add check for valid dimension name before creating new variable (#360)

* fix: unsupported dimension names (#359)

Add function to ensure that added variables do not use unvalid dimension names.

* Update linopy/model.py

More condensed check of dim_names

Co-authored-by: Lukas Trippe <lkstrp@pm.me>

* Update linopy/model.py

remove unnecessary else block

Co-authored-by: Lukas Trippe <lkstrp@pm.me>

* Update linopy/model.py

make check_valid_dim_names private

Co-authored-by: Lukas Trippe <lkstrp@pm.me>

* Update linopy/model.py

make check_valid_dim_names private

Co-authored-by: Lukas Trippe <lkstrp@pm.me>

---------

Co-authored-by: Lukas Trippe <lkstrp@pm.me>

linopy/model.py

@@ -367,6 +367,32 @@ def check_force_dim_names(self, ds: DataArray | Dataset) -> None:
         else:
             return
 
+    def _check_valid_dim_names(self, ds: DataArray | Dataset) -> None:
+        """
+        Ensure that the added data does not lead to a naming conflict.
+
+        Parameters
+        ----------
+        model : linopy.Model
+        ds : xr.DataArray/Variable/LinearExpression
+            Data that should be added to the model.
+
+        Raises
+        ------
+        ValueError
+            If broadcasted data leads to unsupported dimension names.
+
+        Returns
+        -------
+        None.
+        """
+        unsupported_dim_names = ["labels", "coeffs", "vars", "sign", "rhs"]
+        if any(dim in unsupported_dim_names for dim in ds.dims):
+            raise ValueError(
+                "Added data contains unsupported dimension names. "
+                "Dimensions cannot be named 'labels', 'coeffs', 'vars', 'sign' or 'rhs'."
+            )
+
     def add_variables(
         self,
         lower: Any = -inf,
@@ -474,6 +500,7 @@ def add_variables(
         )
         (data,) = xr.broadcast(data)
         self.check_force_dim_names(data)
+        self._check_valid_dim_names(data)
 
         if mask is not None:
             mask = as_dataarray(mask, coords=data.coords, dims=data.dims).astype(bool)

test/test_variable_assignment.py

@@ -131,6 +131,15 @@ def test_variable_assignment_without_coords_and_dims_names():
     assert x.dims == ("i", "j")
 
 
+def test_variable_assignment_without_coords_and_invalid_dims_names():
+    # setting bounds without explicit coords
+    m = Model()
+    lower = np.zeros((10, 10))
+    upper = np.ones((10, 10))
+    with pytest.raises(ValueError):
+        m.add_variables(lower, upper, name="x", dims=["sign", "j"])
+
+
 def test_variable_assignment_without_coords_in_bounds():
     # setting bounds without explicit coords
     m = Model()
@@ -141,6 +150,15 @@ def test_variable_assignment_without_coords_in_bounds():
     assert x.dims == ("i", "j")
 
 
+def test_variable_assignment_without_coords_in_bounds_invalid_dims_names():
+    # setting bounds without explicit coords
+    m = Model()
+    lower = xr.DataArray(np.zeros((10, 10)), dims=["i", "sign"])
+    upper = xr.DataArray(np.ones((10, 10)), dims=["i", "sign"])
+    with pytest.raises(ValueError):
+        m.add_variables(lower, upper, name="x")
+
+
 def test_variable_assignment_without_coords_pandas_types():
     # setting bounds without explicit coords
     m = Model()