# QuadrantDot (/docs/charts/quadrant-dot)

QuadrantDot answers "where does this item sit in the 2×2 — against the field?". A focal dot is placed by 2-D position, a
hairline cross marks the split (the domain midpoints by default, always overridable but **never hidden**), and the peers
show as tiny muted ghosts. The read is quadrant **membership** first; exact position is the second read — which is why
it lives at glyph scale.

```tsx
<QuadrantDot
  data={{ x: 3, y: 9 }}
  field={[
    { x: 2, y: 8 },
    { x: 8, y: 9 },
    { x: 3, y: 7 },
    { x: 9, y: 2 },
    { x: 7, y: 3 },
    { x: 1, y: 1 },
    { x: 5, y: 6 },
    { x: 6, y: 8 },
    { x: 4, y: 3 },
    { x: 8, y: 5 },
    { x: 2, y: 4 },
    { x: 7, y: 7 },
    { x: 3, y: 2 },
    { x: 6, y: 1 },
  ]}
  xDomain={[0, 10]}
  domain={[0, 10]}
  xLabel="effort"
  yLabel="impact"
  title="Effort vs impact"
  width={96}
  height={96}
/>
```

## Install

```tsx
import { QuadrantDot } from "@microcharts/react/quadrant-dot";

<QuadrantDot data={item} field={backlog} xLabel="effort" yLabel="impact" title="Effort vs impact" />
```

Setup (package + stylesheet): [Quickstart](/docs/quickstart#set-up-with-an-ai-agent) or paste [`/agent-setup.md`](/agent-setup.md) into your agent.


## When to use it

- **Good for** — the classic prioritization 2×2 (one cell per initiative in a table), an effort-vs-impact read in a KPI
  card, any "which quadrant, against the field" decision.
- **Avoid for** — a full scatter plot (MicroScatter) or a single ranked list (MiniBar).


## Variants

```tsx
<QuadrantDot data={item} xLabel="effort" yLabel="impact" />
<QuadrantDot data={item} field={backlog} quadrants={["quick win", "big bet", "skip", "time sink"]} />
```

## Edge cases

```tsx
<QuadrantDot
  data={{ x: 5, y: 5 }}
  field={[{ x: 1, y: 5 }, { x: 8, y: 5 }]}
/>
```

```tsx
<QuadrantDot data={{ x: 5, y: 5 }} field={[{ x: 5, y: 5 }, { x: 1, y: 1 }]} />
```

```tsx
<QuadrantDot data={{ x: NaN, y: 5 }} title="Bad input" />
```

When every field value on one axis equals the focal's, that axis's domain collapses to a point — the split line on that
axis is dropped rather than drawn at an arbitrary spot, while the other axis's split still renders. A peer exactly on
top of the focal is still counted (distance 0) and sorts first in the interactive entry's nearest-first order. A
non-finite focal position draws no marks at all — no cross, no tint, no peers — and carries the "No data." summary, the
same degenerate path an empty series takes elsewhere in the library.


## Why this default

24×24, because the 2×2 is a **position** read, not a scatter plot — you want to know the quadrant at a glance, and the
exact coordinates only when you look closer. The split is data, not decoration: it renders wherever the split truly is
and is always overridable, never invisible. With the axes unlabeled at glyph size, the `title` and `summary` are
load-bearing — skipping them is the one named anti-pattern for this chart, so always pass `xLabel`, `yLabel`, and a
`title`.

## Accessibility

The accessible name states the focal position and the axis-relative quadrant — **"Impact 9, effort 3 — in the
high-impact, low-effort quadrant."** — adding how crowded that quadrant is when a `field` is given, or your own words
via `quadrants={["quick win", …]}`. The interactive entry starts on the focal, then cycles peers nearest-first — each
announced with its coordinates and quadrant.

The interactive entry follows the shared [interaction contract](/docs/accessibility#one-interaction-contract):
arrow keys rove between units on both axes, `Home` and `End` jump to the ends, and a click, tap, `Enter` or
`Space` selects a unit — pinning its readout so it survives blur, until you select it again or press `Escape`.
On touch, a tap pins and a drag scrubs.

## Props

| Prop | Type | Description |
| --- | --- | --- |
| `data` (required) | `{ x; y }` | The focal item's 2-D position. |
| `field` | `{ x; y }[]` | The peer set — omit for a lone glyph. |
| `xDomain` | `[number, number]` | The x-axis range (default: derived from the data); domain stays the y-axis. |
| `domain` | `[number, number]` | The y-axis range (default: derived from the data). |
| `split` | `[number, number]` | The quadrant boundary (default domain midpoints) — never hidden. |
| `quadrants` | `[TL, TR, BL, BR]` | Names in reading order — summaries only, never rendered. |
| `xLabel / yLabel` | `string` | Axis nouns for the summary — pass them, the axes are unlabeled at glyph size. |
| `region` | `boolean` | Faint tint on the focal's quadrant (default true; false for dense grids). |
| `animate` | `boolean` | (interactive) Opt-in entrance motion when the chart mounts client-side — add `import "@microcharts/react/motion"` once. Inert on the server, on hydrated server HTML, and under `prefers-reduced-motion`. |

Plus the shared grammar — `data`, `domain`, `color`, `title`, `summary`, `format` — and the layout props (`width`, `height`, `className`, `style`) that every chart accepts. Interactive entries also share `animate` and `live`, and — wherever a chart has more than one navigable unit — `onActive`, `onSelect`, `selectedIndex` and `defaultSelectedIndex`; and — wherever the chart shows a hover value — `readout`. See [the shared grammar](/docs/quickstart#the-shared-grammar).