"""Define a simple optimization objective.
It is a simple difference over a given quantity between the reference linac and
the linac under tuning.
"""
import logging
from lightwin.beam_calculation.simulation_output.simulation_output import (
SimulationOutput,
)
from lightwin.core.elements.element import Element
from lightwin.optimisation.objective.objective import Objective
[docs]
class MinimizeDifferenceWithRef(Objective):
"""A simple difference at a given point between ref and fix."""
[docs]
def __init__(
self,
name: str,
weight: float,
get_key: str,
get_kwargs: dict[str, Element | str | bool],
reference: SimulationOutput,
descriptor: str | None = None,
) -> None:
"""
Set complementary :meth:`.SimulationOutput.get` flags, reference value.
Parameters
----------
get_key : str
Name of the quantity to get, which must be an attribute of
:class:`.SimulationOutput`.
get_kwargs : dict[str, Element | str | bool]
Keyword arguments for the :meth:`.SimulationOutput.get` method. We
do not check its validity, but in general you will want to define
the keys ``elt`` and ``pos``. If objective concerns a phase, you
may want to precise the ``to_deg`` key. You also should explicit
the ``to_numpy`` key.
reference : SimulationOutput
The reference simulation output from which the ideal value will be
taken.
"""
self.get_key = get_key
self.get_kwargs = get_kwargs
super().__init__(
name,
weight,
descriptor=descriptor,
ideal_value=self._value_getter(reference),
)
self._check_ideal_value()
[docs]
def base_str(self) -> str:
"""Tell nature and position of objective."""
message = f"{self.get_key:>23}"
elt = str(self.get_kwargs.get("elt", "NA"))
message += f" @elt {elt:>5}"
pos = str(self.get_kwargs.get("pos", "NA"))
message += f" ({pos:>3}) | {self.weight:>5} | "
return message
[docs]
def __str__(self) -> str:
"""Give objective information value."""
message = self.base_str()
if isinstance(self.ideal_value, float):
message += f"{self.ideal_value:+.14e}"
return message
if isinstance(self.ideal_value, tuple):
message += (
f"{self.ideal_value[0]:+.2e} ~ {self.ideal_value[1]:+.2e}"
)
return message
if self.ideal_value is None:
message += f"{'None': ^21}"
return message
return message
[docs]
def _value_getter(self, simulation_output: SimulationOutput) -> float:
"""Get desired value using :meth:`.SimulationOutput.get` method."""
return simulation_output.get(self.get_key, **self.get_kwargs)
[docs]
def _check_ideal_value(self) -> None:
"""Assert the the reference value is a float."""
if not isinstance(self.ideal_value, float):
logging.warning(
f"Tried to get {self.get_key} with {self.get_kwargs}, which "
f"returned {self.ideal_value} instead of a float."
)
[docs]
def evaluate(self, simulation_output: SimulationOutput) -> float:
value = self._value_getter(simulation_output)
return self._compute_residues(value)
[docs]
def _compute_residues(self, value: float) -> float:
"""Compute the residues."""
return self.weight * (value - self.ideal_value)