Source:

• src/ometeotl_foundations/spatial/coordinate_system.py

Local role: Vocabulary for describing coordinate frames attached to geometries and spatial extents.

CoordinateKind

str, Enum. Nature of a coordinate system. Inherits from str so values serialise to their string form without a custom JSON encoder.

Values:

• CARTESIAN = "cartesian"
• GEOGRAPHIC = "geographic"
• GRID = "grid"
• CUSTOM = "custom"

CoordinateSystem

Frozen dataclass. Describes the coordinate frame used by a geometry or extent.

Fields:

• name: str — human-readable identifier (e.g. "wgs84")
• kind: CoordinateKind — broad category
• unit: str — native unit of measure ("meter", "degree", "cell")
• srid: Optional[int] = None — EPSG code for geographic/projected systems

Methods:

• to_dict() -> JsonMap — serialise to a plain dict; srid is omitted when None
• @classmethod from_dict(data) -> CoordinateSystem — reconstruct from dict; raises ValueError on missing or invalid kind

Predefined singletons

Example:

from ometeotl_foundations.spatial.coordinate_system import (
    CoordinateSystem, CoordinateKind, CARTESIAN_2D, WGS84
)

# Use a predefined singleton
cs = CARTESIAN_2D

# Reconstruct from dict (e.g. after JSON deserialisation)
cs2 = CoordinateSystem.from_dict(cs.to_dict())
assert cs2 == cs

# Custom CRS
custom = CoordinateSystem(
    name="local_grid",
    kind=CoordinateKind.CUSTOM,
    unit="meter",
)

See also:

• GeometricSpace
• SpatialExtent