels.
4. Add tooltips for hover effects and details on specific flows.

Types of Sankey Charts

Different variations of Sankey charts exist, each tailored to specific applications and needs. Some of the most common types include:

1. Simple Sankey Chart – This is the basic form, showing two or more elements connected by lines.
2. Tree-like Sankey Chart – Used to display hierarchical structures, where multiple branches converge at a single node, resembling a tree.
3. Stacked Sankey Chart – Displays several flows originating from a single node, with a stacked layout to show the contribution of each flow to the total.
4. Grouped Sankey Chart – Used to compare multiple Sankey diagrams within a single chart, making it easier to assess similarities and differences between categories or datasets.
5. Composite Sankey Chart – Created by combining Sankey diagrams in a way that shows flows connecting different charts, often integrated into more complex visualizations to display interconnected systems.

Applications of Sankey Charts

Sankey charts are widely used across various fields for their ability to illustrate flow-based data in a visually engaging way. Some key applications include:

1. Resource Allocation – Show where resources flow between different departments, countries, or industries within a company or globally.
2. Energy Flows – Illustrate how energy is consumed, transferred, and lost across different sectors, such as electricity distribution or renewable energy sources.
3. Economic Flows – Visualize trade relationships, employment dynamics, or income distribution between countries, sectors, or regions.
4. Biological Flows – Display biochemical pathways, ecological interactions, or species interactions within ecosystems.
5. Network Analysis – Analyze connections and flows in networks, like internet traffic, public transportation routes, or social media interactions.
6. Environmental Flows – Track pollution, water usage, or climate change effects across different geographic areas or sectors.

Sankey charts are particularly effective in storytelling because they can convey complex transfer patterns, correlations, and dependencies in a visually intuitive manner. Whether it’s explaining how a company utilizes resources, how a country’s economy is interconnected, or an ecosystem’s various components, Sankey charts can provide valuable insights and facilitate data-driven decision-making.

By leveraging the power of Sankey charts in your data visualization toolkit, you can bring your data to life, making it accessible and compelling to various audiences. To create impactful Sankey charts, consider your data’s story and carefully choose the chart type that best matches your narrative. Experiment with different layouts, colors, and visual elements to enhance readability and engage your viewers. With these steps in mind, you’re well-equipped to unleash the power of Sankey charts and turn complex flow data into easily digestible insights.

SankeyMaster

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