# `H3Cell`

A cell of Uber's H3 grid of hexagons, as 15 hexadecimal digits: `8928308280fffff`.

Use it to group data by area on a hexagon grid, such as demand by neighbourhood. For a grid of rectangles that shortens by prefix, use [`Geohash`](/docs/types/type-geohash.md).

## Shape

One value, held as text in one set form, with no parts: `8f2830828052d25`.

## Example

```jadpo
H3Cell("8928308280fffff")
```

`H3Cell(raw)` checks the text, and text that isn't one breaks the `format` rule.

`text.parse(raw, as: H3Cell)` reads one from text that comes from outside. Text that isn't one at all fails `malformed`, such as `80f5fffffffffff`, `892830828ffffff` or `8928308287fffff`.

## Good to know

- It checks the bits inside as well as the form, so not every 15 digits pass.
- `==` tells you whether two are the same. `<` and `list.sort_by` don't take it.

## In JSON

A string, in a request, a response or `json.write`:

```json
"8001fffffffffff"
"85283473fffffff"
"8928308280fffff"
```

## Details

<details>
<summary>Text form, storage, how it is shown, and operations</summary>

`H3Cell` is in the group Geospatial, and has been in Jadpo since 0.1.0.

### Text form

`text.from` writes one standard text form, the same form `text.parse` reads back: `8001fffffffffff`, `85283473fffffff` and `8928308280fffff`.

### How it is stored

It is stored in one column named for the field, of type `text`. `8928308280fffff` is stored as `'8928308280fffff'`.

### How it is shown to people

`text.format(value, locale:)` shows it to people in their locale.

With `locale: Locale.en_gb`:

| Value | Shown |
|---|---|
| `8001fffffffffff` | `8001fffffffffff` |
| `85283473fffffff` | `85283473fffffff` |
| `8928308280fffff` | `8928308280fffff` |
| `8f2830828052d25` | `8f2830828052d25` |

### Operations

It also takes `text.parse`, `text.from`, `text.format`, `json.read`, `json.write` and `==`. [How every standard type behaves](/docs/every-standard-type-meets-one-contract.md) says how they work.

</details>