# `Ratio`

One number to another as written, `16:9`: `16:9` and `32:18` are two values.

[Maths and data](types.md#maths-and-data); not ordered; since Jadpo 0.1.0.

## Make one

Build one from its fields, `Ratio { numerator: ...  denominator: ... }`.

`text.parse(raw, as: Ratio)` reads one from its text; text that isn't one at all fails `malformed`, such as `16/9`, `16 : 9` or `16:`.

## Fields

| Field | Type |
|---|---|
| `numerator` | `Decimal` |
| `denominator` | `Decimal` |

## Text, JSON and storage

`text.from` writes its canonical text, the one form `text.parse` reads back. JSON sends its canonical text as a string.

| Text | JSON |
|---|---|
| `16:9` | `"16:9"` |
| `1.85:1` | `"1.85:1"` |
| `4.0:3.0` | `"4.0:3.0"` |

It is stored in 2 columns, each named for the field, `_` and its suffix. This is `1.85:1`:

| Column | Type | Holds |
|---|---|---|
| `<field>_numerator` | `numeric` | `1.85` |
| `<field>_denominator` | `numeric` | `1` |

## Shown to people

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

With `locale: Locale.en_gb`:

| Value | Shown |
|---|---|
| `16:9` | `16:9` |
| `1.85:1` | `1.85:1` |
| `4.0:3.0` | `4.0:3.0` |

## Operations

It has the contract's own operations: `text.parse`, `text.from`, `text.format`, `json.read`, `json.write` and `==`. It isn't ordered, so `<` and sorting don't take it. [Every standard type meets one contract](../topics/every-standard-type-meets-one-contract.md) says how they work.