From adff16230ad4d4c4e32149eb0e72eea706b40d2e Mon Sep 17 00:00:00 2001
From: ytl0623 <david89062388@gmail.com>
Date: Fri, 16 Jan 2026 11:03:23 +0800
Subject: [PATCH] Adjust execution order of activation and masking in
 MaskedDiceLoss

Signed-off-by: ytl0623 <david89062388@gmail.com>
---
 monai/losses/dice.py                  | 30 ++++++++++++++++++++++++++-
 tests/losses/test_masked_dice_loss.py |  6 +++---
 2 files changed, 32 insertions(+), 4 deletions(-)

diff --git a/monai/losses/dice.py b/monai/losses/dice.py
index 948749606b..3d810bc1fe 100644
--- a/monai/losses/dice.py
+++ b/monai/losses/dice.py
@@ -244,7 +244,22 @@ def __init__(self, *args: Any, **kwargs: Any) -> None:
         Args follow :py:class:`monai.losses.DiceLoss`.
         """
         super().__init__(*args, **kwargs)
-        self.spatial_weighted = MaskedLoss(loss=super().forward)
+        self.dice = DiceLoss(
+            include_background=self.include_background,
+            to_onehot_y=self.to_onehot_y,
+            sigmoid=False,
+            softmax=False,
+            other_act=None,
+            squared_pred=self.squared_pred,
+            jaccard=self.jaccard,
+            reduction=self.reduction,
+            smooth_nr=self.smooth_nr,
+            smooth_dr=self.smooth_dr,
+            batch=self.batch,
+            weight=self.class_weight,
+            soft_label=self.soft_label,
+        )
+        self.spatial_weighted = MaskedLoss(loss=self.dice.forward)
 
     def forward(self, input: torch.Tensor, target: torch.Tensor, mask: torch.Tensor | None = None) -> torch.Tensor:
         """
@@ -253,6 +268,19 @@ def forward(self, input: torch.Tensor, target: torch.Tensor, mask: torch.Tensor
             target: the shape should be BNH[WD].
             mask: the shape should B1H[WD] or 11H[WD].
         """
+
+        if self.sigmoid:
+            input = torch.sigmoid(input)
+
+        n_pred_ch = input.shape[1]
+        if self.softmax:
+            if n_pred_ch == 1:
+                warnings.warn("single channel prediction, `softmax=True` ignored.")
+            else:
+                input = torch.softmax(input, 1)
+
+        if self.other_act is not None:
+            input = self.other_act(input)
         return self.spatial_weighted(input=input, target=target, mask=mask)  # type: ignore[no-any-return]
 
 
diff --git a/tests/losses/test_masked_dice_loss.py b/tests/losses/test_masked_dice_loss.py
index c971723615..ea08254ee5 100644
--- a/tests/losses/test_masked_dice_loss.py
+++ b/tests/losses/test_masked_dice_loss.py
@@ -27,7 +27,7 @@
             "target": torch.tensor([[[[1.0, 0.0], [1.0, 1.0]]]]),
             "mask": torch.tensor([[[[0.0, 0.0], [1.0, 1.0]]]]),
         },
-        0.500,
+        0.333333,
     ],
     [  # shape: (2, 1, 2, 2), (2, 1, 2, 2)
         {"include_background": True, "sigmoid": True, "smooth_nr": 1e-4, "smooth_dr": 1e-4},
@@ -36,7 +36,7 @@
             "target": torch.tensor([[[[1.0, 1.0], [1.0, 1.0]]], [[[1.0, 0.0], [1.0, 0.0]]]]),
             "mask": torch.tensor([[[[1.0, 1.0], [1.0, 1.0]]], [[[1.0, 1.0], [0.0, 0.0]]]]),
         },
-        0.422969,
+        0.301128,
     ],
     [  # shape: (2, 2, 3), (2, 1, 3)
         {"include_background": False, "to_onehot_y": True, "smooth_nr": 0, "smooth_dr": 0},
@@ -54,7 +54,7 @@
             "target": torch.tensor([[[1.0, 0.0, 0.0]], [[1.0, 1.0, 0.0]]]),
             "mask": torch.tensor([[[1.0, 1.0, 0.0]]]),
         },
-        0.47033,
+        0.579184,
     ],
     [  # shape: (2, 2, 3), (2, 1, 3)
         {