Part of a whole

Voronoi treemap

Represents hierarchical composition with recursively partitioned polygons sized by value.

Chart
Hierarchy
Composition

What it answers

How is size distributed within a hierarchy?

Shape: Nested irregular polygons
What it shows: Large branches and nested shares.

Example

The question

Which product categories and lines bring in the most revenue?

Revenue by category and product line, 2025 (Voronoi treemap)

A circle split into irregular cells: thick borders mark categories, inner cells product lines, area in proportion to revenue. Computing 33 (laptops 18, monitors 9, tablets 6); mobile 21 (phones 14, cases 4, chargers 3); audio 15 (headphones 8, speakers 7); accessories 5 (cables 3, bags 2). EUR million.

Illustrative data. It belongs to no company.

When to use it

Use it when

Exploratory hierarchical composition with a distinctive layout.

Avoid it when

Precise comparisons or unfamiliar audiences.

How to read it

Follow polygon containment and compare areas using labels.

The data you need

Layout: Parent-child table
Fields: NodeID: text; ParentID: text/blank; Label: text; Value: number when size is encoded
One row is: One node in a parent-child hierarchy. What is the grain?
Rules: Node IDs must be unique. Parents must exist. Reject cycles. Define leaf-only versus inclusive parent values.
Optional: Alternative: Level1,Level2...,Value. Tree diagrams can omit Value.
Preparation: Validate unique node IDs, parent links, roots and absence of cycles. For size-encoded hierarchies, state whether totals are leaf-only or inclusive.
Units: Tree levels and branch position are structural. Size-encoded components use a named value unit; parent shares divide by the chosen parent total.

A parent-child table: each row names its parent, which together form the tree.

Worked example

Root 100 with A60, B40 is partitioned into polygons of 60% and 40% area. Further subdivision stays inside its parent.

NodeID	ParentID	Label	Value
root		All	100
a	root	A	60
b	root	B	40

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