# IconArray (/docs/charts/icon-array)

IconArray makes a stated rate countable: it prints **3 in 20** beside a grid of twenty units with three of them filled.
`total={20}` and `label="ratio"` are the default pairing because "3 in 20" reads faster for a lay audience than "15%",
and the ratio label plus the fixed grid keep the denominator on the page instead of in the reader's head. Units fill in
contiguous reading order from the top-left: medical-risk-communication research finds scattered fills measurably harder
to count, and counting is the whole point of this chart. There are **no partial-unit fills ever**. A 37% rate is never a
unit drawn 37% full, and a rate too small to fill one unit is flagged rather than faked.

```tsx
<IconArray value={0.15} total={20} title="Adverse events" width={140} height={30} />
```

## Install

```tsx
import { IconArray } from "@microcharts/react/icon-array";

<IconArray value={0.15} total={20} title="Adverse events" />
```

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

## Try it

```tsx
import { IconArray } from "@microcharts/react/icon-array/interactive";

<IconArray
  value={0.15}
/>
```

## When to use it

Use it for risk in a sentence, uptake and adoption rates, and lay-audience probabilities. For a trend use Sparkline; for
a full distribution use QuantileDots.

## Sizing

**1 in 10 framing**

```tsx
<IconArray value={0.1} total={10} />
```

**risk polarity**

```tsx
// fewer is better → filled units read as the risk
<IconArray value={0.15} total={20} positive="down" />
```

## Variants

```tsx
<IconArray value={0.1} total={10} />
<IconArray value={0.15} total={20} positive="down" />
```

```tsx
<IconArray value={0.15} total={20} label="percent" />
<IconArray value={0.6} total={10} shape="round" />
<IconArray value={0.37} total={100} label="none" />
```

## Edge cases

```tsx
<IconArray value={0} total={20} title="No adverse events" />
```

```tsx
// a real but tiny rate rounds to 0 units — flagged, never a fractional fill
<IconArray value={0.01} total={20} title="Rare event" />
```

```tsx
<IconArray value={1} total={20} title="All affected" />
```

A rate of exactly 0 draws every unit hollow. A rate that is real but rounds to 0 whole units (`note: "sub"`) also shows
a hollow grid, and the summary says so rather than standing a fractional unit in for "almost none." `value` is clamped
to `[0, 1]` and non-finite input renders as 0, so a bad upstream number never breaks the grid.

## Four homes

**In a sentence**

```tsx
<p>
  Adverse event rate{" "}
  <span className="mc-inline">
    <IconArray value={0.15} total={20} summary={false} />
  </span>{" "}
  — 3 of 20 patients, 15%.
</p>
```

**In a table cell**

```tsx
<td>
  <IconArray value={0.15} total={20} />
</td>
```

**In a KPI card**

```tsx
<div className="kpi">
  <span className="figure">15%</span>
  <span className="unit">3 of 20</span>
  <IconArray value={0.15} total={20} />
</div>
```

**In a tab header**

```tsx
<button className="tab">
  Cohort A <IconArray value={0.15} total={20} />
</button>
```

## Accessibility

The accessible name gives the count and the rate: **"3 in 20. About 15%."** Degenerate rates are spelled out too ("0 in
20", "20 in 20 — all."). The interactive entry roves the grid in reading order with the arrow keys (2-D, row-major),
announcing each unit's state and the running count: **"Unit 1 of 20 — filled. 3 of 20 filled."**

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, press `Escape`, or
press outside the chart. On touch, a tap pins and a drag scrubs.

## Props

| Prop | Type | Description |
| --- | --- | --- |
| `value` (required) | `number` | The rate, 0–1. |
| `total` | `10 \| 20 \| 100` | Denominator / grid size (default 20). |
| `label` | `"ratio" \| "percent" \| "none"` | "3 in 20" (default) reads better than "15%" for lay audiences. |
| `shape` | `"square" \| "round" \| "dot"` | Shared cell vocabulary (default square). |
| `positive` | `"up" \| "down"` | Polarity — down (fewer is better) flips the fill to the risk tone. |
| `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).