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correlation family
heatmap
Grid where colour intensity encodes value.
Each cell's colour shows a quantity. Reads at a glance for "where are the highs". Strong for correlation matrices, calendar heatmaps, geo-by-time tables.
When to use
Two-dimensional grid where the eye should scan for hot/cold spots.
When NOT to use
Cells contain text labels rather than colour-encoded values (that is matrix-categorical-coded).
Rhetorical roles
- correlate
- distribute
Variants & related
Required primitives
- has_legend (colour scale)
- has_axis_titles
Optional primitives
- has_data_labels
- has_source_note
Common anti-patterns
- rainbow-palette
- missing-label
Disambiguation rules
- Equal-width, equal-height grid of cells coloured by value.
- If column widths VARY proportionally, it is marimekko.
- If cells contain category names rather than colour-encoded values, it is matrix-categorical-coded.