Tied

class pmrf.models.composite.wrapped.Tied(model: ~pmrf.models.base.Model, target: ~typing.Callable[[~typing.Any], ~typing.Any], source: ~typing.Callable[[~typing.Any], ~typing.Any], tie_fn: ~typing.Callable[[~typing.Any], ~typing.Any] = <function Tied.<lambda>>)

Bases: Model

A composite model that links or ‘ties’ fields within a sub-model together.

This model wraps a base model and allows enforcing a functional relationship between a target and a source node within the model. For example, this can be used to enforce two parameters to be equal.

Upon initialization, the target is replaced with a placeholder, hiding it from optimizers. When the model is evaluated (via build), the relationship is unwrapped and the target is resolved.

Variables:

tied_wrapper (parax.Tie) – The wrapped parax Tie object handling the parameter linking.

Examples

>>> import pmrf as prf
>>> from pmrf.models import Resistor, Capacitor
>>>
>>> rc = Resistor(R=50.0) ** Capacitor(C=1.0e-12)
>>>
>>> # Tie the resistor's R to always be 50e12 times the capacitor's C
>>> tied_rc = Tied(
...     model=rc,
...     target=lambda m: m.models[0].R,
...     source=lambda m: m.models[1].C,
...     tie_fn=lambda c: c * 50e12
... )
>>>
>>> # The optimizer will now only see the Capacitor's C parameter.
>>> # When evaluated, R will automatically track C.

Initialize the Tied model.

Parameters:

  • model (Model) – The base RF model whose parameters should be tied.

  • target (callable) – A callable (lens) extracting the parameter to be overwritten (e.g., lambda m: m.resistor.R).

  • source (callable) – A callable (lens) extracting the parameter to draw the value from (e.g., lambda m: m.capacitor.C).

  • tie_fn (callable, optional) – An optional transformation function applied to the source before injecting it into the target. Defaults to the identity function (lambda x: x).

property model: Model

Returns the underlying model that has tied placeholders.

wrapped: Tie