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Weights in alpha for FocalLoss #8601
Description
Currently, MONAI’s FocalLoss accepts alpha as a single scalar to balance background vs. foreground. This prevents specifying different weights for each class in multi-class segmentation, which is problematic for highly imbalanced datasets.
I would like FocalLoss to support alpha as a tensor or list of floats, allowing a separate weight for each class (e.g., [0.1, 0.3, 0.6] for a 3-class problem). Allowing per-class alpha directly would provide more precise control and better alignment with the original focal loss formulation.
Activity
aymuos15 commentedon Nov 3, 2025
I would be interested in approaching this if it's open to implementation
avithal commentedon Dec 16, 2025
if none takes it i can do it
Weights in alpha for FocalLoss (Project-MONAI#8665)
Weights in alpha for FocalLoss (Project-MONAI#8665)
Weights in alpha for FocalLoss (Project-MONAI#8665)
Weights in alpha for FocalLoss (Project-MONAI#8665)