# Understanding Sankey Charts: A Visual Guide to Optimizing Flows and Processes
Sankey charts are a type of flow diagram named after their inventor, the Scottish engineer and inventor Matthew Henry Phineas Riall Sankey. They are a powerful tool for visualizing the flow of something between different components in a system. This article aims to provide an in-depth understanding of Sankey diagrams, their creation, various types, and how they can be used to optimize processes and flows.
## What are Sankey Charts?
A Sankey chart (or Sankey diagram) is a type of flow diagram where arrows depict quantities and flow magnitude, and the width of the arrows corresponds to the relative importance or volume of the flow. This makes it easier to understand the quantity or importance of the flow between different components in a system.
## Origin and History
Sankey charts are named after Phineas T. Barnum. The concept of the Sankey diagram was introduced in 1898 by an engineer named Matthew Henry Phineas Riall Sankey, who was known for his innovative approach to energy conservation. He used such diagrams to visualize flows of energy within industrial processes, which helped demonstrate the efficiency and losses in thermodynamic systems.
## Types of Sankey Charts
Sankey diagrams can be classified into several types, each tailored to different uses and objectives. Below are the main types and their characteristics:
1. **Basic Sankey Diagram**: This is the most basic form of a Sankey diagram, used to represent flows in any system. It can be used in various sectors such as manufacturing, logistics, electricity distribution, or the internet.
1. **Parallel Sankey Diagram**: In this type of Sankey chart, similar flows that have a similar width and magnitude are grouped together. This helps in simplifying visual complexity, making the diagram more reader-friendly.
1. **Flow Rate Sankey Diagram**: These diagrams use color and size to represent the magnitude of the flows. Typically, flow rates are categorized into different levels or color schemes, such as low, medium, and high.
1. **Interactive Sankey Diagram**: This type of Sankey diagram allows users to filter, drill down, or sort the data to explore different aspects of the flow system. It is commonly used in digital environments (web or mobile) and can be highly informative for complex systems.
## Creating Sankey Charts
### Data Preparation
To create a Sankey chart, you need three main types of data:
1. **Sources**: The starting point or origin of the flow.
2. **Destinations**: The end point or where the flow ends up.
3. **Flows**: The magnitude or volume of the flow from sources to destinations.
### Tools for Creation
Several tools and libraries can be used to create Sankey charts, depending on the platform and requirements:
– **Excel**: A popular tool for creating Sankey diagrams with built-in templates and features.
– **R and Python**: Programming languages with libraries like `sankeyCharts` for R and `networkX` and `pygal` for Python that offer more customization and control.
– **SVG (Scalable Vector Graphics)**: Allows for the creation of complex diagrams with precise control over each element’s appearance.
– **Web-based Tools**: Tools like `D3.js` or `Squarify` provide interactive Sankey charts that are easy to customize and deploy online.
### Design Considerations
When designing a Sankey chart, it’s crucial to consider the following:
– **Flow Orientation**: Choosing the right orientation of the chart can greatly impact its readability. Vertical or horizontal orientation is generally recommended to avoid clutter and make the flows easily understandable.
– **Color Coding**: Use colors to differentiate between different data categories, highlight trends, or show differences in flow sizes.
– **Labeling**: Clearly label the sources, destinations, and flows to provide context and facilitate understanding.
– **Simplicity**: Avoid overcrowding the diagram with too much data. Consider breaking down complex flows into separate diagrams or simplified versions to enhance clarity.
## Applications of Sankey Charts
Sankey diagrams are used across numerous fields, enhancing the way we understand and optimize various systems:
– **Engineering and Energy**: To visualize energy usage, waste flows, and efficiency in industrial processes or environmental models.
– **Logistics and Supply Chain**: To track goods, materials, or information flow within a system, highlighting bottlenecks and facilitating supply chain optimization.
– **Web Analytics**: In digital contexts, to depict click flows, user journeys, or data flow within complex systems, aiding in the identification of potential optimizations or inefficiencies.
– **Economics**: For modeling economic flows, trade, and resource distribution across different sectors or countries, providing insights into economic dynamics and dependencies.
## Conclusion
In conclusion, Sankey charts offer a unique and effective way to visualize and optimize the flow of resources, information, or processes in a system. Whether you’re analyzing energy usage in an industrial facility, tracking data movements in a complex web application, or optimizing logistics in a supply chain, these diagrams provide valuable insights and can facilitate informed decision-making. As these tools continue to evolve, their utility and potential applications in various industries are only set to increase, marking Sankey charts as a cornerstone of data visualization.
