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"""
This module is for building datums to be used when
building a CRS.
"""
from typing import Any
from pyproj._crs import Datum, Ellipsoid, PrimeMeridian
class CustomDatum(Datum):
"""
.. versionadded:: 2.5.0
Class to build a datum based on an ellipsoid and prime meridian.
"""
def __new__(
cls,
name: str = "undefined",
ellipsoid: Any = "WGS 84",
prime_meridian: Any = "Greenwich",
):
"""
Parameters
----------
name: str, default="undefined"
Name of the datum.
ellipsoid: Any, default="WGS 84"
Anything accepted by :meth:`pyproj.crs.Ellipsoid.from_user_input`
or a :class:`pyproj.crs.datum.CustomEllipsoid`.
prime_meridian: Any, default="Greenwich"
Anything accepted by :meth:`pyproj.crs.PrimeMeridian.from_user_input`.
"""
datum_json = {
"$schema": "https://proj.org/schemas/v0.2/projjson.schema.json",
"type": "GeodeticReferenceFrame",
"name": name,
"ellipsoid": Ellipsoid.from_user_input(ellipsoid).to_json_dict(),
"prime_meridian": PrimeMeridian.from_user_input(
prime_meridian
).to_json_dict(),
}
return cls.from_json_dict(datum_json)
class CustomEllipsoid(Ellipsoid):
"""
.. versionadded:: 2.5.0
Class to build a custom ellipsoid.
"""
def __new__(
cls,
name: str = "undefined",
semi_major_axis: float | None = None,
inverse_flattening: float | None = None,
semi_minor_axis: float | None = None,
radius: float | None = None,
):
"""
Parameters
----------
name: str, default="undefined"
Name of the ellipsoid.
semi_major_axis: float, optional
The semi major axis in meters. Required if missing radius.
inverse_flattening: float, optional
The inverse flattening in meters.
Required if missing semi_minor_axis and radius.
semi_minor_axis: float, optional
The semi minor axis in meters.
Required if missing inverse_flattening and radius.
radius: float, optional
The radius in meters. Can only be used alone.
Cannot be mixed with other parameters.
"""
ellipsoid_json: dict[str, float | str] = {
"$schema": "https://proj.org/schemas/v0.2/projjson.schema.json",
"type": "Ellipsoid",
"name": name,
}
if semi_major_axis is not None:
ellipsoid_json["semi_major_axis"] = semi_major_axis
if inverse_flattening is not None:
ellipsoid_json["inverse_flattening"] = inverse_flattening
if semi_minor_axis is not None:
ellipsoid_json["semi_minor_axis"] = semi_minor_axis
if radius is not None:
ellipsoid_json["radius"] = radius
return cls.from_json_dict(ellipsoid_json)
class CustomPrimeMeridian(PrimeMeridian):
"""
.. versionadded:: 2.5.0
Class to build a prime meridian based on a longitude.
"""
def __new__(cls, longitude: float, name: str = "undefined"):
"""
Parameters
----------
longitude: float
Longitude of prime meridian.
name: str, optional
Name of the prime meridian.
"""
datum_json = {
"$schema": "https://proj.org/schemas/v0.2/projjson.schema.json",
"type": "PrimeMeridian",
"name": name,
"longitude": longitude,
}
return cls.from_json_dict(datum_json)
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