Functions

topojson.read `builtin`

read(file: str) -> TopoJSON

Read into a TopoJSON from a JSON file.

Parameters:

Name	Type	Description	Default
`file`	`str`	Path to a file	required

Returns:

Type	Description
`TopoJSON`	TopoJSON object

Raises:

Type	Description
`OsError`	Unable to find, open or read the file.
`RuntimeError`	Unable to deserialize the file.

topojson.feature `builtin`

feature(topology: TopoJSON, o: Geometry) -> GeoJSON

Returns the GeoJSON Feature or FeatureCollection for the specified object in the given topology. If the object is a Geometry_GeometryCollection, a GeoJSON_FeatureCollection is returned, and each geometry in the collection is mapped to a Feature. Otherwise, a Feature is returned. The returned feature is a shallow copy of the source object: they may share identifiers, bounding boxes, properties and coordinates.

Parameters:

Name	Type	Description	Default
`topology`	`TopoJSON`	Topology object	required
`o`	`Geometry`	Geometry	required

Returns:

Type	Description
`GeoJSON`	GeoJSON Feature or FeatureCollection

Examples:

A point is mapped to a feature with a geometry object of type "Point".
Likewise for line strings, polygons, and other simple geometries.
A null geometry object (of type null in TopoJSON) is mapped to a feature with a null geometry object.
A geometry collection of points is mapped to a feature collection of features, each with a point geometry.
A geometry collection of geometry collections is mapped to a feature collection of features, each with a geometry collection.

topojson.merge `builtin`

merge(topology: TopoJSON, objects) -> FeatureGeometryType_MultiLineString

Returns the GeoJSON MultiPolygon geometry object representing the union for the specified array of Polygon and MultiPolygon objects in the given topology. Interior borders shared by adjacent polygons are removed. See Merging States for an example. The returned geometry is a shallow copy of the source object: they may share coordinates.

Parameters:

Name	Type	Description	Default
`topology`	`TopoJSON`	Topology object	required
`o`	`Geometry`	Geometry	required

Returns:

Type	Description
`FeatureGeometryType_MultiLineString`	GeoJSON MultiPolygon geometry object

Raises:

Type	Description
`KeyError`	When `key` is not found in `objects`
`TypeError`	Selected object is not a `Geometry_GeometryCollection`.

topojson.mesh `builtin`

mesh(topology: TopoJSON, object: Optional[Geometry], filter: Optional[Callable[[Geometry, Geometry], bool]]) -> FeatureGeometryType_MultiLineString

Returns the GeoJSON MultiLineString geometry object representing the mesh for the specified object in the given topology. This is useful for rendering strokes in complicated objects efficiently, as edges that are shared by multiple features are only stroked once. If object is not specified, a mesh of the entire topology is returned. The returned geometry is a shallow copy of the source object: they may share coordinates.

Parameters:

Name	Type	Description	Default
`topology`	`TopoJSON`	TopoJSON object containing the object to mesh	required
`object`	`Optional[Geometry]`	Specfied geometry to mesh	`None`
`filter`	`Optional[Callable[[Geometry, Geometry], bool]]`	The filter function is called once for each candidate arc and takes two arguments, a and b, two geometry objects that share that arc. Each arc is only included in the resulting mesh if the filter function returns true. For typical map topologies the geometries a and b are adjacent polygons and the candidate arc is their boundary. If an arc is only used by a single geometry then a and b are identical.	`None`

Returns:

Type	Description
`FeatureGeometryType_MultiLineString`	GeoJSON MultiLineString geometry object

Warnings

Currently, filter argument does not change the result because it is avoided due to performance issues.

Raises:

Type	Description
`KeyError`	When `key` is not found in `objects`

topojson.neighbors `builtin`

neighbors(objects: list[Geometry]) -> list[list[int]]

Returns an array representing the set of neighboring objects for each object in the specified objects array. The returned array has the same number of elements as the input array; each element i in the returned array is the array of indexes for neighbors of object i in the input array. For example, if the specified objects array contains the features foo and bar, and these features are neighbors, the returned array will be [[1], [0]], indicating that foo is a neighbor of bar and vice versa. Each array of neighbor indexes for each object is guaranteed to be sorted in ascending order.

Parameters:

Name	Type	Description	Default
`objects`	`list[Geometry]`	List of neighboring objects	required

Returns:

Type	Description
`list[list[int]]`	Neighboring objects

Raises:

Type	Description
`KeyError`	When `key` is not found in `objects`

topojson.bbox `builtin`

bbox(topology: TopoJSON) -> list[float]

Returns the computed bounding box of the specified topology \([x_0, y_0, x_1, y_1]\) where \(x_0\) is the minimum x-value, \(y_0\) is the minimum y-value, x_1 is the maximum x-value, and \(y_1\) is the maximum y-value. If the topology has no points and no arcs, the returned bounding box is \([\infty, \infty, -\infty, -\infty]\).

(This method ignores the existing topology.bbox, if any.)

Parameters:

Name	Type	Description	Default
`topology`	`TopoJSON`	TopoJSON object	required

Returns:

Type	Description
`list[float]`	Computed bounding box

topojson.quantize `builtin`

quantize(topology: TopoJSON, transform: float) -> TopoJSON

Returns a shallow copy of the specified topology with quantized and delta-encoded arcs according to the specified transform object. If the topology is already quantized, an error is thrown. See also topoquantize.

The corresponding transform object is first computed using the bounding box of the topology. The quantization number transform must be a positive integer greater than one which determines the maximum number of expressible values per dimension in the resulting quantized coordinates; typically, a power of ten is chosen such as 1e4, 1e5 or 1e6. If the topology does not already have a topology.bbox, one is computed using topojson.bbox.

Parameters:

Name	Type	Description	Default
`topology`	`TopoJSON`	TopoJSON object to quantize	required
`transform`	`float`	The quantization number `transform`.	required

Returns:

Type	Description
`TopoJSON`	Shallow copy with quantized and delta-encoded arcs.

Raises:

Type	Description
`RuntimeError`	If topology is already quantized or transform is smaller than 2.

Functions

topojson.read `builtin`

`file`

topojson.feature `builtin`

`topology`

`o`

topojson.merge `builtin`

`topology`

`o`

topojson.mesh `builtin`

`topology`

`object`

`filter`

topojson.neighbors `builtin`

`objects`

topojson.bbox `builtin`

`topology`

topojson.quantize `builtin`

`topology`

`transform`

Functions

topojson.read builtin

file

topojson.feature builtin

topology

o

topojson.merge builtin

topology

o

topojson.mesh builtin

topology

object

filter

topojson.neighbors builtin

objects

topojson.bbox builtin

topology

topojson.quantize builtin

topology

transform

topojson.read `builtin`

`file`

topojson.feature `builtin`

`topology`

`o`

topojson.merge `builtin`

`topology`

`o`

topojson.mesh `builtin`

`topology`

`object`

`filter`

topojson.neighbors `builtin`

`objects`

topojson.bbox `builtin`

`topology`

topojson.quantize `builtin`

`topology`

`transform`