Sunburst Chart

Overview

A sunburst chart displays hierarchical data in concentric circles, where each ring represents a level in the hierarchy. The inner circle represents the root level, and each successive ring shows the next level of detail. The size of each segment is proportional to its value, making it easy to see the composition and relationships within nested categories. The radial layout efficiently uses space and creates an attractive, intuitive visualization of part-to-whole relationships across multiple levels.

Best used for:

• Visualizing multi-level hierarchical data
• Exploring nested categorical relationships
• Disk space usage and file system visualization
• Organizational structures and breakdown analysis
• Budget or spending allocation across categories
• Product category hierarchies and sales composition

Common Use Cases

Business & Finance

• Budget breakdown by department, project, and expense type
• Revenue composition by region, product line, and SKU
• Sales hierarchy (division → team → rep → product)
• Cost allocation across organizational units
• Market share breakdown by category and subcategory

Data Analysis & Reporting

• Multi-level category composition
• Hierarchical data exploration (drill-down analysis)
• Nested proportions and part-to-whole relationships
• Comparative analysis across hierarchy levels
• Distribution patterns in categorical data

IT & System Analysis

• Disk space usage (folders and subfolders)
• File system visualization
• Database storage breakdown
• Code repository structure and size
• Resource consumption by service and component

Options

Path/Hierarchy

Required - Select hierarchy columns (outer to inner).

Choose multiple columns that define the hierarchical structure. The first column represents the outermost (top-level) category, and each subsequent column represents a nested subcategory. For example: Country → State → City.

Value/Size

Required - Define the size of each segment.

Column

Select the numerical column that determines segment size.

Aggregation Function

Choose how to aggregate values:

Options:

• Sum - Total values (most common)
• Mean - Average value
• Count - Number of records
• Median - Middle value
• Min - Minimum value
• Max - Maximum value

Default: Sum

Settings

Hide Empty Values

Optional - Exclude segments with no data.

When enabled, segments with zero or null values are not displayed.

Hide Labels

Optional - Hide text labels on segments.

Useful when there are many small segments or when you want a cleaner visualization. Hover tooltips still show information.

Show Values

Optional - Display numerical values on segments.

When enabled, shows the actual value (not just label) on each segment.

Understanding Sunburst Components

Ring Structure

• Inner circle (center): Root or top-level category
• Second ring: First subcategory level
• Third ring: Second subcategory level
• Outer rings: Deeper nested levels

Segment Size

• Arc width: Proportional to the value
• Larger segments: Higher values
• Smaller segments: Lower values
• Full circle: Represents 100% of that level

Colors

• Color variations: Distinguish between categories
• Related colors: Often used for parent-child relationships
• Intensity: May indicate depth or value

Interaction

• Click to zoom: Focus on a segment and its children
• Hover: See detailed information
• Breadcrumbs: Show path from root to current focus

Tips for Effective Sunburst Charts

1. Hierarchy Design:

   • Order columns from general to specific (e.g., Continent → Country → City)
   • Limit to 3-5 hierarchy levels for readability
   • Ensure each level has meaningful categories
   • Keep category names short and clear

2. Value Aggregation:

   • Sum: Best for totals (sales, costs, quantities)
   • Count: Good for frequency analysis
   • Mean: Useful for averages across categories
   • Ensure values are positive (negative values not supported)

3. Data Preparation:

   • Remove null or empty hierarchy values
   • Aggregate data at appropriate levels
   • Ensure consistent naming across hierarchy levels
   • Consider grouping small categories into "Other"

4. Visual Clarity:

   • Hide labels if too many small segments
   • Use "Show Values" for exact numbers
   • Leverage click-to-zoom for deep hierarchies
   • Keep color schemes consistent with brand/context

5. Interpretation Guidelines:

   • Start from center and move outward
   • Compare segment sizes at same level
   • Follow paths from root to leaves
   • Look for dominant categories and outliers

6. Performance Considerations:

   • Limit total segments to ~1000 for smooth interaction
   • Consider filtering or grouping for very large datasets
   • Test performance with representative data volumes

Sunburst vs Other Hierarchical Charts

vs Treemap

• Sunburst: Radial layout, shows levels explicitly in rings
• Treemap: Rectangular layout, more space-efficient
• Choose Sunburst: When hierarchy levels are important to visualize
• Choose Treemap: When maximizing space usage is priority

vs Nested Pie Chart

• Sunburst: Modern, interactive, multi-level
• Nested Pie: Traditional, limited to 2-3 levels
• Sunburst advantages: Better for deeper hierarchies, more interactive

vs Tree Diagram

• Sunburst: Compact, proportional sizing, radial
• Tree Diagram: Linear, shows connections clearly, better for branching
• Choose Sunburst: For proportional part-to-whole with many nodes

Example Scenarios

Budget Breakdown

Company Budget → Department → Project → Expense Type

Sales Hierarchy

Total Sales → Region → Product Category → Individual Products

File System Visualization

Root Directory → Folders → Subfolders → Files

Organizational Structure

Company → Division → Department → Team → Employee Count

Troubleshooting

Issue: Too many small segments are cluttered

• Solution: Group minor categories into "Other", limit hierarchy depth, or hide labels and rely on hover tooltips.

Issue: Can't see inner levels

• Solution: Click on segments to zoom into that section. Use interactive features to drill down.

Issue: Colors are confusing or hard to distinguish

• Solution: Limit number of top-level categories, use consistent color scheme, or consider treemap if color distinction is critical.

Issue: Segments are not proportional to values

• Solution: Verify that the value column is numeric and aggregation function is appropriate. Check for negative values (not supported).

Issue: Hierarchy doesn't make sense

• Solution: Verify column order in Path/Hierarchy. First column should be top-level, last column should be most specific.

Issue: Missing segments or incomplete circles

• Solution: Enable "Hide Empty Values" to explicitly exclude nulls, or check for missing data in hierarchy columns.

Issue: Labels are overlapping

• Solution: Enable "Hide Labels" and use hover tooltips instead. Consider reducing number of segments or hierarchy depth.

Issue: Click-to-zoom doesn't work

• Solution: Ensure chart is interactive (not a static image). Check if segments have children to zoom into.