Heatmap

Import

Charts live at their own subpath with their own stylesheet, so an app that never draws one pays nothing for them.

import { Heatmap } from '@the_viveksingh/vivek-ui/charts'
import '@the_viveksingh/vivek-ui/charts.css'

Two categorical axes, intensity for the value

The GitHub-contribution shape, generalised. Intensity is a lightness ramp mixed from the tokens with color-mix, so it holds in dark mode and survives every form of colour blindness - and the real numbers ship in the accessible table either way.

<Heatmap
  title="Errors by service and day"
  showValues
  columns={['Mon', 'Tue', 'Wed', 'Thu', 'Fri']}
  data={[
    { x: 'Mon', y: 'API', value: 12 },
    { x: 'Tue', y: 'API', value: 41 },
    { x: 'Mon', y: 'Web', value: 25 },
    // ...one cell per (column, row) pair; gaps render as empty cells
  ]}
/>

Accessibility

No series is ever encoded by colour alone: each carries a distinct dash pattern and marker shape on top of its colour, so the chart survives greyscale printing and every common form of colour blindness.

The palette is verified rather than asserted. Each theme has its own six colours, because one set cannot clear the 3:1 non-text contrast threshold against both a white and a near-black plot surface. Separation is measured under simulated protanopia, deuteranopia and tritanopia: for one to four series — which is nearly every chart — the closest pair sits at ΔE 17, slightly better than the unmodified Okabe-Ito palette it is derived from. Past four series the dash patterns and marker shapes carry the distinction.

Hostile data

Real series contain gaps and rubbish. Every chart is tested against empty arrays, a single point, all-equal values, negatives crossing zero, NaN, ±Infinity, 1e308 and 1e-320, with an assertion that no rendered SVG attribute ever contains NaN. A bad row degrades the chart; it does not blank your page.

Props

Generated from the package's own type declarations, so this table cannot drift from the code.