Sankey charts are powerful data visualization tools that can help us understand complex flow dynamics in fields such as economics, energy, and biology. A Sankey chart is a type of flow diagram that uses arrows or flowing lines to represent the flow of data between different categories or nodes. Unlike basic bar or pie charts, Sankey charts provide a unique way of visualizing the magnitude and direction of data flows, making it easier to identify patterns and trends in large datasets.
In this article, we will explore the creation and applications of Sankey charts as tools for visualizing flow dynamics with ease.
What is a Sankey Chart?
A Sankey chart is a type of flow diagram that uses arrows or flowing lines to depict the distribution and flow of data between different categories or nodes. It is named after the Scottish engineer and physicist Wilson Greatbatch, who introduced the chart type in his work regarding electricity flow. The key characteristic of a Sankey chart is the “Sankey effect” – the width of the lines is proportional to the flow quantity. This visual property allows for easy identification of the largest data flows, which often appear as the widest connections in the chart.
Components of a Sankey Chart
A Sankey chart typically contains the following components:
- Nodes – These represent the categories or entities where the flow starts or ends. Nodes can be displayed either on the sides of the chart or in the center, depending on the chart type.
- Links – These represent the flow between nodes. Links are shown as arrows or flowing lines, where the width of the line corresponds to the magnitude of the flow. The direction of the flow is indicated by the orientation of the line’s arrowhead.
- Flows – These are quantitative measures of the flow between nodes, usually displayed as text near the connections when the chart is large or when needed for clarity.
Types of Sankey Charts
Sankey charts can be categorized based on the layout and connections:
- Horizontal or Vertical Sankey Charts – In these charts, the links and text are displayed either horizontally or vertically along the chart’s axis.
- Flow-Based Sankey Charts – In flow-based Sankey charts, the width of the links is directly proportional to the flow value, and they are positioned along the axis. This type is useful when the flow magnitude is the primary focus.
- Heat Maps – Heat maps show the distribution of flows using color gradients, which can be helpful when analyzing patterns across multiple nodes or categories.
- Tropical Sankey Charts – This type of chart extends the vertical Sankey chart layout to a three-dimensional structure, providing a more immersive and tactile representation of data flows.
Steps to Create a Sankey Chart
Creating a Sankey chart typically involves the following steps:
- Collect Data: Gather the necessary data, including categories, flows between categories, and the magnitude of each flow. Ensure that the categories are discrete and consistent.
- Choose a Tool: Select a tool or software to create the Sankey chart. Popular options include Microsoft Excel, Tableau, Python libraries like Plotly or NetworkX, and web-based tools like FlowCanvas.
- Design the Layout: Decide on the type of Sankey chart (vertical, horizontal, etc.) and the layout where nodes will be placed (center, sides, etc.).
- Input Data: Input the data into the chosen tool, making sure to map each category, flow value, and direction accurately.
- Adjust Settings: Customize the appearance and layout of the chart, such as colors, line widths, and node labels, to enhance readability and visual appeal.
- Review and Refine: Check the chart for any errors or missing data. Adjust the settings as necessary to ensure the chart effectively communicates the flow dynamics.
- Add Interactivity: If using a digital tool, consider adding interactive elements such as tooltips, filters, or clickable nodes to enhance user engagement and information depth.
Applications of Sankey Charts
Sankey charts have a wide range of applications across various industries and fields:
- Economics: Sankey charts can illustrate financial flows, expenditures, and transactions, such as investment portfolio allocations or sectoral contributions to a national economy.
- Energy: They are used to depict energy production, consumption, and distribution, showing how energy is transformed and flows between different energy resources and end-users.
- Supply Chain Management: Sankey charts can help visualize material flows in supply chains, showing the origins of raw materials, intermediate products, and final goods.
- Environmental Science: They are useful for tracking the movement of pollutants, nutrients, or species within ecosystems or across different geographic boundaries.
- Healthcare: Sankey charts can be employed to convey patient flows, treatment pathways, or disease transmission dynamics in healthcare systems.
- Sociology: They can represent social networks, migration patterns, or the flow of goods and services between different communities and economic sectors.
Conclusion
Sankey charts are powerful tools for visualizing flow dynamics across various fields and industries. By leveraging the unique visual properties of Sankey charts, such as proportional line widths and arrows, we can easily identify and understand complex data flows. Creating and applying Sankey charts requires proper data collection, layout design, and software expertise but can lead to insightful visual representations of processes, systems, and networks. Whether used for analytical insights, decision-making, or communication, Sankey charts are an essential tool for anyone looking to explore and communicate the dynamics of data flows.
Embark on your journey of visualizing flow dynamics with ease by utilizing the powerful capabilities of Sankey charts.
SankeyMaster
SankeyMaster is your go-to tool for creating complex Sankey charts . Easily enter data and create Sankey charts that accurately reveal intricate data relationships.
