feat(aggregation): Add getters and setters to UPGrad parameters (#658)

* Add reg_eps getter and setter to UPGrad and UPGradWeighting
* Add norm_eps getter and setter to UPGrad and UPGradWeighting
* Add pref_vector getter and setter to UPGrad and UPGradWeighting
* Add tests for setters
* Add changelog entry

Author: mattbuot

CHANGELOG.md

@@ -8,6 +8,12 @@ changelog does not include internal changes that do not affect the user.
 
 ## [Unreleased]
 
+### Added
+
+- Added `pref_vector`, `norm_eps`, and `reg_eps` getters and setters to `UPGrad` and
+  `UPGradWeighting`. The setters for `norm_eps` and `reg_eps` validate that the assigned value is
+  non-negative.
+
 ## [0.10.0] - 2026-04-16
 
 ### Added

src/torchjd/aggregation/_upgrad.py

@@ -34,8 +34,7 @@ def __init__(
         solver: SUPPORTED_SOLVER = "quadprog",
     ) -> None:
         super().__init__()
-        self._pref_vector = pref_vector
-        self.weighting = pref_vector_to_weighting(pref_vector, default=MeanWeighting())
+        self.pref_vector = pref_vector
         self.norm_eps = norm_eps
         self.reg_eps = reg_eps
         self.solver: SUPPORTED_SOLVER = solver
@@ -46,6 +45,39 @@ def forward(self, gramian: PSDMatrix, /) -> Tensor:
         W = project_weights(U, G, self.solver)
         return torch.sum(W, dim=0)
 
+    @property
+    def pref_vector(self) -> Tensor | None:
+        return self._pref_vector
+
+    @pref_vector.setter
+    def pref_vector(self, value: Tensor | None) -> None:
+        self.weighting = pref_vector_to_weighting(value, default=MeanWeighting())
+        self._pref_vector = value
+
+    @property
+    def norm_eps(self) -> float:
+        return self._norm_eps
+
+    @norm_eps.setter
+    def norm_eps(self, value: float) -> None:
+
+        if value < 0:
+            raise ValueError(f"norm_eps must be non-negative, but got {value}.")
+
+        self._norm_eps = value
+
+    @property
+    def reg_eps(self) -> float:
+        return self._reg_eps
+
+    @reg_eps.setter
+    def reg_eps(self, value: float) -> None:
+
+        if value < 0:
+            raise ValueError(f"reg_eps must be non-negative, but got {value}.")
+
+        self._reg_eps = value
+
 
 class UPGrad(GramianWeightedAggregator):
     r"""
@@ -73,9 +105,6 @@ def __init__(
         reg_eps: float = 0.0001,
         solver: SUPPORTED_SOLVER = "quadprog",
     ) -> None:
-        self._pref_vector = pref_vector
-        self._norm_eps = norm_eps
-        self._reg_eps = reg_eps
         self._solver: SUPPORTED_SOLVER = solver
 
         super().__init__(
@@ -85,11 +114,35 @@ def __init__(
         # This prevents considering the computed weights as constant w.r.t. the matrix.
         self.register_full_backward_pre_hook(raise_non_differentiable_error)
 
+    @property
+    def pref_vector(self) -> Tensor | None:
+        return self.gramian_weighting.pref_vector
+
+    @pref_vector.setter
+    def pref_vector(self, value: Tensor | None) -> None:
+        self.gramian_weighting.pref_vector = value
+
+    @property
+    def norm_eps(self) -> float:
+        return self.gramian_weighting.norm_eps
+
+    @norm_eps.setter
+    def norm_eps(self, value: float) -> None:
+        self.gramian_weighting.norm_eps = value
+
+    @property
+    def reg_eps(self) -> float:
+        return self.gramian_weighting.reg_eps
+
+    @reg_eps.setter
+    def reg_eps(self, value: float) -> None:
+        self.gramian_weighting.reg_eps = value
+
     def __repr__(self) -> str:
         return (
-            f"{self.__class__.__name__}(pref_vector={repr(self._pref_vector)}, norm_eps="
-            f"{self._norm_eps}, reg_eps={self._reg_eps}, solver={repr(self._solver)})"
+            f"{self.__class__.__name__}(pref_vector={repr(self.pref_vector)}, norm_eps="
+            f"{self.norm_eps}, reg_eps={self.reg_eps}, solver={repr(self._solver)})"
         )
 
     def __str__(self) -> str:
-        return f"UPGrad{pref_vector_to_str_suffix(self._pref_vector)}"
+        return f"UPGrad{pref_vector_to_str_suffix(self.pref_vector)}"

tests/unit/aggregation/test_upgrad.py

@@ -1,9 +1,10 @@
 import torch
-from pytest import mark
+from pytest import mark, raises
 from torch import Tensor
 from utils.tensors import ones_
 
-from torchjd.aggregation import UPGrad
+from torchjd.aggregation import ConstantWeighting, UPGrad
+from torchjd.aggregation._upgrad import UPGradWeighting
 
 from ._asserts import (
     assert_expected_structure,
@@ -67,3 +68,48 @@ def test_representations() -> None:
         "solver='quadprog')"
     )
     assert str(A) == "UPGrad([1., 2., 3.])"
+
+
+def test_pref_vector_setter_updates_value() -> None:
+    A = UPGrad()
+    new_pref = torch.tensor([1.0, 2.0, 3.0])
+    A.pref_vector = new_pref
+    assert A.pref_vector is new_pref
+    assert isinstance(A.gramian_weighting.weighting, ConstantWeighting)
+    assert A.gramian_weighting.weighting.weights is new_pref
+
+
+def test_norm_eps_setter_updates_value() -> None:
+    A = UPGrad()
+    A.norm_eps = 0.25
+    assert A.norm_eps == 0.25
+
+
+def test_reg_eps_setter_updates_value() -> None:
+    A = UPGrad()
+    A.reg_eps = 0.25
+    assert A.reg_eps == 0.25
+
+
+def test_norm_eps_setter_rejects_negative() -> None:
+    A = UPGrad()
+    with raises(ValueError, match="norm_eps"):
+        A.norm_eps = -1e-9
+
+
+def test_reg_eps_setter_rejects_negative() -> None:
+    A = UPGrad()
+    with raises(ValueError, match="reg_eps"):
+        A.reg_eps = -1e-9
+
+
+def test_weighting_norm_eps_setter_rejects_negative() -> None:
+    W = UPGradWeighting()
+    with raises(ValueError, match="norm_eps"):
+        W.norm_eps = -1e-9
+
+
+def test_weighting_reg_eps_setter_rejects_negative() -> None:
+    W = UPGradWeighting()
+    with raises(ValueError, match="reg_eps"):
+        W.reg_eps = -1e-9