Treemap encodes values as area of nested rectangles for a hierarchy. Ben Shneiderman, University of Maryland, 1991, for disk-space visualization.
In reports, ads and assignments it fits part-to-whole with many leaves and a hierarchy. Skip it when you need precise comparison of similar sizes.
Parts
- Mark — The core mark of Treemap is area of nested rectangles for a hierarchy.
- Scale — The scale must show zero (or a declared break) and units.
- Axis — Axis titles name the variable, not a mood.
- Legend — A legend is weaker than a direct label. Write beside the mark when you can.
- Label — Numbers are optional. If comparison is the job, label the ends only.
- Grid — Keep the grid faint. Data should own the ink.
- Annotation — One annotation sentence. Date the source.
- Frame — A thin frame. Never a 3-D box.
Variants
- Rectangular tree — Variant 1 of Treemap. Same encoding, different layout.
- Shneiderman map — Variant 2 of Treemap. Same encoding, different layout.
- Nested area chart — Variant 3 of Treemap. Same encoding, different layout.
- Treemap 4 — Variant 4 of Treemap. Same encoding, different layout.
Labels
- Axis — On Treemap, make Mark readable.
- Legend — On Treemap, make Scale readable.
- Label — On Treemap, make Axis readable.
- Grid — On Treemap, make Legend readable.
- Annotation — On Treemap, make Label readable.
Treemap: honour area of nested rectangles for a hierarchy, and switch when you need precise comparison of similar sizes.