Part of a whole

Icicle chart

Shows hierarchy levels as rectangular bands with child widths partitioning their parents.

Chart
Hierarchy
Composition

What it answers

How do hierarchical parts relate across levels?

Shape: Stacked hierarchical rectangles
What it shows: Branch structure and proportional subdivisions.

Example

The question

How does revenue break down from category to product line?

Revenue by category and product line, EUR million (icicle chart)

Rows from top: all revenue, categories, product lines; width shows 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

Hierarchy with labels that benefit from rectangular layout.

Avoid it when

Very deep trees in limited height or negative area values.

How to read it

Read the root band, then descend into child rectangles.

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 divides into A60 and B40. The next level splits A into 20 and 40 while retaining their widths within A.

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

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