Transforming Data into Stories: A Creative Guide to Sankey Charts

In the vast expanse of data visualization, Sankey charts have emerged as a powerful tool for storytelling, enabling readers to grasp complex data flows in a way that is both visually engaging and informative. Unlike traditional bar charts, line graphs, or pie charts, which primarily highlight individual categories or quantities, Sankey charts offer a dynamic way of visualizing the flow and transformation of data. By connecting different datasets through their relationships and flows, Sankey charts provide a comprehensive and interactive experience, allowing viewers to navigate through the data with ease.

Understanding Sankey Charts

Sankey charts, named after Irish Captain Matthew P.M. Sankey, who used them in 1898 to visualize the efficiency of energy use in boilers, are particularly useful for illustrating the proportions or quantities of data flowing between categories or variables. They are a type of flow diagram that displays quantities flowing from one set of categories to another. Each connection in a Sankey chart is scaled for the magnitude of data, making it possible to see not only the direction of flow but also the relative sizes of the datasets.

Components of a Sankey Chart

Sankey charts typically consist of three main components:

Nodes: These represent the starting point or the end point of data flow. They are represented by boxes on the left and right sides of the chart.
Link Lines: These represent the flow of data between nodes. The width or thickness of the link line shows the amount of data being transferred.
Axis: Although Sankey charts are traditionally displayed in a horizontal configuration, they can also be vertical. They serve as references for the data categories, providing context to the flow of data.

Creating Sankey Charts: A Step-by-Step Guide

Identify the Data to Be Visualized: Determine the data that you want to show flow through. This could be anything from energy inputs and outputs to information pathways within a system.
Organize Your Data: Ensure your data is organized in a way that accurately represents the flow you want to visualize. Typically, you start with an origin node and flow through a series of destination nodes, showing how data is being transformed and redistributed.
Determine Your Sankey Chart Layout: Choose the orientation of your Sankey chart. Depending on the space you have available, a horizontal or vertical layout might be more suitable.
Use Software or Programming Language: There are various tools and programming languages you can use to create Sankey charts. Popular choices include Python’s Plotly and Dash, R’s ggalluvial or ggSankey, and interactive tools like Tableau.

Example: Creating a Sankey Chart Using Plotly in Python

“`python
import plotly.graph_objects as go

Data

fig = go.Figure(go.Sankey(
node = dict(
pad=15,
thickness=20,
line = dict(color = “black”, width = 0.5),
label=[‘A’, ‘B1 B2’, ‘C1 C2’, ‘D’, ‘E’],
color=[‘lightblue’, ‘pink’, ‘yellow’, ‘green’, ‘red’]
),
link = dict(
source=[0,1,1,1,2,2,3,4], # indices correspond to columns in “data”
target=[4,0,2,3,2,4,4,3],
value=[8,4,6,5,7,3,2,2] # data values (numerical) in columns
)
)))

Set scene

fig.updatelayout(titletext=”Example Sankey Diagram”, font_size=16)
fig.show()
“`

Applications of Sankey Charts

Sankey charts are versatile and can be applied across various domains, including scientific research, business process mapping, manufacturing efficiency analysis, and ecological studies. Their ability to visually represent data flows makes them exceptionally useful for:

Data Analysis: Helping analysts understand complex data flows and transformations.
Decision Making: Supporting decision-makers in visualizing and analyzing complex systems or processes for improved strategy formulation.
Educational Purposes: Creating engaging infographics that teach students or laypersons about data flow, energy efficiency, or network structures.

Conclusion

Sankey charts are a powerful tool for transforming data into stories that are both visually compelling and informative. Whether you’re a data professional, a scientist, or an educator, integrating Sankey charts into your data visualization repertoire can significantly enhance your ability to communicate complex data in an accessible way. By focusing on storytelling, Sankey charts not only present data but also enable deeper insights into the relationships and patterns within your datasets.

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.