Vega-Lite Rect Heatmap
A rectangular heatmap encoding a numeric variable as cell colour across two categorical axes — the canonical 'matrix view' chart. Vega-Lite's `rect` mark with `x: nominal`, `y: nominal`, and a `color: quantitative` channel produces a continuous-gradient cell grid automatically; l
Template details
- chart
- heatmap
- matrix
- vega
- vega-lite
When to use this template
This visualization excels at revealing patterns, concentrations, and outliers in a quantitative measure when observed across two distinct categorical dimensions. Analysts use it to quickly identify high- or low-value cells, spot trends along rows or columns, and understand the overall distribution of a metric within a grid structure. It's ideal for comparing a metric's value across all pairwise combinations of two categories.
- Data with exactly two categorical dimensions.
- One continuous quantitative measure.
- Categorical dimensions with medium to high cardinality (e.g., 5-50 unique values each).
- When comparing a metric's value across all pairwise combinations of two categories.
- Ideal for time-series data where categories represent time units (e.g., day of week, hour of day).
- When relative differences and absolute values of the metric are equally important.