UnitSphere

class gpjax.xarray.UnitSphere(lat='lat', lon='lon', name='sphere')

Bases: InputTransform

Map latitude and longitude in degrees to a point on the unit sphere.

The two columns are replaced, at the position of lat, by {name}_x = cos(lat) cos(lon), {name}_y = cos(lat) sin(lon) and {name}_z = sin(lat). A stationary kernel on these columns uses the chord distance through the sphere, which is valid on the whole globe: it has no seam at the antimeridian, no singularity at the poles, and it does not stretch distances at high latitudes. A lengthscale is then in Earth radii (one radius is about 6371 km).

Parameters:

• lat (str)

• lon (str)

• name (str)

lat

Name of the latitude column, in degrees north.

Type:

str

lon

Name of the longitude column, in degrees east.

Type:

str

name

Prefix of the three new columns.

Type:

str

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