# SegmentedBar (/docs/charts/segmented-bar)

SegmentedBar answers "what is this made of, and in what proportions?". Segments always sum to the full bar; past
`maxSegments` the tail rolls into a labeled "Other" — nothing is silently dropped. A flat bar beats a donut of the same
data at every size we ship.

```tsx
<SegmentedBar
  data={[
    { label: "Chrome", value: 620 },
    { label: "Safari", value: 240 },
    { label: "Firefox", value: 90 },
    { label: "Edge", value: 30 },
    { label: "Arc", value: 20 },
  ]}
  title="Browser share"
  width={220}
  height={20}
/>
```

## Install

```tsx
import { SegmentedBar } from "@microcharts/react/segmented-bar";

<SegmentedBar data={mix} title="Browser share" />
```

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** — traffic mix per table row, composition in KPI cards.
- **Avoid for** — precise cross-row comparison (MiniBar) or negative parts (Waterfall).


## Variants

```tsx
// label="percent" is the default — segment shares when they fit.
<SegmentedBar
  data={[
    { label: "Chrome", value: 620 },
    { label: "Safari", value: 240 },
    { label: "Firefox", value: 140 },
  ]}
/>
```

```tsx
<SegmentedBar
  data={[
    { label: "Firefox", value: 90 },
    { label: "Chrome", value: 620 },
    { label: "Safari", value: 240 },
  ]}
  order="desc"
/>
```

```tsx
<SegmentedBar
  data={[
    { label: "Chrome", value: 12400 },
    { label: "Safari", value: 6200 },
  ]}
  label="value"
  locale="de-DE"
/>
```

`label="value"` follows `format`/`locale` — 12400 reads "12.400" under `de-DE` rather than the English "12,400".
`label="percent"` is unaffected: the largest-remainder shares are always plain integers, never locale-formatted, because
a percent point is the same everywhere.

## Edge cases

```tsx
<SegmentedBar data={[
  { label: "Chrome", value: 620 },
  { label: "Safari", value: 240 },
  { label: "Firefox", value: 90 },
  { label: "Edge", value: 30 },
  { label: "Arc", value: 12 },
  { label: "Brave", value: 8 },
]} label="percent" />
```

```tsx
<SegmentedBar data={[{ label: "Chrome", value: 1 }]} />
```

Past `maxSegments` (default 5) the smallest categories merge into a labeled "Other" — nothing is dropped, only rolled
up, and the interactive entry announces its member count. A single category still renders as one full-width, 100%
segment rather than a special-cased bare bar. Negative values can't exist in a part-to-whole, so they're excluded from
the bar entirely (not clamped to zero) and the component logs a dev warning steering toward Waterfall.


## Why this default

Data order is the default — inherent sequences (funnel-like stages, weekday mixes) carry meaning that ranking destroys.
Summary percents use largest-remainder rounding so they always sum to exactly 100; negative values are excluded with a
dev warning (a part-to-whole cannot contain negative parts — use Waterfall).

## Accessibility

The accessible name is the full composition — **"Chrome 62%, Safari 24%, Firefox 9%, Edge 3%, Other 2%."** The
interactive entry roves segments; the Other segment announces its member count (**"Other: 2%, 2 categories."**).

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) | `{ label; value }[]` | Parts of the whole. |
| `maxSegments` | `number` | Rollup threshold — the tail becomes a labeled Other. |
| `order` | `"data" \| "desc"` | Preserve inherent sequences or rank the composition. |
| `label` | `"none" \| "percent" \| "value"` | Centered per segment (deterministic drop-out; default percent). |
| `colors` | `string[]` | Per-segment colours, cycled; overrides --mc-cat-N. Other stays neutral. |
| `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).