Source code for pina.loss.linear_weighting
"""Module for the LinearWeighting class."""
from ..loss import WeightingInterface
from ..utils import check_consistency, check_positive_integer
[docs]
class LinearWeighting(WeightingInterface):
"""
A weighting scheme that linearly scales weights from initial values to final
values over a specified number of epochs.
"""
def __init__(self, initial_weights, final_weights, target_epoch):
"""
:param dict initial_weights: The weights to be assigned to each loss
term at the beginning of training. The keys are the conditions and
the values are the corresponding weights. If a condition is not
present in the dictionary, the default value (1) is used.
:param dict final_weights: The weights to be assigned to each loss term
once the target epoch is reached. The keys are the conditions and
the values are the corresponding weights. If a condition is not
present in the dictionary, the default value (1) is used.
:param int target_epoch: The epoch at which the weights reach their
final values.
:raises ValueError: If the keys of the two dictionaries are not
consistent.
"""
super().__init__(update_every_n_epochs=1, aggregator="sum")
# Check consistency
check_consistency([initial_weights, final_weights], dict)
check_positive_integer(value=target_epoch, strict=True)
# Check that the keys of the two dictionaries are the same
if initial_weights.keys() != final_weights.keys():
raise ValueError(
"The keys of the initial_weights and final_weights "
"dictionaries must be the same."
)
# Initialization
self.initial_weights = initial_weights
self.final_weights = final_weights
self.target_epoch = target_epoch
[docs]
def weights_update(self, losses):
"""
Update the weighting scheme based on the given losses.
:param dict losses: The dictionary of losses.
:return: The updated weights.
:rtype: dict
"""
return {
condition: self.last_saved_weights().get(
condition, self.initial_weights.get(condition, 1)
)
+ (
self.final_weights.get(condition, 1)
- self.initial_weights.get(condition, 1)
)
/ (self.target_epoch)
for condition in losses.keys()
}