Circle

On this page

Shape
Example
Good to know
In JSON
Details

A centre and a distance around it.

Use it for "within 5 km of here", such as a delivery radius. For a drawn area, use Polygon.

Shape

Field	Type	Required?
`centre`	`Point`	Yes
`radius`	`Length`	Yes

Example

example

Circle {    centre: Point { latitude: 51.5072 longitude: -0.1276 altitude: none }    radius: 1km}

Good to know

The radius can't be below zero, and it is measured on the ground.
== tells you whether two are the same. < and list.sort_by don't take it, so sort by one of its parts instead.

In JSON

An object of its parts, in a request, a response or json.write:

json

{"centre":{"type":"Point","coordinates":[-0.1276,51.5072]},"radius":{"value":"1000","unit":"metre"}}{"centre":{"type":"Point","coordinates":[0,0]},"radius":{"value":"0","unit":"metre"}}

Details

Text form, storage, how it is shown, and operations

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

Text form

It has no single text form, so text.from and text.parse don't take it.

How it is stored

It is stored in 2 columns, each named for the field, _ and its suffix. This is {"centre":{"type":"Point","coordinates":[0,0]},"radius":{"value":"0","unit":"metre"}}:

Column	Type	Holds
`<field>_centre`	`geography`	`'SRID=4326;POINT (0 0)'::geography`
`<field>_radius`	`numeric(38, 6)`	`0`

How it is shown to people

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

With locale: Locale.en_gb:

Value	Shown
`{"centre":{"type":"Point","coordinates":[-0.1276,51.5072]},"radius":{"value":"1000","unit":"metre"}}`	`1,000 m around 51.5072° N, 0.1276° W`
`{"centre":{"type":"Point","coordinates":[0,0]},"radius":{"value":"0","unit":"metre"}}`	`0 m around 0°, 0°`

Operations

geo.contains(a: T, b: U) -> Bool: Whether no point of b lies outside a, edges included. a may be a BoundingBox, whose sides are compared directly, or a Circle, holding the points within its radius of its centre.
geo.within(a: T, b: U, distance: Length?) -> Bool: geo.contains(b, a); or, with distance:, whether two points are at most that far apart, as geo.distance measures them.

It also takes text.format, json.read, json.write and ==. How every standard type behaves says how they work.

Markdown for agents: /docs/types/type-circle.md.Built from Jadpo main at aee2e8f.