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from .base import *
from typing import Literal
from pydantic import BaseModel, ConfigDict
class MSELossParams(BaseModel):
"""
Class for MSE loss parameters, compatible with `nn.MSELoss`.
"""
model_config = ConfigDict(frozen=True)
reduction: Literal["none", "mean", "sum"] = "mean"
def asdict(self) -> Dict[str, Any]:
"""
Returns a dictionary of valid parameters for `nn.MSELoss`.
Returns:
Dict[str, Any]: Dictionary of parameters for `nn.MSELoss`.
"""
loss_kwargs = self.model_dump()
return {k: v for k, v in loss_kwargs.items() if v is not None} # Remove None values
class MSELoss(BaseLoss):
"""
Custom loss function wrapper for `nn.MSELoss` with tracking of loss metrics.
"""
def __init__(self, mse_params: Optional[MSELossParams] = None):
"""
Initializes the loss function with optional MSELoss parameters.
Args:
mse_params (Optional[MSELossParams]): Parameters for `nn.MSELoss` (default: None).
"""
super().__init__()
_mse_params = mse_params.asdict() if mse_params is not None else {}
# Initialize MSE loss with user-provided parameters or PyTorch defaults
self.mse_loss = nn.MSELoss(**_mse_params)
# Using CumulativeAverage from MONAI to track loss metrics
self.loss_mse_metric = CumulativeAverage()
def forward(self, outputs: torch.Tensor, target: torch.Tensor) -> torch.Tensor:
"""
Computes the loss between true values and predictions.
Args:
outputs (torch.Tensor): Model predictions of shape (batch_size, channels, H, W).
target (torch.Tensor): Ground truth labels of shape (batch_size, channels, H, W).
Returns:
torch.Tensor: The total loss value.
"""
# Ensure target is on the same device as outputs
assert (
target.device == outputs.device
), (
"Target tensor must be moved to the same device as outputs "
"before calling forward()."
)
loss = self.mse_loss(outputs, target)
self.loss_mse_metric.append(loss.item())
return loss
def get_loss_metrics(self) -> Dict[str, float]:
"""
Retrieves the tracked loss metrics.
Returns:
Dict[str, float]: A dictionary containing the average MSE loss.
"""
return {
"loss": round(self.loss_mse_metric.aggregate().item(), 4),
}
def reset_metrics(self):
"""Resets the stored loss metrics."""
self.loss_mse_metric.reset()