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A space-filling visualization of hierarchical data using nested rectangles sized by value.
DESCRIPTION
A treemap represents hierarchical structures by recursively subdividing rectangles, where area encodes a quantitative metric. Squarified algorithms improve aspect ratios for readability. Color can encode categories, secondary metrics, or change over time. Treemaps excel at showing composition, dominance, and outliers within large hierarchies. Drill-down and zoom interactions enhance exploration.
ALTERNATIVE DEFINITIONS
Wikipedia
A treemap is a method for displaying hierarchical data using nested rectangles.
Concise focus on hierarchy and nested rectangles.
Tableau
A treemap is a chart type that displays hierarchical data using nested rectangles, where the size of each rectangle is proportional to its value.
Adds explicit note on proportional sizing to value.
Data to Viz
A treemap displays hierarchical data as a set of nested rectangles. Each group is represented by a rectangle, which area is proportional to its value.
Explains grouping and area proportionality in simple terms.
RELATED TERMS
Hierarchical Data D3.js Zoomable Treemap Squarified Treemap Partition Layout Tree Diagram Heatmap Drill-down
COMPETING TERMS
Sunburst Chart Icicle Chart
KNOWLEDGE AREAS
Data Visualization Data Science Platform & Tooling
TARGET AUDIENCE
BI Specialist Data Analyst Data Scientist UI-UX Designer Product Owner
EXTERNAL SOURCES
- Wikipedia - Treemapping
- Data to Viz - Guidance and pitfalls of treemaps
- D3.js - Interactive treemap examples
- Vega - Treemap specification example
TOP QUESTIONS
When should I use a Treemap?
Use treemaps to show hierarchical composition and compare relative sizes within and across groups when space is limited.
Category: Best Practices
How is size encoded in a Treemap?
Rectangle area encodes the quantitative value, with hierarchical nesting representing levels in the tree.
Category: Concepts
What algorithm improves Treemap readability?
Squarified treemaps aim for aspect ratios closer to squares, improving visual comparison.
Category: Technique
What are common mistakes with Treemaps?
Using too many tiny rectangles and inconsistent color encoding. Aggregate small items and design a clear legend.
Category: Mistakes
How do Treemaps compare to Sunburst charts?
Both show hierarchies, but treemaps are space-efficient and emphasize area; sunbursts highlight levels with radial layout.
Category: Comparison
Can Treemaps show multiple metrics?
Yes, use color for a secondary metric, and tooltips or labels for details. Avoid overloading encodings.
Category: Design
How do I handle labels in small rectangles?
Use roll-ups, truncation, tooltips, or interactive zoom to reveal detail on demand.
Category: Design
Are Treemaps good for time series?
They are not ideal for trends. Consider small multiples or animation carefully to show change.
Category: Guidance
What data is required for a Treemap?
You need hierarchical groupings and a quantitative value per node, usually with a parent-child relationship.
Category: Data