Sankey charts are an indispensable tool in data visualization, providing a compelling and intuitive way to represent the flow and transformation of resources, energy, or other aspects quantifying dynamic systems. Unlike traditional bar charts or line graphs, Sankey diagrams are uniquely structured to emphasize the magnitude of flow through links, making them ideal for illustrating complex processes where the quantity of flow is a central concern.
Consider a manufacturing process, for example, or a system of energy consumption. With a Sankey chart, each link or arrow visually represents the volume of flow, its width directly proportional to the quantity being portrayed. The beauty of these diagrams lies in their simplicity and effectiveness in conveying information at a glance.
At the core of a Sankey chart, there are inputs, processes, and outputs. The chart begins with sources (input nodes) where resources are introduced into the system, and the flow of resources is depicted as they move through the processes in the system. Once they leave the system, the flow is denoted as output.
### Design Elements and Best Practices
There are several key aspects to consider when crafting a Sankey chart:
1. **Arrow Width**: The width of each arrow should correspond to the absolute quantity flowing. The broader the arrow, the greater the flow.
2. **Link Orientation**: The direction of flow depends on the convention of the chart. Generally, the arrows should indicate the direction of flow, which can be from left to right, as if moving through a process over time, or from top to bottom, as if moving through different systems within a workflow.
3. **Labels**: Sankey charts use labels to denote the type of flow, such as ‘Electrical Energy,’ ‘Water Usage,’ or ‘Carryover Material,’ helping viewers easily understand the significance of each link.
4. **Balances and Intersections**: As resources are not always used completely in producing outputs, a Sankey chart must effectively show unused resources or material losses. The widths of these ‘intersections’ or balancing links will correspond to the amount of flow that is recycled or discarded.
### Use Cases
Sankey charts find use in numerous applications, including:
– **Energy Consumption Analysis**: Demonstrating the efficiency of energy systems in homes, buildings, or industrial facilities.
– **Financial Flows**: Tracking the flow of funds or transactions in a company.
– **Manufacturing Systems**: Illustrating material flow from suppliers through production to customers.
– **Supply Chains**: Visualizing the movement of goods or services from initial suppliers to final consumers.
### The Digital Era
In today’s digital world, specialized software allows for the creation of sophisticated Sankey diagrams with ease. These tools offer users the capability to input data, configure chart properties, and even adjust colors and labeling to best represent the intended message.
Creating an accurate and informative Sankey chart is not merely about the technology used. It’s about distilling complex information flows into a form that’s easily digestible without compromising on detail. When done effectively, these charts can serve as a powerful communication tool that bridges the gap between quantitative data and actionable insights.
