Unraveling Complex Flows with Sankey Diagrams: A Comprehensive Guide to Visualization and Data Representation
Sankey diagrams are a visual representation technique used to represent the transfer of quantity, from one point to another, which might be energy, material, money or any other quantity with a defined flow. They were invented by Scottish statistician, Matthew Henry Phineas Riall “Phineas” Sankey, and later given its name due to his influence in the development of these diagrams. Essentially, Sankey diagrams are a type of flow diagram that illustrates the quantifiable flow between entities—whether that be human resources, traffic flows, material processing, or financial transactions. This article dives into the world of Sankey diagrams, exploring their benefits, how to create them, and their applications across diverse industries.
### Benefits of Sankey Diagrams
Sankey diagrams offer several advantages for data visualization and analysis, making them increasingly popular in various sectors:
#### Visual Clarity and Intuition
Sankey diagrams provide a clear visual depiction of the flow and distribution of quantities, enabling quick comprehension of data patterns and trends. They are particularly effective in showing the volume of flows, as thicker arrows indicate higher quantities, and are thus ideal for conveying complex data relationships at a glance.
#### Data Interpretation
These diagrams make it easy to identify and compare the flow of quantities between different sources and destinations, revealing patterns that may not be evident in tabular or simple line graphs. This aids in spotting major contributors, recipients, and where significant changes occur, enhancing the interpretability of large datasets.
#### Storytelling with Numbers
Sankey diagrams are a powerful storytelling tool, allowing data analysts and scientists to weave narratives about processes with clear visual illustrations. This capability is invaluable when presenting intricate data to stakeholders who may not have a technical background, helping to communicate the significance of data trends effectively.
### Creating Sankey Diagrams
#### Data Preparation
Before creating a Sankey diagram, it’s crucial to prepare data meticulously. The data will consist of a source node, a sink node, and a set of edges representing the intermediate nodes. Data often includes quantities associated with each flow, but if not, flows are typically normalized over time or with respect to a common baseline for comparison.
#### Using Spreadsheet Software or Specialized Tools
Creating Sankey diagrams requires specific tools or software as they are graphic elements best handled by visual analytics platforms. Popular software options include:
– Microsoft Excel, enhanced with a plugin or add-in such as Sankey Diagram Add-In or AladinSankey.
– Power BI, offering comprehensive Sankey diagram creation capabilities through its interface.
– Tableau, integrating with third-party tools specifically designed to handle Sankey diagram creation.
– R, combined with packages like diagram and gridExtra, for those preferring a more customizable and programming-driven approach.
– Python, with libraries such as pandas for data manipulation and networkx for the network creation, often coupled with matplotlib or seaborn for visualization.
#### Design and Customization
When creating your diagram, focus on simplicity and clarity:
– Use a single color for the starting node.
– Gradually change color through the diagram to distinguish different types of flows.
– Maintain consistent line widths while adjusting the opacity to enhance visibility.
– Utilize tooltips or labels for hover information to provide additional data context without cluttering the diagram.
### Applications Across Industries
#### Energy and Environmental Science
In the energy sector, Sankey diagrams can illustrate the sources, storage, and consumption of energy, indicating efficiencies, waste, and potential areas for improvement.
#### Logistics and Supply Chain Management
Sankey diagrams provide clarity on material or product flows through different stages of a supply chain, highlighting bottlenecks, optimization opportunities, and potential disruptions.
#### Economic Analysis
In economics, they can visualize trade flows, economic sectors’ interdependencies, or the distribution of wealth across regions, aiding in policy-making and market analysis.
#### Social Sciences
Social scientists use Sankey diagrams to chart the flow of social connections, influence, or the movement of ideas across different communities and populations.
#### Urban Planning and Architecture
In urban settings, they can depict flow dynamics such as pedestrian traffic, vehicular movement, and natural resource usage, informing efficient planning and urban design.
Sankey diagrams have found wide-ranging applications due to their versatility. By providing clear visualizations of flow dynamics, they empower decision-makers across many fields to perceive and understand complex data relationships effectively. With the advanced tools and techniques discussed here, businesses, government agencies, researchers, and urban planners can leverage Sankey diagrams to uncover insights that are otherwise hidden within the numbers, ultimately leading to more informed decisions, optimized processes, and better societal outcomes.
