🔀Sankey Diagram

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Also known as: Sankey Chart

A flow visualization where link thickness encodes the magnitude of flow between categories or stages.

DESCRIPTION

A Sankey diagram visualizes how quantities move between categories, with link widths proportional to flow magnitude. It is effective for energy balances, user journeys, cost allocations, and process transitions. Nodes represent categories or stages; edges represent flows. The layout emphasizes conservation and distribution patterns, highlighting major contributors and losses. Designers should avoid excessive node counts to maintain readability and consider ordering to minimize crossings. Interactive implementations often support tooltips and filtering for exploration. Sankey diagrams are available in BI tools and libraries such as Plotly, D3, and Google Charts.

ALTERNATIVE DEFINITIONS

Wikipedia

A Sankey diagram is a specific type of flow diagram, in which the width of the arrows is proportional to the flow rate.

Concise definition focused on proportional arrow widths.

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Data Viz Catalogue

A Sankey Diagram is a flow diagram where the width of the arrows is proportional to the flow quantity.

Describes usage patterns and visual characteristics for practitioners.

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Google Developers

A Sankey diagram is a visualization used to depict a flow from one set of values to another.

Highlights mapping flows between sets for interactive charts.

Source

RELATED TERMS

Flow Map Parallel Sets Treemap Network Graph Sunburst Chart Process Mining Data Flow Diagram

COMPETING TERMS

Alluvial Diagram Chord Diagram

KNOWLEDGE AREAS

Data Visualization Data Science Data Warehousing & BI

TARGET AUDIENCE

BI Specialist Data Analyst Data Scientist

EXTERNAL SOURCES

• Wikipedia - Sankey diagram
• Google Developers - Official Sankey chart documentation
• Plotly - Python Sankey examples
• D3 - D3 Sankey implementation example

TOP QUESTIONS

When should I use a Sankey Diagram?

Use it to show how quantities split and merge across categories or stages, such as energy balances, user journeys, or cost allocations.

Category: Application

What are drawbacks of Sankey Diagrams?

They can become cluttered with many nodes and crossings. Poor ordering reduces interpretability, and exact comparisons can be hard without interactivity.

Category: Risks

How do I improve readability of a Sankey Diagram?

Reduce categories, order nodes to minimize crossings, group small flows, and use consistent color encoding for categories or sources.

Category: BestPractice

How is a Sankey Diagram different from a Chord Diagram?

Sankey emphasizes directional flow magnitudes between stages; chord diagrams show interconnections in a circular layout without explicit stage ordering.

Category: Comparison

What data structure is required for a Sankey Diagram?

Typically a node list and a link list with source, target, and value fields, optionally with group or color attributes.

Category: Requirements

Is a Sankey Diagram suitable for time series?

Only if stages represent time buckets or states; otherwise consider alluvial diagrams or flow maps for temporal dynamics.

Category: Opinion

Can I create a Sankey Diagram in BI tools?

Yes. Many tools (e.g., Power BI via custom visuals, Plotly, Google Charts) support Sankey visuals and templates.

Category: HowTo

What is a typical use case for a Sankey Diagram?

Visualizing user drop-off across funnel stages, highlighting where major loss occurs and which paths dominate conversions.

Category: Example

What is currently a hot topic around Sankey Diagrams?

Interactive and animated Sankey charts for clickstream analysis and integration with process mining are popular.

Category: Topic