Extent Definition

Extent

class osdatahub.extent.Extent(polygon: shapely.geometry.polygon.Polygon, crs: str)

Bases: object

Extent is a dataclass that has two main uses:

  • It is a standardised way to store polygon extents that will interface with all of the osdatahub APIs.

  • It has multiple constructors that allow the user to create custom Extents without needing to write out polygon coordinates.

property bbox: osdatahub.bbox.BBox
crs: str
classmethod from_bbox(bbox: Union[Collection[float], osdatahub.bbox.BBox], crs: str) → osdatahub.extent.Extent

Creates a rectangular extent, given a bounding box.

Parameters

  • bbox (Union[Collection[float], BBox]) – A bounding box, passed in as either a BBox object or a collection of the form (west, south, east, north).

  • crs (str) – The CRS corresponding to the bouding box, must be either ‘’EPSG:4326’, EPSG:27700’ or ‘EPSG:3857’.

Raises

TypeError – If bbox is not a tuple or BBox object.

Returns

A rectangular extent that matches the specified bounding box.

Return type

Extent

classmethod from_ons_code(ons_code: str) → osdatahub.extent.Extent

Creates an extent of an existing ONS boundary. Note that the output will be in the “EPSG:4326” coordinate system. A full list of available ONS geographies can be found here: http://statistics.data.gov.uk/atlas/resource?uri=http://statistics.data.gov.uk/id/statistical-geography/K02000001

Parameters

ons_code (str) – The code for the desired geography

Raises

ValueError – If the ONS geography is not a Polygon.

Returns

An extent of the ONS geography.

Return type

Extent

classmethod from_radius(centre: Iterable, radius: float, crs: str) → osdatahub.extent.Extent

Creates a circular extent, given a centre point and a radius.

Parameters

  • centre (Iterable) – Either a coordinate tuple in the form (x, y) or a shapely Point.

  • radius (float) – The radius of the circle in metres

  • crs (str) – The CRS corresponding to the point coordinate, must be either ‘EPSG:27700’ or ‘EPSG:3857’.

Raises

TypeError – If centre is not a tuple or shapely Point.

Returns

A rectangular extent that matches the specified bounding box.

Return type

Extent

is_within(bbox: Union[Collection[float], osdatahub.bbox.BBox]) → bool

Checks whether a bounding box is within the Extent object

Parameters

bbox (Union[Collection[float], BBox]) – A bounding box, passed in as either a BBox object or a collection of the form (west, south, east, north).

Returns

True if the bounding box is within the Extent object, False if not

Return type

bool

polygon: shapely.geometry.polygon.Polygon
set_crs(crs: str) → osdatahub.extent.Extent

Changes the coordinate reference system of the Extent object to the value specified

Parameters

crs (str) – The CRS to change to, must be either ‘’EPSG:4326’, EPSG:27700’ or ‘EPSG:3857’.

Returns

A rectangular extent with an updated CRS

Return type

Extent

to_json()

Converts the extent object into a json

Returns

A json containing the coordinates of the Extent

Return type

dict

property xml_coords: str