fem.properties.quantize_to_materials

fem.properties.quantize_to_materials(values, references, *, keys)

Snap a per-element property field onto a finite set of named materials.

Solvers that describe materials by name rather than by per-element arrays — CalculiX being the case in hand, with its *MATERIAL / *ELSET / *SOLID SECTION triple — cannot represent a continuously blended interface at all. This projects each element onto its nearest reference material in log-property space (properties span many decades, so a relative metric is the only sane one), which is exact wherever the blend is sharp and approximate exactly in the transition band.

Parameters

Name	Type	Description	Default
values	dict[str, Any]	Per-element property arrays keyed by property name, `(C,)` each (concrete; quantization is not differentiable).	required
references	Sequence[Any]	Reference :class:`~cadjoint.render.material.Material` objects to snap to.	required
keys	Sequence[str]	Which properties participate in the distance.	required

Returns

Name	Type	Description
	tuple[np.ndarray, np.ndarray]	`(assignment, error)` — `assignment` is a `(C,)` int array of indices into `references`, and `error` is the `(C,)` maximum relative property error the snap introduced (0 where an element landed exactly on a reference material).

Raises

Name	Type	Description
	ValueError	If `references` is empty or a reference does not specify one of `keys`.